diff --git a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
index 276b71e091b..c3af5339c9f 100644
--- a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
@@ -6379,14 +6379,6 @@ const MessageCode messageNonInstanceTypeVariableUse = const MessageCode(
     analyzerCodes: <String>["TYPE_PARAMETER_REFERENCED_BY_STATIC"],
     message: r"""Can only use type variables in instance methods.""");
 
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Null> codeNonNullAwareSpreadIsNull = messageNonNullAwareSpreadIsNull;
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const MessageCode messageNonNullAwareSpreadIsNull = const MessageCode(
-    "NonNullAwareSpreadIsNull",
-    message: r"""Can't spread a value with static type Null.""");
-
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(String name)>
     templateNonNullableLateDefinitelyAssignedError =
diff --git a/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart b/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart
index 7bb345392ce..6927bdd7183 100644
--- a/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart
+++ b/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart
@@ -2196,6 +2196,33 @@ Message _withArgumentsMixinInferenceNoMatchingClass(
       arguments: {'name': name, 'name2': name2, 'type': _type});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(DartType _type, bool isNonNullableByDefault)>
+    templateNonNullAwareSpreadIsNull = const Template<
+            Message Function(DartType _type, bool isNonNullableByDefault)>(
+        messageTemplate: r"""Can't spread a value with static type '#type'.""",
+        withArguments: _withArgumentsNonNullAwareSpreadIsNull);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(DartType _type, bool isNonNullableByDefault)>
+    codeNonNullAwareSpreadIsNull =
+    const Code<Message Function(DartType _type, bool isNonNullableByDefault)>(
+  "NonNullAwareSpreadIsNull",
+  templateNonNullAwareSpreadIsNull,
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsNonNullAwareSpreadIsNull(
+    DartType _type, bool isNonNullableByDefault) {
+  TypeLabeler labeler = new TypeLabeler(isNonNullableByDefault);
+  List<Object> typeParts = labeler.labelType(_type);
+  String type = typeParts.join();
+  return new Message(codeNonNullAwareSpreadIsNull,
+      message: """Can't spread a value with static type '${type}'.""" +
+          labeler.originMessages,
+      arguments: {'type': _type});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
         Message Function(
diff --git a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
index d9bdf4b4978..8ed64425338 100644
--- a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
@@ -1328,21 +1328,27 @@ class InferenceVisitor
   }
 
   DartType getSpreadElementType(DartType spreadType, bool isNullAware) {
-    if (spreadType is InterfaceType) {
-      if (spreadType.classNode == inferrer.coreTypes.nullClass) {
-        if (inferrer.isNonNullableByDefault) {
-          return isNullAware ? const NeverType(Nullability.nonNullable) : null;
-        } else {
-          return isNullAware ? spreadType : null;
-        }
+    DartType typeBound = inferrer.resolveTypeParameter(spreadType);
+    if (inferrer.coreTypes.isNull(typeBound)) {
+      if (inferrer.isNonNullableByDefault) {
+        return isNullAware ? const NeverType(Nullability.nonNullable) : null;
+      } else {
+        return isNullAware ? inferrer.coreTypes.nullType : null;
       }
+    }
+    if (typeBound is InterfaceType) {
       List<DartType> supertypeArguments = inferrer.typeSchemaEnvironment
           .getTypeArgumentsAsInstanceOf(
-              spreadType, inferrer.coreTypes.iterableClass);
-      if (supertypeArguments == null) return null;
+              typeBound, inferrer.coreTypes.iterableClass);
+      if (supertypeArguments == null) {
+        return null;
+      }
       return supertypeArguments.single;
+    } else if (spreadType is DynamicType) {
+      return const DynamicType();
+    } else if (inferrer.coreTypes.isBottom(spreadType)) {
+      return const NeverType(Nullability.nonNullable);
     }
-    if (spreadType is DynamicType) return const DynamicType();
     return null;
   }
 
@@ -1374,11 +1380,12 @@ class InferenceVisitor
         DartType spreadElementType =
             getSpreadElementType(spreadType, element.isNullAware);
         if (spreadElementType == null) {
-          if (spreadType is InterfaceType &&
-              spreadType.classNode == inferrer.coreTypes.nullClass &&
+          if (inferrer.coreTypes
+                  .isNull(inferrer.resolveTypeParameter(spreadType)) &&
               !element.isNullAware) {
             replacement = inferrer.helper.buildProblem(
-                messageNonNullAwareSpreadIsNull,
+                templateNonNullAwareSpreadIsNull.withArguments(
+                    spreadType, inferrer.isNonNullableByDefault),
                 element.expression.fileOffset,
                 1);
           } else {
@@ -1734,28 +1741,28 @@ class InferenceVisitor
   // is a function type, the original values in output are preserved.
