[cfe] Use flatten(T) as future value type for pre-nnbd async functions

Change-Id: I38d537112e66c08bb06bc2493b3126b5f8f797b7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/239022
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -1294,6 +1294,10 @@ class BodyBuilder extends StackListenerImpl
           body);
       body = inferredFunctionBody.body;
       builder.function.futureValueType = inferredFunctionBody.futureValueType;
+      assert(
+          !(builder.function.asyncMarker == AsyncMarker.Async &&
+              builder.function.futureValueType == null),
+          "No future value type computed.");
       libraryBuilder.loader.transformPostInference(body, transformSetLiterals,
           transformCollections, libraryBuilder.library);
     }

pkg/front_end/lib/src/fasta/type_inference/closure_context.dart

@@ -65,8 +65,12 @@ abstract class ClosureContext {
               computeFutureValueType(inferrer.coreTypes, declaredReturnType);
         }
       } else {
-        returnContext = inferrer.wrapFutureOrType(
-            inferrer.typeSchemaEnvironment.flatten(returnContext));
+        DartType flattenedType =
+            inferrer.typeSchemaEnvironment.flatten(returnContext);
+        returnContext = inferrer.wrapFutureOrType(flattenedType);
+        if (!needToInferReturnType) {
+          futureValueType = flattenedType;
+        }
       }
       return new _AsyncClosureContext(returnContext, declaredReturnType,
           needToInferReturnType, futureValueType);
@@ -815,6 +819,8 @@ class _AsyncClosureContext implements ClosureContext {
     if (inferrer.isNonNullableByDefault) {
       futureValueType =
           computeFutureValueType(inferrer.coreTypes, inferredType);
+    } else {
+      futureValueType = inferrer.typeSchemaEnvironment.flatten(inferredType);
     }
     if (!inferrer.isTopLevel) {
       for (int i = 0; i < _returnStatements!.length; ++i) {

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

@@ -2105,10 +2105,7 @@ class TypeInferrerImpl implements TypeInferrer {
     result =
         closureContext!.handleImplicitReturn(this, body, result, fileOffset);
     DartType? futureValueType = closureContext!.futureValueType;
-    assert(
-        !(isNonNullableByDefault &&
-            asyncMarker == AsyncMarker.Async &&
-            futureValueType == null),
+    assert(!(asyncMarker == AsyncMarker.Async && futureValueType == null),
         "No future value type computed.");
     closureContext = null;
     this.helper = null;
@@ -2863,8 +2860,7 @@ class TypeInferrerImpl implements TypeInferrer {
         this, function.body!, bodyResult, fileOffset);
     function.futureValueType = closureContext.futureValueType;
     assert(
-        !(isNonNullableByDefault &&
-            function.asyncMarker == AsyncMarker.Async &&
+        !(function.asyncMarker == AsyncMarker.Async &&
             function.futureValueType == null),
         "No future value type computed.");
 

pkg/front_end/test/static_types/data/for_in.dart

@@ -48,7 +48,7 @@ forInIntToNum(List<int> list) {
   }
 }
 
-/*cfe:nnbd.member: asyncForInDynamicStream:futureValueType=dynamic*/
+/*member: asyncForInDynamicStream:futureValueType=dynamic*/
 asyncForInDynamicStream(dynamic stream) async {
   /*current: dynamic*/
   await for (var e in
@@ -59,7 +59,7 @@ asyncForInDynamicStream(dynamic stream) async {
   }
 }
 
-/*cfe:nnbd.member: asyncForInDynamic:futureValueType=dynamic*/
+/*member: asyncForInDynamic:futureValueType=dynamic*/
 asyncForInDynamic(Stream<dynamic> stream) async {
   /*current: dynamic*/
   await for (var e in
@@ -70,7 +70,7 @@ asyncForInDynamic(Stream<dynamic> stream) async {
   }
 }
 
-/*cfe:nnbd.member: asyncForInInt:futureValueType=dynamic*/
+/*member: asyncForInInt:futureValueType=dynamic*/
 asyncForInInt(Stream<int> stream) async {
   /*cfe.current: int*/
   /*cfe:nnbd.current: int!*/
@@ -84,7 +84,7 @@ asyncForInInt(Stream<int> stream) async {
   }
 }
 
-/*cfe:nnbd.member: asyncForInIntToNum:futureValueType=dynamic*/
+/*member: asyncForInIntToNum:futureValueType=dynamic*/
 asyncForInIntToNum(Stream<int> stream) async {
   /*cfe.current: int*/
   /*cfe:nnbd.current: int!*/
@@ -119,7 +119,7 @@ abstract class CustomStream implements Stream<num> {
   Iterator<int> get iterator;
 }
 
-/*cfe:nnbd.member: customStream:futureValueType=dynamic*/
+/*member: customStream:futureValueType=dynamic*/
 customStream(CustomStream stream) async {
   /*cfe.current: num*/
   /*cfe:nnbd.current: num!*/
@@ -158,7 +158,7 @@ abstract class StreamWithCustomIterator implements Stream<num> {
   CustomIterator get iterator;
 }
 
-/*cfe:nnbd.member: customStreamIterator:futureValueType=dynamic*/
+/*member: customStreamIterator:futureValueType=dynamic*/
 customStreamIterator(StreamWithCustomIterator stream) async {
   /*cfe.current: num*/
   /*cfe:nnbd.current: num!*/
@@ -183,7 +183,7 @@ void genericIterable<T extends Iterable<T>>(T x) {
   }
 }
 
-/*cfe:nnbd.member: genericStream:futureValueType=void*/
+/*member: genericStream:futureValueType=void*/
 void genericStream<T extends Stream<T>>(T x) async {
   /*cfe.current: T*/
   /*cfe:nnbd.current: T!*/

pkg/front_end/test/static_types/data/future_value_type.dart

@@ -9,50 +9,53 @@
 import 'dart:async';
 
 /*cfe:nnbd.member: declaredFutureInt:futureValueType=int!*/
+/*cfe.member: declaredFutureInt:futureValueType=int*/
 Future<int> declaredFutureInt() async {
   return
       /*cfe.int*/ /*cfe:nnbd.int!*/ 0;
 }
 
 /*cfe:nnbd.member: declaredFutureOrInt:futureValueType=int!*/
+/*cfe.member: declaredFutureOrInt:futureValueType=int*/
 FutureOr<int> declaredFutureOrInt() async {
   return
       /*cfe.int*/ /*cfe:nnbd.int!*/ 0;
 }
 
 /*cfe:nnbd.member: declaredObject:futureValueType=Object?*/
+/*cfe.member: declaredObject:futureValueType=Object*/
 Object declaredObject() async {
   return
       /*cfe.int*/ /*cfe:nnbd.int!*/ 0;
 }
 
-/*cfe:nnbd.member: omitted:futureValueType=dynamic*/
+/*member: omitted:futureValueType=dynamic*/
 omitted() async {}
 
-/*cfe:nnbd.member: method:futureValueType=dynamic*/
+/*member: method:futureValueType=dynamic*/
 method() async {
   /*cfe:nnbd.futureValueType=int!*/
-  Future<int> declaredLocalFutureInt() async {
+  /*cfe.futureValueType=int*/Future<int> declaredLocalFutureInt() async {
     return
         /*cfe.int*/ /*cfe:nnbd.int!*/ 0;
   }
 
   /*cfe:nnbd.futureValueType=int!*/
-  FutureOr<int> declaredLocalFutureOrInt() async {
+  /*cfe.futureValueType=int*/FutureOr<int> declaredLocalFutureOrInt() async {
     return
         /*cfe.int*/ /*cfe:nnbd.int!*/ 0;
   }
 
   /*cfe:nnbd.futureValueType=Object?*/
-  Object declaredLocalObject() async {
+  /*cfe.futureValueType=Object*/Object declaredLocalObject() async {
     return
         /*cfe.int*/ /*cfe:nnbd.int!*/ 0;
   }
 
-  /*cfe:nnbd.futureValueType=Null*/ omittedLocal() async {}
+  /*futureValueType=Null*/omittedLocal() async {}
 
   Future<int> inferredCalledFutureInt =
-      /*cfe.Future<int> Function()*/
+      /*cfe.Future<int> Function(),futureValueType=int*/
       /*cfe:nnbd.Future<int!>! Function()!,futureValueType=int!*/
       () async {
     return
@@ -63,7 +66,7 @@ method() async {
           ();
 
   FutureOr<int> inferredCalledFutureOrInt =
-      /*cfe.Future<int> Function()*/
+      /*cfe.Future<int> Function(),futureValueType=int*/
       /*cfe:nnbd.Future<int!>! Function()!,futureValueType=int!*/
       () async {
     return
@@ -74,7 +77,7 @@ method() async {
           ();
 