   void storeSpreadMapEntryElementTypes(DartType spreadMapEntryType,
       bool isNullAware, List<DartType> output, int offset) {
-    if (spreadMapEntryType is InterfaceType) {
-      if (spreadMapEntryType.classNode == inferrer.coreTypes.nullClass) {
-        if (isNullAware) {
-          if (inferrer.isNonNullableByDefault) {
-            output[offset] =
-                output[offset + 1] = const NeverType(Nullability.nonNullable);
-          } else {
-            output[offset] = output[offset + 1] = spreadMapEntryType;
-          }
-        }
-      } else {
-        List<DartType> supertypeArguments = inferrer.typeSchemaEnvironment
-            .getTypeArgumentsAsInstanceOf(
-                spreadMapEntryType, inferrer.coreTypes.mapClass);
-        if (supertypeArguments != null) {
-          output[offset] = supertypeArguments[0];
-          output[offset + 1] = supertypeArguments[1];
+    DartType typeBound = inferrer.resolveTypeParameter(spreadMapEntryType);
+    if (inferrer.coreTypes.isNull(typeBound)) {
+      if (isNullAware) {
+        if (inferrer.isNonNullableByDefault) {
+          output[offset] =
+              output[offset + 1] = const NeverType(Nullability.nonNullable);
+        } else {
+          output[offset] = output[offset + 1] = inferrer.coreTypes.nullType;
         }
       }
-    }
-    if (spreadMapEntryType is DynamicType) {
+    } else if (typeBound is InterfaceType) {
+      List<DartType> supertypeArguments = inferrer.typeSchemaEnvironment
+          .getTypeArgumentsAsInstanceOf(typeBound, inferrer.coreTypes.mapClass);
+      if (supertypeArguments != null) {
+        output[offset] = supertypeArguments[0];
+        output[offset + 1] = supertypeArguments[1];
+      }
+    } else if (spreadMapEntryType is DynamicType) {
       output[offset] = output[offset + 1] = const DynamicType();
+    } else if (inferrer.coreTypes.isBottom(spreadMapEntryType)) {
+      output[offset] =
+          output[offset + 1] = const NeverType(Nullability.nonNullable);
     }
   }
 
@@ -1800,12 +1807,15 @@ class InferenceVisitor
       MapEntry replacement = entry;
       if (typeChecksNeeded) {
         if (actualKeyType == null) {
-          if (spreadType is InterfaceType &&
-              spreadType.classNode == inferrer.coreTypes.nullClass &&
+          if (inferrer.coreTypes
+                  .isNull(inferrer.resolveTypeParameter(spreadType)) &&
               !entry.isNullAware) {
             replacement = new MapEntry(
-                inferrer.helper.buildProblem(messageNonNullAwareSpreadIsNull,
-                    entry.expression.fileOffset, 1),
+                inferrer.helper.buildProblem(
+                    templateNonNullAwareSpreadIsNull.withArguments(
+                        spreadType, inferrer.isNonNullableByDefault),
+                    entry.expression.fileOffset,
+                    1),
                 new NullLiteral())
               ..fileOffset = entry.fileOffset;
           } else if (actualElementType != null) {
diff --git a/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart b/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart
index d6682d401b5..e7f565a5c7f 100644
--- a/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart
@@ -154,9 +154,8 @@ class TypeLabeler implements DartTypeVisitor<void>, ConstantVisitor<void> {
   }
 
   void visitNeverType(NeverType node) {
-    // TODO(askesc): Consider throwing internal error if NeverType appears in
-    //  diagnostics.
     result.add("Never");
+    addNullability(node.declaredNullability);
   }
 
   void visitDynamicType(DynamicType node) {
diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
index 3966bbe4f5f..356c1be8b9b 100644
--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@@ -3914,7 +3914,7 @@ SpreadMapElement:
   severity: CONTEXT
 
 NonNullAwareSpreadIsNull:
-  template: "Can't spread a value with static type Null."