   Future<int> Function() inferredFutureInt =
-      /*cfe.Future<int> Function()*/
+      /*cfe.Future<int> Function(),futureValueType=int*/
       /*cfe:nnbd.Future<int!>! Function()!,futureValueType=int!*/
       () async {
     return
@@ -82,7 +85,7 @@ method() async {
   };
 
   FutureOr<int> Function() inferredFutureOrInt =
-      /*cfe.Future<int> Function()*/
+      /*cfe.Future<int> Function(),futureValueType=int*/
       /*cfe:nnbd.Future<int!>! Function()!,futureValueType=int!*/
       () async {
     return
@@ -90,7 +93,7 @@ method() async {
   };
 
   Object Function() inferredInt =
-      /*cfe.Future<int> Function()*/
+      /*cfe.Future<int> Function(),futureValueType=int*/
       /*cfe:nnbd.Future<int!>! Function()!,futureValueType=int!*/
       () async {
     return
@@ -98,7 +101,7 @@ method() async {
   };
 
   Object Function() inferredNull =
-      /*cfe.Future<Null> Function()*/
+      /*cfe.Future<Null> Function(),futureValueType=Null*/
       /*cfe:nnbd.Future<Null>! Function()!,futureValueType=Null*/
       () async {
     return
@@ -106,7 +109,7 @@ method() async {
   };
 
   Object Function() inferredEmpty =
-      /*cfe.Future<Null> Function()*/
+      /*cfe.Future<Null> Function(),futureValueType=Null*/
       /*cfe:nnbd.Future<Null>! Function()!,futureValueType=Null*/
       () async {};
 }

pkg/front_end/testcases/extensions/async_extensions.dart.weak.expect

@@ -13,7 +13,7 @@ extension Extension on core::int* {
 static method Extension|syncStarMethod(lowered final core::int* #this) → dynamic sync* {}
 static method Extension|get#syncStarMethod(lowered final core::int* #this) → () →* dynamic
   return () → dynamic => self::Extension|syncStarMethod(#this);
-static method Extension|asyncMethod(lowered final core::int* #this) → dynamic async {}
+static method Extension|asyncMethod(lowered final core::int* #this) → dynamic async /* futureValueType= dynamic */ {}
 static method Extension|get#asyncMethod(lowered final core::int* #this) → () →* dynamic
   return () → dynamic => self::Extension|asyncMethod(#this);
 static method Extension|asyncStarMethod(lowered final core::int* #this) → dynamic async* {}

pkg/front_end/testcases/extensions/async_extensions.dart.weak.modular.expect

@@ -13,7 +13,7 @@ extension Extension on core::int* {
 static method Extension|syncStarMethod(lowered final core::int* #this) → dynamic sync* {}
 static method Extension|get#syncStarMethod(lowered final core::int* #this) → () →* dynamic
   return () → dynamic => self::Extension|syncStarMethod(#this);
-static method Extension|asyncMethod(lowered final core::int* #this) → dynamic async {}
+static method Extension|asyncMethod(lowered final core::int* #this) → dynamic async /* futureValueType= dynamic */ {}
 static method Extension|get#asyncMethod(lowered final core::int* #this) → () →* dynamic
   return () → dynamic => self::Extension|asyncMethod(#this);
 static method Extension|asyncStarMethod(lowered final core::int* #this) → dynamic async* {}

pkg/front_end/testcases/extensions/async_extensions.dart.weak.transformed.expect

@@ -25,7 +25,7 @@ static method Extension|syncStarMethod(lowered final core::int* #this) → dynam
 }
 static method Extension|get#syncStarMethod(lowered final core::int* #this) → () →* dynamic
   return () → dynamic => self::Extension|syncStarMethod(#this);
-static method Extension|asyncMethod(lowered final core::int* #this) → dynamic /* originally async */ {
+static method Extension|asyncMethod(lowered final core::int* #this) → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/extensions/deferred_explicit_access.dart.weak.expect

@@ -13,7 +13,7 @@ import "dart:core" as core;
 
 import "org-dartlang-testcase:///deferred_explicit_access_lib.dart" deferred as prefix;
 
-static method main() → dynamic async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
   await LoadLibrary(prefix);
   self::expect(0, let final dynamic #t1 = CheckLibraryIsLoaded(prefix) in def::Extension|staticField);
   self::expect(0, let final dynamic #t2 = CheckLibraryIsLoaded(prefix) in def::Extension|get#property(0));

pkg/front_end/testcases/extensions/deferred_explicit_access.dart.weak.modular.expect

@@ -13,7 +13,7 @@ import "dart:core" as core;
 
 import "org-dartlang-testcase:///deferred_explicit_access_lib.dart" deferred as prefix;
 
-static method main() → dynamic async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
   await LoadLibrary(prefix);
   self::expect(0, let final dynamic #t1 = CheckLibraryIsLoaded(prefix) in def::Extension|staticField);
   self::expect(0, let final dynamic #t2 = CheckLibraryIsLoaded(prefix) in def::Extension|get#property(0));

pkg/front_end/testcases/extensions/deferred_explicit_access.dart.weak.transformed.expect

@@ -14,7 +14,7 @@ import "deferred_explicit_access_lib.dart" as def;
 
 import "org-dartlang-testcase:///deferred_explicit_access_lib.dart" deferred as prefix;
 
-static method main() → dynamic /* originally async */ {
+static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/extensions/deferred_import_hidden.dart.weak.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 
 import "org-dartlang-testcase:///deferred_explicit_access_lib.dart" deferred as prefix hide Extension;
 
-static method main() → dynamic async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
   await LoadLibrary(prefix);
   self::expect(0, let final dynamic #t1 = CheckLibraryIsLoaded(prefix) in def::topLevelField);
   self::expect(42, let final dynamic #t2 = CheckLibraryIsLoaded(prefix) in def::topLevelField = 42);

pkg/front_end/testcases/extensions/deferred_import_hidden.dart.weak.modular.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 
 import "org-dartlang-testcase:///deferred_explicit_access_lib.dart" deferred as prefix hide Extension;
 
-static method main() → dynamic async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
   await LoadLibrary(prefix);
   self::expect(0, let final dynamic #t1 = CheckLibraryIsLoaded(prefix) in def::topLevelField);
   self::expect(42, let final dynamic #t2 = CheckLibraryIsLoaded(prefix) in def::topLevelField = 42);

pkg/front_end/testcases/extensions/deferred_import_hidden.dart.weak.transformed.expect

@@ -6,7 +6,7 @@ import "deferred_explicit_access_lib.dart" as def;
 
 import "org-dartlang-testcase:///deferred_explicit_access_lib.dart" deferred as prefix hide Extension;
 
-static method main() → dynamic /* originally async */ {
+static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/general/control_flow_collection_inference.dart.weak.expect

@@ -1758,7 +1758,7 @@ static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, co
       #t235.{core::Map::[]=}{Invariant}(i, i){(core::int*, core::int*) →* void};
   } =>#t235;
 }
-static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async {
+static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async /* futureValueType= dynamic */ {
   block {
     final core::List<core::int*>* #t236 = <core::int*>[];
     for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1){(core::num*) →* core::int*})

pkg/front_end/testcases/general/control_flow_collection_inference.dart.weak.modular.expect

@@ -1758,7 +1758,7 @@ static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, co
       #t235.{core::Map::[]=}{Invariant}(i, i){(core::int*, core::int*) →* void};
   } =>#t235;
 }
-static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async {
+static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async /* futureValueType= dynamic */ {
   block {
     final core::List<core::int*>* #t236 = <core::int*>[];
     for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1){(core::num*) →* core::int*})

pkg/front_end/testcases/general/control_flow_collection_inference.dart.weak.transformed.expect

@@ -1943,7 +1943,7 @@ static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, co
       #t235.{core::Map::[]=}{Invariant}(i, i){(core::int*, core::int*) →* void};
   } =>#t235;
 }
-static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic /* originally async */ {
+static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/general/flutter_issue64155.dart.weak.expect