+  template: "Can't spread a value with static type '#type'."
   script: >
     main() {
       <int>[...null];
diff --git a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect
index 48f59522a4d..ae46db2e678 100644
--- a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect
+++ b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect
@@ -76,15 +76,15 @@ library;
 //   Map<String, String> map61 = <String, String>{...mapSpread};
 //                                                   ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type 'Null'.
 //   List<int> lhs70 = <int>[...null];
 //                              ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type 'Null'.
 //   Set<int> set70 = <int>{...null};
 //                             ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:137:8: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:137:8: Error: Can't spread a value with static type 'Null'.
 //     ...null,
 //        ^
 //
@@ -92,7 +92,7 @@ library;
 //     ...null,
 //        ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type 'Null'.
 //   Map<String, int> map70 = <String, int>{...null};
 //                                             ^
 //
@@ -302,10 +302,10 @@ Try providing type arguments for the literal explicitly to disambiguate it.
   core::Map<core::String*, core::String*>* map61 = <core::String*, core::String*>{null: invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:129:51: Error: Can't assign spread entry values of type 'int' to map entry values of type 'String'.
   Map<String, String> map61 = <String, String>{...mapSpread};
                                                   ^"};
-  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type Null.
+  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type 'Null'.
   List<int> lhs70 = <int>[...null];
                              ^"];
-  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final dynamic #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type Null.
+  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final dynamic #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type 'Null'.
   Set<int> set70 = <int>{...null};
                             ^") in #t66;
   core::Set<dynamic>* set71ambiguous = block {
@@ -318,7 +318,7 @@ Try providing type arguments for the literal explicitly to disambiguate it.
       #t68.{core::Set::add}(#t70);
     }
   } =>#t68;
-  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type Null.
+  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type 'Null'.
   Map<String, int> map70 = <String, int>{...null};
                                             ^": null};
   core::List<core::int*>* lhs80 = block {
diff --git a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect
index 91386aeacca..e42c97f8535 100644
--- a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect
@@ -76,15 +76,15 @@ library;
 //   Map<String, String> map61 = <String, String>{...mapSpread};
 //                                                   ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type 'Null'.
 //   List<int> lhs70 = <int>[...null];
 //                              ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type 'Null'.
 //   Set<int> set70 = <int>{...null};
 //                             ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:137:8: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:137:8: Error: Can't spread a value with static type 'Null'.
 //     ...null,
 //        ^
 //
@@ -92,7 +92,7 @@ library;
 //     ...null,
 //        ^
 //
-// pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type 'Null'.
 //   Map<String, int> map70 = <String, int>{...null};
 //                                             ^
 //
@@ -431,10 +431,10 @@ Try providing type arguments for the literal explicitly to disambiguate it.
   core::Map<core::String*, core::String*>* map61 = <core::String*, core::String*>{null: invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:129:51: Error: Can't assign spread entry values of type 'int' to map entry values of type 'String'.
   Map<String, String> map61 = <String, String>{...mapSpread};
                                                   ^"};
-  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type Null.
+  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:131:30: Error: Can't spread a value with static type 'Null'.
   List<int> lhs70 = <int>[...null];
                              ^"];
-  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final core::bool #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type Null.
+  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final core::bool #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:133:29: Error: Can't spread a value with static type 'Null'.
   Set<int> set70 = <int>{...null};
                             ^") in #t66;
   core::Set<dynamic>* set71ambiguous = block {
@@ -453,7 +453,7 @@ Try providing type arguments for the literal explicitly to disambiguate it.
       }
     }
   } =>#t68;
-  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type Null.
+  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general/spread_collection_inference.dart:142:45: Error: Can't spread a value with static type 'Null'.
   Map<String, int> map70 = <String, int>{...null};
                                             ^": null};
   core::List<core::int*>* lhs80 = block {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect
index 5ff354628e7..977c606a02a 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect
@@ -76,15 +76,15 @@ library;
 //   Map<String, String> map61 = <String, String>{...mapSpread};
 //                                                   ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type 'Null'.
 //   List<int> lhs70 = <int>[...null];
 //                              ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type 'Null'.
 //   Set<int> set70 = <int>{...null};
 //                             ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:139:8: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:139:8: Error: Can't spread a value with static type 'Null'.
 //     ...null,
 //        ^
 //
@@ -92,7 +92,7 @@ library;
 //     ...null,
 //        ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type 'Null'.
 //   Map<String, int> map70 = <String, int>{...null};
 //                                             ^
 //
@@ -302,10 +302,10 @@ Try providing type arguments for the literal explicitly to disambiguate it.
   core::Map<core::String*, core::String*>* map61 = <core::String*, core::String*>{null: invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:131:51: Error: Can't assign spread entry values of type 'int' to map entry values of type 'String'.
   Map<String, String> map61 = <String, String>{...mapSpread};
                                                   ^"};
-  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type Null.
+  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type 'Null'.
   List<int> lhs70 = <int>[...null];
                              ^"];
-  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final dynamic #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type Null.
+  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final dynamic #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type 'Null'.
   Set<int> set70 = <int>{...null};
                             ^") in #t66;
   core::Set<dynamic>* set71ambiguous = block {
@@ -318,7 +318,7 @@ Try providing type arguments for the literal explicitly to disambiguate it.
       #t68.{core::Set::add}(#t70);
     }
   } =>#t68;
-  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type Null.
+  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type 'Null'.
   Map<String, int> map70 = <String, int>{...null};
                                             ^": null};
   core::List<core::int*>* lhs80 = block {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect
index 69e0bad73e8..6e97878c64c 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect
@@ -76,15 +76,15 @@ library;
 //   Map<String, String> map61 = <String, String>{...mapSpread};
 //                                                   ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type 'Null'.
 //   List<int> lhs70 = <int>[...null];
 //                              ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type 'Null'.
 //   Set<int> set70 = <int>{...null};
 //                             ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:139:8: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:139:8: Error: Can't spread a value with static type 'Null'.
 //     ...null,
 //        ^
 //
@@ -92,7 +92,7 @@ library;
 //     ...null,
 //        ^
 //
-// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type Null.
+// pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type 'Null'.
 //   Map<String, int> map70 = <String, int>{...null};
 //                                             ^
 //
@@ -431,10 +431,10 @@ Try providing type arguments for the literal explicitly to disambiguate it.
   core::Map<core::String*, core::String*>* map61 = <core::String*, core::String*>{null: invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:131:51: Error: Can't assign spread entry values of type 'int' to map entry values of type 'String'.
   Map<String, String> map61 = <String, String>{...mapSpread};
                                                   ^"};
-  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type Null.
+  core::List<core::int*>* lhs70 = <core::int*>[invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:133:30: Error: Can't spread a value with static type 'Null'.
   List<int> lhs70 = <int>[...null];
                              ^"];
-  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final core::bool #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type Null.
+  core::Set<core::int*>* set70 = let final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>() in let final core::bool #t67 = #t66.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:135:29: Error: Can't spread a value with static type 'Null'.
   Set<int> set70 = <int>{...null};
                             ^") in #t66;
   core::Set<dynamic>* set71ambiguous = block {
@@ -453,7 +453,7 @@ Try providing type arguments for the literal explicitly to disambiguate it.
       }
     }
   } =>#t68;
-  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type Null.
+  core::Map<core::String*, core::int*>* map70 = <core::String*, core::int*>{invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart:144:45: Error: Can't spread a value with static type 'Null'.
   Map<String, int> map70 = <String, int>{...null};
                                             ^": null};
   core::List<core::int*>* lhs80 = block {
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart b/pkg/front_end/testcases/nnbd/issue42758.dart
new file mode 100644
index 00000000000..38474ee5770
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart
@@ -0,0 +1,48 @@
+// Copyright (c) 2020, 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.