@@ -4,7 +4,7 @@ import "dart:core" as core;
 import "dart:async" as asy;
 
 abstract class TestMixin<R extends core::Object* = dynamic, T extends core::Object* = dynamic> extends core::Object /*isMixinDeclaration*/  {
-  method test(covariant-by-class asy::Future<self::TestMixin::R*>* fetch) → asy::Future<self::TestMixin::T*>* async {
+  method test(covariant-by-class asy::Future<self::TestMixin::R*>* fetch) → asy::Future<self::TestMixin::T*>* async /* futureValueType= self::TestMixin::T* */ {
     final self::TestMixin::R* response = await fetch;
     self::TestMixin::T* result;
     if(response is self::Response<dynamic>*) {

pkg/front_end/testcases/general/flutter_issue64155.dart.weak.modular.expect

@@ -4,7 +4,7 @@ import "dart:core" as core;
 import "dart:async" as asy;
 
 abstract class TestMixin<R extends core::Object* = dynamic, T extends core::Object* = dynamic> extends core::Object /*isMixinDeclaration*/  {
-  method test(covariant-by-class asy::Future<self::TestMixin::R*>* fetch) → asy::Future<self::TestMixin::T*>* async {
+  method test(covariant-by-class asy::Future<self::TestMixin::R*>* fetch) → asy::Future<self::TestMixin::T*>* async /* futureValueType= self::TestMixin::T* */ {
     final self::TestMixin::R* response = await fetch;
     self::TestMixin::T* result;
     if(response is self::Response<dynamic>*) {

pkg/front_end/testcases/general/flutter_issue64155.dart.weak.transformed.expect

@@ -5,7 +5,7 @@ import "dart:async" as asy;
 import "dart:_internal" as _in;
 
 abstract class TestMixin<R extends core::Object* = dynamic, T extends core::Object* = dynamic> extends core::Object /*isMixinDeclaration*/  {
-  method test(covariant-by-class asy::Future<self::TestMixin::R*>* fetch) → asy::Future<self::TestMixin::T*>* /* originally async */ {
+  method test(covariant-by-class asy::Future<self::TestMixin::R*>* fetch) → asy::Future<self::TestMixin::T*>* /* futureValueType= self::TestMixin::T* */ /* originally async */ {
     final asy::_Future<self::TestMixin::T*>* :async_future = new asy::_Future::•<self::TestMixin::T*>();
     core::bool* :is_sync = false;
     FutureOr<self::TestMixin::T*>* :return_value;

pkg/front_end/testcases/general/future_or_test.dart.weak.expect

@@ -27,7 +27,7 @@ class B extends core::Object {
   synthetic constructor •() → self::B*
     : super core::Object::•()
     ;
-  method bar() → asy::Future<dynamic>* async 
+  method bar() → asy::Future<dynamic>* async /* futureValueType= dynamic */ 
     return this.{self::B::a}{self::A*}.{self::A::foo}(){() →* dynamic};
   abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
   abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
@@ -45,7 +45,7 @@ class C extends core::Object {
   synthetic constructor •() → self::C*
     : super core::Object::•()
     ;
-  method baz() → asy::Future<core::int*>* async 
+  method baz() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return this.{self::C::b}{self::B*}.{self::B::bar}(){() →* asy::Future<dynamic>*} as{TypeError} FutureOr<core::int*>*;
   abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
   abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf

pkg/front_end/testcases/general/future_or_test.dart.weak.modular.expect

@@ -27,7 +27,7 @@ class B extends core::Object {
   synthetic constructor •() → self::B*
     : super core::Object::•()
     ;
-  method bar() → asy::Future<dynamic>* async 
+  method bar() → asy::Future<dynamic>* async /* futureValueType= dynamic */ 
     return this.{self::B::a}{self::A*}.{self::A::foo}(){() →* dynamic};
   abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
   abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
@@ -45,7 +45,7 @@ class C extends core::Object {
   synthetic constructor •() → self::C*
     : super core::Object::•()
     ;
-  method baz() → asy::Future<core::int*>* async 
+  method baz() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return this.{self::C::b}{self::B*}.{self::B::bar}(){() →* asy::Future<dynamic>*} as{TypeError} FutureOr<core::int*>*;
   abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
   abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf

pkg/front_end/testcases/general/future_or_test.dart.weak.transformed.expect

@@ -27,7 +27,7 @@ class B extends core::Object {
   synthetic constructor •() → self::B*
     : super core::Object::•()
     ;
-  method bar() → asy::Future<dynamic>* /* originally async */ {
+  method bar() → asy::Future<dynamic>* /* futureValueType= dynamic */ /* originally async */ {
     final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
     core::bool* :is_sync = false;
     FutureOr<dynamic>* :return_value;
@@ -70,7 +70,7 @@ class C extends core::Object {
   synthetic constructor •() → self::C*
     : super core::Object::•()
     ;
-  method baz() → asy::Future<core::int*>* /* originally async */ {
+  method baz() → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/general/issue40662.dart.weak.expect

@@ -6,9 +6,9 @@ static method bar(core::int* a, core::List<core::int*>* b) → dynamic {
   self::expect(1.{core::int::unary-}(){() →* core::int*}, a);
   self::expect(1.{core::int::unary-}(){() →* core::int*}, b.{core::List::[]}(0){(core::int*) →* core::int*}.{core::num::-}(2){(core::num*) →* core::int*});
 }
-static method foo(core::int* x) → dynamic async 
+static method foo(core::int* x) → dynamic async /* futureValueType= dynamic */ 
   return self::bar(x.{core::num::-}(1){(core::num*) →* core::int*}, !(x == null) ?{core::List<core::int*>*} <core::int*>[x.{core::num::+}(1){(core::num*) →* core::int*}, x.{core::num::+}(2){(core::num*) →* core::int*}, await null] : null);
-static method main() → void async 
+static method main() → void async /* futureValueType= void */ 
   return await self::foo(0);
 static method expect(dynamic expected, dynamic actual) → dynamic {
   if(!(expected =={core::Object::==}{(core::Object*) →* core::bool*} actual))

pkg/front_end/testcases/general/issue40662.dart.weak.modular.expect

@@ -6,9 +6,9 @@ static method bar(core::int* a, core::List<core::int*>* b) → dynamic {
   self::expect(1.{core::int::unary-}(){() →* core::int*}, a);
   self::expect(1.{core::int::unary-}(){() →* core::int*}, b.{core::List::[]}(0){(core::int*) →* core::int*}.{core::num::-}(2){(core::num*) →* core::int*});
 }
-static method foo(core::int* x) → dynamic async 
+static method foo(core::int* x) → dynamic async /* futureValueType= dynamic */ 
   return self::bar(x.{core::num::-}(1){(core::num*) →* core::int*}, !(x == null) ?{core::List<core::int*>*} <core::int*>[x.{core::num::+}(1){(core::num*) →* core::int*}, x.{core::num::+}(2){(core::num*) →* core::int*}, await null] : null);
-static method main() → void async 
+static method main() → void async /* futureValueType= void */ 
   return await self::foo(0);
 static method expect(dynamic expected, dynamic actual) → dynamic {
   if(!(expected =={core::Object::==}{(core::Object*) →* core::bool*} actual))

pkg/front_end/testcases/general/issue40662.dart.weak.transformed.expect

@@ -8,7 +8,7 @@ static method bar(core::int* a, core::List<core::int*>* b) → dynamic {
   self::expect(1.{core::int::unary-}(){() →* core::int*}, a);
   self::expect(1.{core::int::unary-}(){() →* core::int*}, b.{core::List::[]}(0){(core::int*) →* core::int*}.{core::num::-}(2){(core::num*) →* core::int*});
 }
-static method foo(core::int* x) → dynamic /* originally async */ {
+static method foo(core::int* x) → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   FutureOr<dynamic>* :return_value;
@@ -50,7 +50,7 @@ static method foo(core::int* x) → dynamic /* originally async */ {
   :is_sync = true;
   return :async_future;
 }
-static method main() → void /* originally async */ {
+static method main() → void /* futureValueType= void */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   FutureOr<dynamic>* :return_value;

pkg/front_end/testcases/general/issue42615.dart.weak.expect

@@ -22,7 +22,7 @@ class Class<T extends core::Object* = dynamic> extends core::Object {
 static method method() → dynamic
   return null;
 static method main() → dynamic {
-  new self::Class::•<dynamic>(a: () → FutureOr<core::List<dynamic>*>* async => self::method() as{TypeError} FutureOr<core::List<dynamic>*>*);
+  new self::Class::•<dynamic>(a: () → FutureOr<core::List<dynamic>*>* async /* futureValueType= core::List<dynamic>* */ => self::method() as{TypeError} FutureOr<core::List<dynamic>*>*);
 }
 
 constants  {

pkg/front_end/testcases/general/issue42615.dart.weak.modular.expect

@@ -22,7 +22,7 @@ class Class<T extends core::Object* = dynamic> extends core::Object {
 static method method() → dynamic
   return null;
 static method main() → dynamic {
-  new self::Class::•<dynamic>(a: () → FutureOr<core::List<dynamic>*>* async => self::method() as{TypeError} FutureOr<core::List<dynamic>*>*);
+  new self::Class::•<dynamic>(a: () → FutureOr<core::List<dynamic>*>* async /* futureValueType= core::List<dynamic>* */ => self::method() as{TypeError} FutureOr<core::List<dynamic>*>*);
 }
 
 constants  {

pkg/front_end/testcases/general/issue42615.dart.weak.transformed.expect

@@ -23,7 +23,7 @@ class Class<T extends core::Object* = dynamic> extends core::Object {
 static method method() → dynamic
   return null;
 static method main() → dynamic {
-  new self::Class::•<dynamic>(a: () → FutureOr<core::List<dynamic>*>* /* originally async */ {
+  new self::Class::•<dynamic>(a: () → FutureOr<core::List<dynamic>*>* /* futureValueType= core::List<dynamic>* */ /* originally async */ {
     final asy::_Future<core::List<dynamic>*>* :async_future = new asy::_Future::•<core::List<dynamic>*>();
     core::bool* :is_sync = false;
     FutureOr<core::List<dynamic>*>* :return_value;

pkg/front_end/testcases/general/return_async_promoted.dart

@@ -0,0 +1,13 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'return_async_promoted_lib.dart';
+
+void main() {
+  var f = <T>(o) async => o is int ? o : throw '';
+  var g = () async => legacy();
+}
+
+int? nullable() => null;
+int? nonNullable() => 0;

pkg/front_end/testcases/general/return_async_promoted.dart.textual_outline.expect