+
+test1(Never n1, Never? n2, Null n3) {
+  var l1 = [...n1];
+  var l2 = [...?n1];
+  var l3 = [...n2];
+  var l4 = [...?n2];
+  var l5 = [...n3];
+  var l6 = [...?n3];
+  var s1 = {...n1, n1};
+  var s2 = {...?n1, n1};
+  var s3 = {...n2, n1};
+  var s4 = {...?n2, n1};
+  var s5 = {...n3, n1};
+  var s6 = {...?n3, n1};
+  var m1 = {...n1, n1: n1};
+  var m2 = {...?n1, n1: n1};
+  var m3 = {...n2, n1: n1};
+  var m4 = {...?n2, n1: n1};
+  var m5 = {...n3, n1: n1};
+  var m6 = {...?n3, n1: n1};
+}
+
+test2<N1 extends Never, N2 extends Never?, N3 extends Null>(
+    N1 n1, N2 n2, N3 n3) {
+  var l1 = [...n1];
+  var l2 = [...?n1];
+  var l3 = [...n2];
+  var l4 = [...?n2];
+  var l5 = [...n3];
+  var l6 = [...?n3];
+  var s1 = {...n1, n1};
+  var s2 = {...?n1, n1};
+  var s3 = {...n2, n1};
+  var s4 = {...?n2, n1};
+  var s5 = {...n3, n1};
+  var s6 = {...?n3, n1};
+  var m1 = {...n1, n1: n1};
+  var m2 = {...?n1, n1: n1};
+  var m3 = {...n2, n1: n1};
+  var m4 = {...?n2, n1: n1};
+  var m5 = {...n3, n1: n1};
+  var m6 = {...?n3, n1: n1};
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.outline.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.outline.expect
new file mode 100644
index 00000000000..3ada4d69631
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.outline.expect
@@ -0,0 +1,10 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method test1(Never n1, Never? n2, core::Null? n3) → dynamic
+  ;
+static method test2<N1 extends Never = Never, N2 extends Never? = Never?, N3 extends core::Null? = core::Null?>(self::test2::N1 n1, self::test2::N2% n2, self::test2::N3% n3) → dynamic
+  ;
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.strong.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.strong.expect
new file mode 100644
index 00000000000..6e4b63d00b6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.strong.expect
@@ -0,0 +1,293 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:7:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:13:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:19:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:29:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:35:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:41:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+
+static method test1(Never n1, Never? n2, core::Null? n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t1 = <Never>[];
+    for (final Never #t2 in n1)
+      #t1.{core::List::add}(#t2);
+  } =>#t1;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t3 = <Never>[];
+    final core::Iterable<Never>? #t4 = n1;
+    if(!#t4.{core::Object::==}(null))
+      for (final Never #t5 in #t4{core::Iterable<Never>})
+        #t3.{core::List::add}(#t5);
+  } =>#t3;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t6 = <Never>[];
+    final core::Iterable<Never>? #t7 = n2;
+    if(!#t7.{core::Object::==}(null))
+      for (final Never #t8 in #t7{core::Iterable<Never>})
+        #t6.{core::List::add}(#t8);
+  } =>#t6;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t9 = <Never>[];
+    final core::Iterable<Never>? #t10 = n3;
+    if(!#t10.{core::Object::==}(null))
+      for (final Never #t11 in #t10{core::Iterable<Never>})
+        #t9.{core::List::add}(#t11);
+  } =>#t9;
+  core::Set<Never> s1 = block {
+    final core::Set<Never> #t12 = col::LinkedHashSet::•<Never>();
+    for (final Never #t13 in n1)
+      #t12.{core::Set::add}(#t13);
+    #t12.{core::Set::add}(n1);
+  } =>#t12;
+  core::Set<Never> s2 = block {
+    final core::Set<Never> #t14 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t15 = n1;
+    if(!#t15.{core::Object::==}(null))
+      for (final Never #t16 in #t15{core::Iterable<Never>})
+        #t14.{core::Set::add}(#t16);
+    #t14.{core::Set::add}(n1);
+  } =>#t14;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t17 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t18 = #t17.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+  var s3 = {...n2, n1};
+               ^") in let final dynamic #t19 = #t17.{core::Set::add}(n1) in #t17;
+  core::Set<Never> s4 = block {
+    final core::Set<Never> #t20 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t21 = n2;
+    if(!#t21.{core::Object::==}(null))
+      for (final Never #t22 in #t21{core::Iterable<Never>})
+        #t20.{core::Set::add}(#t22);
+    #t20.{core::Set::add}(n1);
+  } =>#t20;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t23 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t24 = #t23.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+  var s5 = {...n3, n1};
+               ^") in let final dynamic #t25 = #t23.{core::Set::add}(n1) in #t23;
+  core::Set<Never> s6 = block {
+    final core::Set<Never> #t26 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t27 = n3;
+    if(!#t27.{core::Object::==}(null))
+      for (final Never #t28 in #t27{core::Iterable<Never>})
+        #t26.{core::Set::add}(#t28);
+    #t26.{core::Set::add}(n1);
+  } =>#t26;
+  core::Map<Never, Never> m1 = block {
+    final core::Map<Never, Never> #t29 = <Never, Never>{};
+    for (final core::MapEntry<Never, Never> #t30 in n1.{core::Map::entries})
+      #t29.{core::Map::[]=}(#t30.{core::MapEntry::key}, #t30.{core::MapEntry::value});
+    #t29.{core::Map::[]=}(n1, n1);
+  } =>#t29;
+  core::Map<Never, Never> m2 = block {
+    final core::Map<Never, Never> #t31 = <Never, Never>{};
+    final core::Map<Never, Never>? #t32 = n1;
+    if(!#t32.{core::Object::==}(null))
+      for (final core::MapEntry<Never, Never> #t33 in #t32{core::Map<Never, Never>}.{core::Map::entries})
+        #t31.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
+    #t31.{core::Map::[]=}(n1, n1);
+  } =>#t31;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m4 = block {
+    final core::Map<Never, Never> #t34 = <Never, Never>{};
+    final core::Map<Never, Never>? #t35 = n2;
+    if(!#t35.{core::Object::==}(null))
+      for (final core::MapEntry<Never, Never> #t36 in #t35{core::Map<Never, Never>}.{core::Map::entries})
+        #t34.{core::Map::[]=}(#t36.{core::MapEntry::key}, #t36.{core::MapEntry::value});
+    #t34.{core::Map::[]=}(n1, n1);
+  } =>#t34;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m6 = block {
+    final core::Map<Never, Never> #t37 = <Never, Never>{};
+    final core::Map<Never, Never>? #t38 = n3;
+    if(!#t38.{core::Object::==}(null))
+      for (final core::MapEntry<Never, Never> #t39 in #t38{core::Map<Never, Never>}.{core::Map::entries})
+        #t37.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
+    #t37.{core::Map::[]=}(n1, n1);
+  } =>#t37;
+}
+static method test2<N1 extends Never = Never, N2 extends Never? = Never?, N3 extends core::Null? = core::Null?>(self::test2::N1 n1, self::test2::N2% n2, self::test2::N3% n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t40 = <Never>[];
+    for (final Never #t41 in n1)
+      #t40.{core::List::add}(#t41);
+  } =>#t40;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t42 = <Never>[];
+    final core::Iterable<Never>? #t43 = n1;
+    if(!#t43.{core::Object::==}(null))
+      for (final Never #t44 in #t43{core::Iterable<Never>})
+        #t42.{core::List::add}(#t44);
+  } =>#t42;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t45 = <Never>[];
+    final core::Iterable<Never>? #t46 = n2;
+    if(!#t46.{core::Object::==}(null))
+      for (final Never #t47 in #t46{core::Iterable<Never>})
+        #t45.{core::List::add}(#t47);
+  } =>#t45;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t48 = <Never>[];
+    final core::Iterable<Never>? #t49 = n3;
+    if(!#t49.{core::Object::==}(null))
+      for (final Never #t50 in #t49{core::Iterable<Never>})
+        #t48.{core::List::add}(#t50);
+  } =>#t48;
+  core::Set<self::test2::N1> s1 = block {
+    final core::Set<self::test2::N1> #t51 = col::LinkedHashSet::•<self::test2::N1>();
+    for (final self::test2::N1 #t52 in n1)
+      #t51.{core::Set::add}(#t52);
+    #t51.{core::Set::add}(n1);
+  } =>#t51;
+  core::Set<self::test2::N1> s2 = block {
+    final core::Set<self::test2::N1> #t53 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t54 = n1;
+    if(!#t54.{core::Object::==}(null))
+      for (final self::test2::N1 #t55 in #t54{core::Iterable<self::test2::N1>})