@@ -0,0 +1,5 @@
+import 'return_async_promoted_lib.dart';
+
+void main() {}
+int? nullable() => null;
+int? nonNullable() => 0;

pkg/front_end/testcases/general/return_async_promoted.dart.textual_outline_modelled.expect

@@ -0,0 +1,5 @@
+import 'return_async_promoted_lib.dart';
+
+int? nonNullable() => 0;
+int? nullable() => null;
+void main() {}

pkg/front_end/testcases/general/return_async_promoted.dart.weak.expect

@@ -0,0 +1,31 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:async" as asy;
+import "return_async_promoted_lib.dart" as ret;
+
+import "org-dartlang-testcase:///return_async_promoted_lib.dart";
+
+static method main() → void {
+  <T extends core::Object? = dynamic>(dynamic) → asy::Future<core::int> f = <T extends core::Object? = dynamic>(dynamic o) → asy::Future<core::int> async /* futureValueType= core::int */ => o is{ForNonNullableByDefault} core::int ?{core::int} o{core::int} : throw "";
+  () → asy::Future<core::int> g = () → asy::Future<core::int> async /* futureValueType= core::int* */ => ret::legacy();
+}
+static method nullable() → core::int?
+  return null;
+static method nonNullable() → core::int?
+  return 0;
+
+library;
+import self as ret;
+import "dart:core" as core;
+import "dart:async" as asy;
+import "return_async_promoted.dart" as self;
+
+import "org-dartlang-testcase:///return_async_promoted.dart";
+
+static method legacy() → core::int* {
+  <T extends core::Object* = dynamic>(dynamic) →* asy::Future<core::int*>* f = <T extends core::Object* = dynamic>(dynamic o) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => o is core::int* ?{core::int*} o{core::int*} : throw "";
+  () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::nullable();
+  () →* asy::Future<core::int*>* h = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::nonNullable();
+  return null;
+}

pkg/front_end/testcases/general/return_async_promoted.dart.weak.modular.expect

@@ -0,0 +1,31 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:async" as asy;
+import "return_async_promoted_lib.dart" as ret;
+
+import "org-dartlang-testcase:///return_async_promoted_lib.dart";
+
+static method main() → void {
+  <T extends core::Object? = dynamic>(dynamic) → asy::Future<core::int> f = <T extends core::Object? = dynamic>(dynamic o) → asy::Future<core::int> async /* futureValueType= core::int */ => o is{ForNonNullableByDefault} core::int ?{core::int} o{core::int} : throw "";
+  () → asy::Future<core::int> g = () → asy::Future<core::int> async /* futureValueType= core::int* */ => ret::legacy();
+}
+static method nullable() → core::int?
+  return null;
+static method nonNullable() → core::int?
+  return 0;
+
+library;
+import self as ret;
+import "dart:core" as core;
+import "dart:async" as asy;
+import "return_async_promoted.dart" as self;
+
+import "org-dartlang-testcase:///return_async_promoted.dart";
+
+static method legacy() → core::int* {
+  <T extends core::Object* = dynamic>(dynamic) →* asy::Future<core::int*>* f = <T extends core::Object* = dynamic>(dynamic o) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => o is core::int* ?{core::int*} o{core::int*} : throw "";
+  () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::nullable();
+  () →* asy::Future<core::int*>* h = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::nonNullable();
+  return null;
+}

pkg/front_end/testcases/general/return_async_promoted.dart.weak.outline.expect

@@ -0,0 +1,21 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///return_async_promoted_lib.dart";
+
+static method main() → void
+  ;
+static method nullable() → core::int?
+  ;
+static method nonNullable() → core::int?
+  ;
+
+library;
+import self as self2;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///return_async_promoted.dart";
+
+static method legacy() → core::int*
+  ;

pkg/front_end/testcases/general/return_async_promoted.dart.weak.transformed.expect

@@ -0,0 +1,161 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:async" as asy;
+import "return_async_promoted_lib.dart" as ret;
+
+import "org-dartlang-testcase:///return_async_promoted_lib.dart";
+
+static method main() → void {
+  <T extends core::Object? = dynamic>(dynamic) → asy::Future<core::int> f = <T extends core::Object? = dynamic>(dynamic o) → asy::Future<core::int> /* futureValueType= core::int */ /* originally async */ {
+    final asy::_Future<core::int> :async_future = new asy::_Future::•<core::int>();
+    core::bool* :is_sync = false;
+    core::int? :return_value;
+    (dynamic) → dynamic :async_op_then;
+    (core::Object, core::StackTrace) → dynamic :async_op_error;
+    core::int :await_jump_var = 0;
+    dynamic :await_ctx_var;
+    function :async_op(dynamic :result_or_exception, dynamic :stack_trace) → dynamic yielding 
+      try {
+        #L1:
+        {
+          :return_value = o is{ForNonNullableByDefault} core::int ?{core::int} o{core::int} : throw "";
+          break #L1;
+        }
+        asy::_completeWithNoFutureOnAsyncReturn(:async_future, :return_value, :is_sync);
+        return;
+      }
+      on dynamic catch(dynamic exception, core::StackTrace stack_trace) {
+        asy::_completeOnAsyncError(:async_future, exception, stack_trace, :is_sync);
+      }
+    :async_op_then = asy::_asyncThenWrapperHelper(:async_op);
+    :async_op_error = asy::_asyncErrorWrapperHelper(:async_op);
+    :async_op(null, null){() → dynamic};
+    :is_sync = true;
+    return :async_future;
+  };
+  () → asy::Future<core::int> g = () → asy::Future<core::int> /* futureValueType= core::int* */ /* originally async */ {
+    final asy::_Future<core::int> :async_future = new asy::_Future::•<core::int>();
+    core::bool* :is_sync = false;
+    core::int? :return_value;
+    (dynamic) → dynamic :async_op_then;
+    (core::Object, core::StackTrace) → dynamic :async_op_error;
+    core::int :await_jump_var = 0;
+    dynamic :await_ctx_var;
+    function :async_op(dynamic :result_or_exception, dynamic :stack_trace) → dynamic yielding 
+      try {
+        #L2:
+        {
+          :return_value = ret::legacy();
+          break #L2;
+        }
+        asy::_completeWithNoFutureOnAsyncReturn(:async_future, :return_value, :is_sync);
+        return;
+      }
+      on dynamic catch(dynamic exception, core::StackTrace stack_trace) {
+        asy::_completeOnAsyncError(:async_future, exception, stack_trace, :is_sync);
+      }
+    :async_op_then = asy::_asyncThenWrapperHelper(:async_op);
+    :async_op_error = asy::_asyncErrorWrapperHelper(:async_op);
+    :async_op(null, null){() → dynamic};
+    :is_sync = true;
+    return :async_future;
+  };
+}
+static method nullable() → core::int?
+  return null;
+static method nonNullable() → core::int?
+  return 0;
+
+library;
+import self as ret;
+import "dart:core" as core;
+import "dart:async" as asy;
+import "return_async_promoted.dart" as self;
+
+import "org-dartlang-testcase:///return_async_promoted.dart";
+
+static method legacy() → core::int* {
+  <T extends core::Object* = dynamic>(dynamic) →* asy::Future<core::int*>* f = <T extends core::Object* = dynamic>(dynamic o) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
+    final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
+    core::bool* :is_sync = false;
+    core::int? :return_value;
+    (dynamic) →* dynamic :async_op_then;
+    (core::Object*, core::StackTrace*) →* dynamic :async_op_error;
+    core::int* :await_jump_var = 0;
+    dynamic :await_ctx_var;
+    function :async_op(dynamic :result_or_exception, dynamic :stack_trace) → dynamic yielding 
+      try {
+        #L3:
+        {
+          :return_value = o is core::int* ?{core::int*} o{core::int*} : throw "";
+          break #L3;
+        }
+        asy::_completeWithNoFutureOnAsyncReturn(:async_future, :return_value, :is_sync);
+        return;
+      }
+      on dynamic catch(dynamic exception, core::StackTrace* stack_trace) {
+        asy::_completeOnAsyncError(:async_future, exception, stack_trace, :is_sync);
+      }
+    :async_op_then = asy::_asyncThenWrapperHelper(:async_op);
+    :async_op_error = asy::_asyncErrorWrapperHelper(:async_op);
+    :async_op(null, null){() →* dynamic};
+    :is_sync = true;
+    return :async_future;
+  };
+  () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
+    final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
+    core::bool* :is_sync = false;
+    core::int? :return_value;
+    (dynamic) →* dynamic :async_op_then;
+    (core::Object*, core::StackTrace*) →* dynamic :async_op_error;
+    core::int* :await_jump_var = 0;
+    dynamic :await_ctx_var;
+    function :async_op(dynamic :result_or_exception, dynamic :stack_trace) → dynamic yielding 
+      try {
+        #L4:
+        {
+          :return_value = self::nullable();
+          break #L4;
+        }
+        asy::_completeWithNoFutureOnAsyncReturn(:async_future, :return_value, :is_sync);
+        return;
+      }
+      on dynamic catch(dynamic exception, core::StackTrace* stack_trace) {
+        asy::_completeOnAsyncError(:async_future, exception, stack_trace, :is_sync);
+      }
+    :async_op_then = asy::_asyncThenWrapperHelper(:async_op);
+    :async_op_error = asy::_asyncErrorWrapperHelper(:async_op);
+    :async_op(null, null){() →* dynamic};
+    :is_sync = true;
+    return :async_future;
+  };
+  () →* asy::Future<core::int*>* h = () → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
+    final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
+    core::bool* :is_sync = false;
+    core::int? :return_value;
+    (dynamic) →* dynamic :async_op_then;
+    (core::Object*, core::StackTrace*) →* dynamic :async_op_error;
+    core::int* :await_jump_var = 0;
+    dynamic :await_ctx_var;
+    function :async_op(dynamic :result_or_exception, dynamic :stack_trace) → dynamic yielding 
+      try {
+        #L5:
+        {
+          :return_value = self::nonNullable();
+          break #L5;
+        }
+        asy::_completeWithNoFutureOnAsyncReturn(:async_future, :return_value, :is_sync);
+        return;
+      }
+      on dynamic catch(dynamic exception, core::StackTrace* stack_trace) {
+        asy::_completeOnAsyncError(:async_future, exception, stack_trace, :is_sync);
+      }
+    :async_op_then = asy::_asyncThenWrapperHelper(:async_op);
+    :async_op_error = asy::_asyncErrorWrapperHelper(:async_op);
+    :async_op(null, null){() →* dynamic};
+    :is_sync = true;
+    return :async_future;
+  };
+  return null;
+}

pkg/front_end/testcases/general/return_async_promoted_lib.dart

@@ -0,0 +1,14 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// @dart=2.9
+
+import 'return_async_promoted.dart';
+
+int legacy() {
+  var f = <T>(o) async => o is int ? o : throw '';
+  var g = () async => nullable();
+  var h = () async => nonNullable();
+  return null;
+}

pkg/front_end/testcases/incremental/no_outline_change_3.yaml.world.1.expect

@@ -1,7 +1,7 @@
 main = main::main;
 library from "org-dartlang-test:///libA.dart" as libA {
 
-  static method whatever() → dynamic /* originally async */ {
+  static method whatever() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;
@@ -53,7 +53,7 @@ library from "org-dartlang-test:///main.dart" as main {
     abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
     abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
   }
-  static method main() → dynamic /* originally async */ {
+  static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;

pkg/front_end/testcases/incremental/no_outline_change_3.yaml.world.2.expect

@@ -1,7 +1,7 @@
 main = main::main;
 library from "org-dartlang-test:///libA.dart" as libA {
 
-  static method whatever() → dynamic /* originally async */ {
+  static method whatever() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;
@@ -53,7 +53,7 @@ library from "org-dartlang-test:///main.dart" as main {
     abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
     abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
   }
-  static method main() → dynamic /* originally async */ {
+  static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;

pkg/front_end/testcases/incremental/no_outline_change_5.yaml.world.1.expect

@@ -19,7 +19,7 @@ library from "org-dartlang-test:///main.dart" as main {
     abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
     abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
   }
-  static method main() → dynamic /* originally async */ {
+  static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;
@@ -48,7 +48,7 @@ library from "org-dartlang-test:///main.dart" as main {
     :is_sync = true;
     return :async_future;
   }
-  static method /* from org-dartlang-test:///myPart.dart */ whatever() → dynamic /* originally async */ {
+  static method /* from org-dartlang-test:///myPart.dart */ whatever() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;

pkg/front_end/testcases/incremental/no_outline_change_5.yaml.world.2.expect

@@ -19,7 +19,7 @@ library from "org-dartlang-test:///main.dart" as main {
     abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
     abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
   }
-  static method main() → dynamic /* originally async */ {
+  static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;
@@ -48,7 +48,7 @@ library from "org-dartlang-test:///main.dart" as main {
     :is_sync = true;
     return :async_future;
   }
-  static method /* from org-dartlang-test:///myPart.dart */ whatever() → dynamic /* originally async */ {
+  static method /* from org-dartlang-test:///myPart.dart */ whatever() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;

pkg/front_end/testcases/incremental/no_outline_change_5.yaml.world.3.expect

@@ -19,7 +19,7 @@ library from "org-dartlang-test:///main.dart" as main {
     abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
     abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
   }
-  static method main() → dynamic /* originally async */ {
+  static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;
@@ -49,7 +49,7 @@ library from "org-dartlang-test:///main.dart" as main {
     :is_sync = true;
     return :async_future;
   }
-  static method /* from org-dartlang-test:///myPart.dart */ whatever() → dynamic /* originally async */ {
+  static method /* from org-dartlang-test:///myPart.dart */ whatever() → dynamic /* futureValueType= dynamic */ /* originally async */ {
     final dart.async::_Future<dynamic>* :async_future = new dart.async::_Future::•<dynamic>();
     dart.core::bool* :is_sync = false;
     dynamic :return_value;

pkg/front_end/testcases/inference/async_await.dart.weak.expect

@@ -25,7 +25,7 @@ abstract class MyFuture extends core::Object implements asy::Future<core::int*>
   abstract member-signature method asStream() → asy::Stream<core::int*>*; -> asy::Future::asStream
   abstract member-signature method timeout(core::Duration* timeLimit, {covariant-by-class () →* FutureOr<core::int*>* onTimeout = #C1}) → asy::Future<core::int*>*; -> asy::Future::timeout
 }
-static method test() → void async {
+static method test() → void async /* futureValueType= void */ {
   core::int* x0;
   asy::Future<core::int*>* x1;
   asy::Future<asy::Future<core::int*>*>* x2;
@@ -36,25 +36,25 @@ static method test() → void async {
   FutureOr<FutureOr<core::int*>*>* x7;
   FutureOr<self::MyFuture*>* x8;
   self::MyFuture* x9;
-  function test0() → asy::Future<core::int*>* async 
+  function test0() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x0;
-  function test1() → asy::Future<core::int*>* async 
+  function test1() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x1;
-  function test2() → asy::Future<asy::Future<core::int*>*>* async 
+  function test2() → asy::Future<asy::Future<core::int*>*>* async /* futureValueType= asy::Future<core::int*>* */ 
     return x2;
-  function test3() → asy::Future<FutureOr<core::int*>*>* async 
+  function test3() → asy::Future<FutureOr<core::int*>*>* async /* futureValueType= FutureOr<core::int*>* */ 
     return x3;
-  function test4() → asy::Future<self::MyFuture*>* async 
+  function test4() → asy::Future<self::MyFuture*>* async /* futureValueType= self::MyFuture* */ 
     return x4;
-  function test5() → asy::Future<core::int*>* async 
+  function test5() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x5;
-  function test6() → asy::Future<asy::Future<core::int*>*>* async 
+  function test6() → asy::Future<asy::Future<core::int*>*>* async /* futureValueType= asy::Future<core::int*>* */ 
     return x6;
-  function test7() → asy::Future<FutureOr<core::int*>*>* async 
+  function test7() → asy::Future<FutureOr<core::int*>*>* async /* futureValueType= FutureOr<core::int*>* */ 
     return x7;
-  function test8() → asy::Future<self::MyFuture*>* async 
+  function test8() → asy::Future<self::MyFuture*>* async /* futureValueType= self::MyFuture* */ 
     return x8;
-  function test9() → asy::Future<core::int*>* async 
+  function test9() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x9;
   core::int* y0 = await x0;
   core::int* y1 = await x1;

pkg/front_end/testcases/inference/async_await.dart.weak.modular.expect

@@ -25,7 +25,7 @@ abstract class MyFuture extends core::Object implements asy::Future<core::int*>
   abstract member-signature method asStream() → asy::Stream<core::int*>*; -> asy::Future::asStream
   abstract member-signature method timeout(core::Duration* timeLimit, {covariant-by-class () →* FutureOr<core::int*>* onTimeout = #C1}) → asy::Future<core::int*>*; -> asy::Future::timeout
 }
-static method test() → void async {
+static method test() → void async /* futureValueType= void */ {
   core::int* x0;
   asy::Future<core::int*>* x1;
   asy::Future<asy::Future<core::int*>*>* x2;
@@ -36,25 +36,25 @@ static method test() → void async {
   FutureOr<FutureOr<core::int*>*>* x7;
   FutureOr<self::MyFuture*>* x8;
   self::MyFuture* x9;
-  function test0() → asy::Future<core::int*>* async 
+  function test0() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x0;
-  function test1() → asy::Future<core::int*>* async 
+  function test1() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x1;
-  function test2() → asy::Future<asy::Future<core::int*>*>* async 
+  function test2() → asy::Future<asy::Future<core::int*>*>* async /* futureValueType= asy::Future<core::int*>* */ 
     return x2;
-  function test3() → asy::Future<FutureOr<core::int*>*>* async 
+  function test3() → asy::Future<FutureOr<core::int*>*>* async /* futureValueType= FutureOr<core::int*>* */ 
     return x3;
-  function test4() → asy::Future<self::MyFuture*>* async 
+  function test4() → asy::Future<self::MyFuture*>* async /* futureValueType= self::MyFuture* */ 
     return x4;
-  function test5() → asy::Future<core::int*>* async 
+  function test5() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x5;
-  function test6() → asy::Future<asy::Future<core::int*>*>* async 
+  function test6() → asy::Future<asy::Future<core::int*>*>* async /* futureValueType= asy::Future<core::int*>* */ 
     return x6;
-  function test7() → asy::Future<FutureOr<core::int*>*>* async 
+  function test7() → asy::Future<FutureOr<core::int*>*>* async /* futureValueType= FutureOr<core::int*>* */ 
     return x7;
-  function test8() → asy::Future<self::MyFuture*>* async 
+  function test8() → asy::Future<self::MyFuture*>* async /* futureValueType= self::MyFuture* */ 
     return x8;
-  function test9() → asy::Future<core::int*>* async 
+  function test9() → asy::Future<core::int*>* async /* futureValueType= core::int* */ 
     return x9;
   core::int* y0 = await x0;
   core::int* y1 = await x1;

pkg/front_end/testcases/inference/async_await.dart.weak.transformed.expect

@@ -26,7 +26,7 @@ abstract class MyFuture extends core::Object implements asy::Future<core::int*>
   abstract member-signature method asStream() → asy::Stream<core::int*>*; -> asy::Future::asStream
   abstract member-signature method timeout(core::Duration* timeLimit, {covariant-by-class () →* FutureOr<core::int*>* onTimeout = #C1}) → asy::Future<core::int*>*; -> asy::Future::timeout
 }
-static method test() → void /* originally async */ {
+static method test() → void /* futureValueType= void */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;
@@ -49,7 +49,7 @@ static method test() → void /* originally async */ {
         FutureOr<FutureOr<core::int*>*>* x7;
         FutureOr<self::MyFuture*>* x8;
         self::MyFuture* x9;
-        function test0() → asy::Future<core::int*>* /* originally async */ {
+        function test0() → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
           final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
           core::bool* :is_sync = false;
           core::int? :return_value;
@@ -76,7 +76,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test1() → asy::Future<core::int*>* /* originally async */ {
+        function test1() → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
           final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
           core::bool* :is_sync = false;
           FutureOr<core::int*>* :return_value;
@@ -103,7 +103,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test2() → asy::Future<asy::Future<core::int*>*>* /* originally async */ {
+        function test2() → asy::Future<asy::Future<core::int*>*>* /* futureValueType= asy::Future<core::int*>* */ /* originally async */ {
           final asy::_Future<asy::Future<core::int*>*>* :async_future = new asy::_Future::•<asy::Future<core::int*>*>();
           core::bool* :is_sync = false;
           FutureOr<asy::Future<core::int*>*>* :return_value;
@@ -130,7 +130,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test3() → asy::Future<FutureOr<core::int*>*>* /* originally async */ {
+        function test3() → asy::Future<FutureOr<core::int*>*>* /* futureValueType= FutureOr<core::int*>* */ /* originally async */ {
           final asy::_Future<FutureOr<core::int*>*>* :async_future = new asy::_Future::•<FutureOr<core::int*>*>();
           core::bool* :is_sync = false;
           FutureOr<FutureOr<core::int*>*>* :return_value;
@@ -157,7 +157,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test4() → asy::Future<self::MyFuture*>* /* originally async */ {
+        function test4() → asy::Future<self::MyFuture*>* /* futureValueType= self::MyFuture* */ /* originally async */ {
           final asy::_Future<self::MyFuture*>* :async_future = new asy::_Future::•<self::MyFuture*>();
           core::bool* :is_sync = false;
           FutureOr<self::MyFuture*>* :return_value;
@@ -184,7 +184,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test5() → asy::Future<core::int*>* /* originally async */ {
+        function test5() → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
           final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
           core::bool* :is_sync = false;
           FutureOr<core::int*>* :return_value;
@@ -211,7 +211,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test6() → asy::Future<asy::Future<core::int*>*>* /* originally async */ {
+        function test6() → asy::Future<asy::Future<core::int*>*>* /* futureValueType= asy::Future<core::int*>* */ /* originally async */ {
           final asy::_Future<asy::Future<core::int*>*>* :async_future = new asy::_Future::•<asy::Future<core::int*>*>();
           core::bool* :is_sync = false;
           FutureOr<asy::Future<core::int*>*>* :return_value;
@@ -238,7 +238,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test7() → asy::Future<FutureOr<core::int*>*>* /* originally async */ {
+        function test7() → asy::Future<FutureOr<core::int*>*>* /* futureValueType= FutureOr<core::int*>* */ /* originally async */ {
           final asy::_Future<FutureOr<core::int*>*>* :async_future = new asy::_Future::•<FutureOr<core::int*>*>();
           core::bool* :is_sync = false;
           FutureOr<FutureOr<core::int*>*>* :return_value;
@@ -265,7 +265,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test8() → asy::Future<self::MyFuture*>* /* originally async */ {
+        function test8() → asy::Future<self::MyFuture*>* /* futureValueType= self::MyFuture* */ /* originally async */ {
           final asy::_Future<self::MyFuture*>* :async_future = new asy::_Future::•<self::MyFuture*>();
           core::bool* :is_sync = false;
           FutureOr<self::MyFuture*>* :return_value;
@@ -292,7 +292,7 @@ static method test() → void /* originally async */ {
           :is_sync = true;
           return :async_future;
         }
-        function test9() → asy::Future<core::int*>* /* originally async */ {
+        function test9() → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
           final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
           core::bool* :is_sync = false;
           FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/async_closure_return_type_flatten.dart.weak.expect

@@ -7,7 +7,7 @@ import "dart:async";
 
 static field asy::Future<core::int*>* futureInt = null;
 static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* => self::futureInt;
-static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async => self::futureInt;
+static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::futureInt;
 static method main() → dynamic {
   self::f;
   self::g;

pkg/front_end/testcases/inference/async_closure_return_type_flatten.dart.weak.modular.expect

@@ -7,7 +7,7 @@ import "dart:async";
 
 static field asy::Future<core::int*>* futureInt = null;
 static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* => self::futureInt;
-static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async => self::futureInt;
+static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::futureInt;
 static method main() → dynamic {
   self::f;
   self::g;

pkg/front_end/testcases/inference/async_closure_return_type_flatten.dart.weak.transformed.expect

@@ -7,7 +7,7 @@ import "dart:async";
 
 static field asy::Future<core::int*>* futureInt = null;
 static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* => self::futureInt;
-static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* /* originally async */ {
+static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
   final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
   core::bool* :is_sync = false;
   FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/async_closure_return_type_future.dart.weak.expect

@@ -3,7 +3,7 @@ import self as self;
 import "dart:async" as asy;
 import "dart:core" as core;
 
-static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* async => 0;
+static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 0;
 static method main() → dynamic {
   self::f;
 }

pkg/front_end/testcases/inference/async_closure_return_type_future.dart.weak.modular.expect

@@ -3,7 +3,7 @@ import self as self;
 import "dart:async" as asy;
 import "dart:core" as core;
 
-static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* async => 0;
+static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 0;
 static method main() → dynamic {
   self::f;
 }

pkg/front_end/testcases/inference/async_closure_return_type_future.dart.weak.transformed.expect

@@ -3,7 +3,7 @@ import self as self;
 import "dart:async" as asy;
 import "dart:core" as core;
 
-static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* /* originally async */ {
+static field () →* asy::Future<core::int*>* f = () → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
   final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
   core::bool* :is_sync = false;
   core::int? :return_value;

pkg/front_end/testcases/inference/async_closure_return_type_future_or.dart.weak.expect

@@ -7,7 +7,7 @@ import "dart:async";
 
 static field FutureOr<core::int*>* futureOrInt = null;
 static field () →* FutureOr<core::int*>* f = () → FutureOr<core::int*>* => self::futureOrInt;
-static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async => self::futureOrInt;
+static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::futureOrInt;
 static method main() → dynamic {
   self::f;
   self::g;

pkg/front_end/testcases/inference/async_closure_return_type_future_or.dart.weak.modular.expect

@@ -7,7 +7,7 @@ import "dart:async";
 
 static field FutureOr<core::int*>* futureOrInt = null;
 static field () →* FutureOr<core::int*>* f = () → FutureOr<core::int*>* => self::futureOrInt;
-static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async => self::futureOrInt;
+static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* async /* futureValueType= core::int* */ => self::futureOrInt;
 static method main() → dynamic {
   self::f;
   self::g;

pkg/front_end/testcases/inference/async_closure_return_type_future_or.dart.weak.transformed.expect

@@ -7,7 +7,7 @@ import "dart:async";
 
 static field FutureOr<core::int*>* futureOrInt = null;
 static field () →* FutureOr<core::int*>* f = () → FutureOr<core::int*>* => self::futureOrInt;
-static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* /* originally async */ {
+static field () →* asy::Future<core::int*>* g = () → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
   final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
   core::bool* :is_sync = false;
   FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/block_bodied_lambdas_async_all_returns_are_futures.dart.weak.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async /* futureValueType= core::num* */ {
     if(math::Random::•().{math::Random::nextBool}(){() →* core::bool*}) {
       return asy::Future::value<core::int*>(1);
     }

pkg/front_end/testcases/inference/block_bodied_lambdas_async_all_returns_are_futures.dart.weak.modular.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async /* futureValueType= core::num* */ {
     if(math::Random::•().{math::Random::nextBool}(){() →* core::bool*}) {
       return asy::Future::value<core::int*>(1);
     }

pkg/front_end/testcases/inference/block_bodied_lambdas_async_all_returns_are_futures.dart.weak.transformed.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* /* originally async */ {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* /* futureValueType= core::num* */ /* originally async */ {
     final asy::_Future<core::num*>* :async_future = new asy::_Future::•<core::num*>();
     core::bool* :is_sync = false;
     FutureOr<core::num*>* :return_value;

pkg/front_end/testcases/inference/block_bodied_lambdas_async_all_returns_are_values.dart.weak.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async /* futureValueType= core::num* */ {
     if(math::Random::•().{math::Random::nextBool}(){() →* core::bool*}) {
       return 1;
     }

pkg/front_end/testcases/inference/block_bodied_lambdas_async_all_returns_are_values.dart.weak.modular.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async /* futureValueType= core::num* */ {
     if(math::Random::•().{math::Random::nextBool}(){() →* core::bool*}) {
       return 1;
     }

pkg/front_end/testcases/inference/block_bodied_lambdas_async_all_returns_are_values.dart.weak.transformed.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* /* originally async */ {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* /* futureValueType= core::num* */ /* originally async */ {
     final asy::_Future<core::num*>* :async_future = new asy::_Future::•<core::num*>();
     core::bool* :is_sync = false;
     core::num? :return_value;

pkg/front_end/testcases/inference/block_bodied_lambdas_async_mix_of_values_and_futures.dart.weak.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async /* futureValueType= core::num* */ {
     if(math::Random::•().{math::Random::nextBool}(){() →* core::bool*}) {
       return asy::Future::value<core::int*>(1);
     }

pkg/front_end/testcases/inference/block_bodied_lambdas_async_mix_of_values_and_futures.dart.weak.modular.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* async /* futureValueType= core::num* */ {
     if(math::Random::•().{math::Random::nextBool}(){() →* core::bool*}) {
       return asy::Future::value<core::int*>(1);
     }

pkg/front_end/testcases/inference/block_bodied_lambdas_async_mix_of_values_and_futures.dart.weak.transformed.expect

@@ -8,7 +8,7 @@ import "dart:async";
 import "dart:math" show Random;
 
 static method test() → dynamic {
-  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* /* originally async */ {
+  () →* asy::Future<core::num*>* f = () → asy::Future<core::num*>* /* futureValueType= core::num* */ /* originally async */ {
     final asy::_Future<core::num*>* :async_future = new asy::_Future::•<core::num*>();
     core::bool* :is_sync = false;
     FutureOr<core::num*>* :return_value;

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_async.dart.weak.expect

@@ -5,8 +5,8 @@ import "dart:core" as core;
 
 import "dart:async";
 
-static method main() → dynamic async {
-  () →* asy::Future<Null>* f = () → asy::Future<Null>* async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
+  () →* asy::Future<Null>* f = () → asy::Future<Null>* async /* futureValueType= Null */ {
     return null;
   };
   asy::Future<dynamic>* y = f(){() →* asy::Future<Null>*};

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_async.dart.weak.modular.expect

@@ -5,8 +5,8 @@ import "dart:core" as core;
 
 import "dart:async";
 
-static method main() → dynamic async {
-  () →* asy::Future<Null>* f = () → asy::Future<Null>* async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
+  () →* asy::Future<Null>* f = () → asy::Future<Null>* async /* futureValueType= Null */ {
     return null;
   };
   asy::Future<dynamic>* y = f(){() →* asy::Future<Null>*};

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_async.dart.weak.transformed.expect

@@ -6,7 +6,7 @@ import "dart:_internal" as _in;
 
 import "dart:async";
 
-static method main() → dynamic /* originally async */ {
+static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;
@@ -19,7 +19,7 @@ static method main() → dynamic /* originally async */ {
     try {
       #L1:
       {
-        () →* asy::Future<Null>* f = () → asy::Future<Null>* /* originally async */ {
+        () →* asy::Future<Null>* f = () → asy::Future<Null>* /* futureValueType= Null */ /* originally async */ {
           final asy::_Future<Null>* :async_future = new asy::_Future::•<Null>();
           core::bool* :is_sync = false;
           FutureOr<Null>* :return_value;

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_async_star.dart.weak.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 
 import "dart:async";
 
-static method main() → dynamic async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
   () →* asy::Stream<Null>* f = () → asy::Stream<Null>* async* {
     yield null;
   };

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_async_star.dart.weak.modular.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 
 import "dart:async";
 
-static method main() → dynamic async {
+static method main() → dynamic async /* futureValueType= dynamic */ {
   () →* asy::Stream<Null>* f = () → asy::Stream<Null>* async* {
     yield null;
   };

pkg/front_end/testcases/inference/block_bodied_lambdas_infer_bottom_async_star.dart.weak.transformed.expect

@@ -6,7 +6,7 @@ import "dart:_internal" as _in;
 
 import "dart:async";
 
-static method main() → dynamic /* originally async */ {
+static method main() → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/inference/downwards_inference_async_await.dart.weak.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 
 import "dart:async";
 
-static method main() → asy::Future<dynamic>* async {
+static method main() → asy::Future<dynamic>* async /* futureValueType= dynamic */ {
   dynamic d;
   core::List<core::int*>* l0 = await<core::int*>[d as{TypeError,ForDynamic} core::int*];
   core::List<core::int*>* l1 = await asy::Future::value<core::List<core::int*>*>(<core::int*>[d as{TypeError,ForDynamic} core::int*]);

pkg/front_end/testcases/inference/downwards_inference_async_await.dart.weak.modular.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 
 import "dart:async";
 
-static method main() → asy::Future<dynamic>* async {
+static method main() → asy::Future<dynamic>* async /* futureValueType= dynamic */ {
   dynamic d;
   core::List<core::int*>* l0 = await<core::int*>[d as{TypeError,ForDynamic} core::int*];
   core::List<core::int*>* l1 = await asy::Future::value<core::List<core::int*>*>(<core::int*>[d as{TypeError,ForDynamic} core::int*]);

pkg/front_end/testcases/inference/downwards_inference_async_await.dart.weak.transformed.expect

@@ -6,7 +6,7 @@ import "dart:_internal" as _in;
 
 import "dart:async";
 
-static method main() → asy::Future<dynamic>* /* originally async */ {
+static method main() → asy::Future<dynamic>* /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/inference/downwards_inference_for_each.dart.weak.expect

@@ -58,7 +58,7 @@ abstract class MyStream<T extends core::Object* = dynamic> extends asy::Stream<s
 }
 static method F<T extends core::Object* = dynamic>() → self::F::T*
   return null;
-static method f() → asy::Future<dynamic>* async {
+static method f() → asy::Future<dynamic>* async /* futureValueType= dynamic */ {
   dynamic d;
   core::Object* o;
   for (dynamic x in self::F<core::Iterable<dynamic>*>()) {
@@ -86,7 +86,7 @@ static method f() → asy::Future<dynamic>* async {
     o = #t4;
   }
 }
-static method main() → asy::Future<dynamic>* async {
+static method main() → asy::Future<dynamic>* async /* futureValueType= dynamic */ {
   for (core::int* x in <core::int*>[1, 2, 3]) {
   }
   for (core::num* x in <core::num*>[1, 2, 3]) {

pkg/front_end/testcases/inference/downwards_inference_for_each.dart.weak.modular.expect

@@ -58,7 +58,7 @@ abstract class MyStream<T extends core::Object* = dynamic> extends asy::Stream<s
 }
 static method F<T extends core::Object* = dynamic>() → self::F::T*
   return null;
-static method f() → asy::Future<dynamic>* async {
+static method f() → asy::Future<dynamic>* async /* futureValueType= dynamic */ {
   dynamic d;
   core::Object* o;
   for (dynamic x in self::F<core::Iterable<dynamic>*>()) {
@@ -86,7 +86,7 @@ static method f() → asy::Future<dynamic>* async {
     o = #t4;
   }
 }
-static method main() → asy::Future<dynamic>* async {
+static method main() → asy::Future<dynamic>* async /* futureValueType= dynamic */ {
   for (core::int* x in <core::int*>[1, 2, 3]) {
   }
   for (core::num* x in <core::num*>[1, 2, 3]) {

pkg/front_end/testcases/inference/downwards_inference_for_each.dart.weak.transformed.expect

@@ -59,7 +59,7 @@ abstract class MyStream<T extends core::Object* = dynamic> extends asy::Stream<s
 }
 static method F<T extends core::Object* = dynamic>() → self::F::T*
   return null;
-static method f() → asy::Future<dynamic>* /* originally async */ {
+static method f() → asy::Future<dynamic>* /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;
@@ -238,7 +238,7 @@ static method f() → asy::Future<dynamic>* /* originally async */ {
   :is_sync = true;
   return :async_future;
 }
-static method main() → asy::Future<dynamic>* /* originally async */ {
+static method main() → asy::Future<dynamic>* /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.weak.expect

@@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;
 import "dart:async" as asy;
 
-static method test() → dynamic async {
+static method test() → dynamic async /* futureValueType= dynamic */ {
   core::Object* o;
   for (dynamic x in o as{TypeError} core::Iterable<dynamic>*) {
   }

pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.weak.modular.expect

@@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;
 import "dart:async" as asy;
 
-static method test() → dynamic async {
+static method test() → dynamic async /* futureValueType= dynamic */ {
   core::Object* o;
   for (dynamic x in o as{TypeError} core::Iterable<dynamic>*) {
   }

pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.weak.transformed.expect

@@ -4,7 +4,7 @@ import "dart:async" as asy;
 import "dart:core" as core;
 import "dart:_internal" as _in;
 
-static method test() → dynamic /* originally async */ {
+static method test() → dynamic /* futureValueType= dynamic */ /* originally async */ {
   final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
   core::bool* :is_sync = false;
   dynamic :return_value;

pkg/front_end/testcases/inference/future_then.dart.weak.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then.dart.weak.modular.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -64,7 +64,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -93,7 +93,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -120,7 +120,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -151,7 +151,7 @@ static method test() → void {
   asy::Future<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;
@@ -178,7 +178,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_2.dart.weak.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_2.dart.weak.modular.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_2.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -64,7 +64,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -93,7 +93,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -120,7 +120,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -151,7 +151,7 @@ static method test() → void {
   asy::Future<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;
@@ -178,7 +178,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_3.dart.weak.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_3.dart.weak.modular.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_3.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -64,7 +64,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -93,7 +93,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -120,7 +120,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -151,7 +151,7 @@ static method test() → void {
   self::MyFuture<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;
@@ -178,7 +178,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_4.dart.weak.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_4.dart.weak.modular.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   self::MyFuture<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_4.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
-  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -64,7 +64,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -93,7 +93,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t3 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -120,7 +120,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t4 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -151,7 +151,7 @@ static method test() → void {
   self::MyFuture<core::int*>* t6 = f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t7 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;
@@ -178,7 +178,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  self::MyFuture<core::int*>* t8 = f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_5.dart.weak.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   asy::Future<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t5 = f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t6 = f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_5.dart.weak.modular.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   asy::Future<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t5 = f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t6 = f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => new self::MyFuture::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_5.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   asy::Future<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -64,7 +64,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -93,7 +93,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -120,7 +120,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -151,7 +151,7 @@ static method test() → void {
   asy::Future<core::int*>* t6 = f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* {
     return new self::MyFuture::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;
@@ -178,7 +178,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_6.dart.weak.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   asy::Future<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t5 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t6 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_6.dart.weak.modular.expect

@@ -34,20 +34,20 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   asy::Future<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => await asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return await asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => 3){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return 3;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t5 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
   asy::Future<core::int*>* t6 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async {
+  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => asy::Future::value<core::int*>(3)){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
+  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* async /* futureValueType= core::int* */ {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
 }

pkg/front_end/testcases/inference/future_then_6.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   asy::Future<dynamic>* f;
-  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t1 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -64,7 +64,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t2 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -93,7 +93,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t3 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -120,7 +120,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t4 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -151,7 +151,7 @@ static method test() → void {
   asy::Future<core::int*>* t6 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* {
     return asy::Future::value<core::int*>(3);
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t7 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;
@@ -178,7 +178,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((dynamic) →* FutureOr<core::int*>*, {onError: core::Function*}) →* asy::Future<core::int*>*};
-  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t8 = f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_conditional.dart.weak.expect

@@ -34,8 +34,8 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* async => x ?{core::int*} 2 : await asy::Future::value<core::int*>(3)){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => x ?{core::int*} 2 : await asy::Future::value<core::int*>(3)){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* async /* futureValueType= core::int* */ {
     return (await x ?{core::Object*} 2 : asy::Future::value<core::int*>(3)) as{TypeError} FutureOr<core::int*>*;
   }){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* => (x ?{core::Object*} 2 : asy::Future::value<core::int*>(3)) as{TypeError} FutureOr<core::int*>*){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};

pkg/front_end/testcases/inference/future_then_conditional.dart.weak.modular.expect

@@ -34,8 +34,8 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* async => x ?{core::int*} 2 : await asy::Future::value<core::int*>(3)){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => x ?{core::int*} 2 : await asy::Future::value<core::int*>(3)){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* async /* futureValueType= core::int* */ {
     return (await x ?{core::Object*} 2 : asy::Future::value<core::int*>(3)) as{TypeError} FutureOr<core::int*>*;
   }){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* => (x ?{core::Object*} 2 : asy::Future::value<core::int*>(3)) as{TypeError} FutureOr<core::int*>*){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};

pkg/front_end/testcases/inference/future_then_conditional.dart.weak.transformed.expect

@@ -35,7 +35,7 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     core::int? :return_value;
@@ -71,7 +71,7 @@ static method test() → void {
     :is_sync = true;
     return :async_future;
   }){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* /* originally async */ {
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* /* futureValueType= core::int* */ /* originally async */ {
     final asy::_Future<core::int*>* :async_future = new asy::_Future::•<core::int*>();
     core::bool* :is_sync = false;
     FutureOr<core::int*>* :return_value;

pkg/front_end/testcases/inference/future_then_conditional_2.dart.weak.expect

@@ -34,8 +34,8 @@ class MyFuture<T extends core::Object* = dynamic> extends core::Object implement
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
-  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* async => x ?{core::int*} 2 : await new self::MyFuture::value<core::int*>(3)){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
-  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* async {
+  asy::Future<core::int*>* t1 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → asy::Future<core::int*>* async /* futureValueType= core::int* */ => x ?{core::int*} 2 : await new self::MyFuture::value<core::int*>(3)){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
+  asy::Future<core::int*>* t2 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* async /* futureValueType= core::int* */ {
     return (await x ?{core::Object*} 2 : new self::MyFuture::value<core::int*>(3)) as{TypeError} FutureOr<core::int*>*;
   }){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};
   asy::Future<core::int*>* t5 = f.{self::MyFuture::then}<core::int*>((core::bool* x) → FutureOr<core::int*>* => (x ?{core::Object*} 2 : new self::MyFuture::value<core::int*>(3)) as{TypeError} FutureOr<core::int*>*){((core::bool*) →* FutureOr<core::int*>*, {onError: core::Function*}) →* self::MyFuture<core::int*>*};