+        #t53.{core::Set::add}(#t55);
+    #t53.{core::Set::add}(n1);
+  } =>#t53;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t56 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t57 = #t56.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+  var s3 = {...n2, n1};
+               ^") in let final dynamic #t58 = #t56.{core::Set::add}(n1) in #t56;
+  core::Set<self::test2::N1> s4 = block {
+    final core::Set<self::test2::N1> #t59 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t60 = n2;
+    if(!#t60.{core::Object::==}(null))
+      for (final self::test2::N1 #t61 in #t60{core::Iterable<self::test2::N1>})
+        #t59.{core::Set::add}(#t61);
+    #t59.{core::Set::add}(n1);
+  } =>#t59;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t62 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t63 = #t62.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+  var s5 = {...n3, n1};
+               ^") in let final dynamic #t64 = #t62.{core::Set::add}(n1) in #t62;
+  core::Set<self::test2::N1> s6 = block {
+    final core::Set<self::test2::N1> #t65 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t66 = n3;
+    if(!#t66.{core::Object::==}(null))
+      for (final self::test2::N1 #t67 in #t66{core::Iterable<self::test2::N1>})
+        #t65.{core::Set::add}(#t67);
+    #t65.{core::Set::add}(n1);
+  } =>#t65;
+  core::Map<self::test2::N1, self::test2::N1> m1 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t68 = <self::test2::N1, self::test2::N1>{};
+    for (final core::MapEntry<self::test2::N1, self::test2::N1> #t69 in n1.{core::Map::entries})
+      #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
+    #t68.{core::Map::[]=}(n1, n1);
+  } =>#t68;
+  core::Map<self::test2::N1, self::test2::N1> m2 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t70 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t71 = n1;
+    if(!#t71.{core::Object::==}(null))
+      for (final core::MapEntry<self::test2::N1, self::test2::N1> #t72 in #t71{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries})
+        #t70.{core::Map::[]=}(#t72.{core::MapEntry::key}, #t72.{core::MapEntry::value});
+    #t70.{core::Map::[]=}(n1, n1);
+  } =>#t70;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m4 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t73 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t74 = n2;
+    if(!#t74.{core::Object::==}(null))
+      for (final core::MapEntry<self::test2::N1, self::test2::N1> #t75 in #t74{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries})
+        #t73.{core::Map::[]=}(#t75.{core::MapEntry::key}, #t75.{core::MapEntry::value});
+    #t73.{core::Map::[]=}(n1, n1);
+  } =>#t73;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m6 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t76 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t77 = n3;
+    if(!#t77.{core::Object::==}(null))
+      for (final core::MapEntry<self::test2::N1, self::test2::N1> #t78 in #t77{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries})
+        #t76.{core::Map::[]=}(#t78.{core::MapEntry::key}, #t78.{core::MapEntry::value});
+    #t76.{core::Map::[]=}(n1, n1);
+  } =>#t76;
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.strong.transformed.expect
new file mode 100644
index 00000000000..f24f3517fc6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.strong.transformed.expect
@@ -0,0 +1,375 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:7:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:13:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:19:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:29:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:35:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:41:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+
+static method test1(Never n1, Never? n2, core::Null? n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t1 = <Never>[];
+    for (final Never #t2 in n1)
+      #t1.{core::List::add}(#t2);
+  } =>#t1;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t3 = <Never>[];
+    final core::Iterable<Never>? #t4 = n1;
+    if(!#t4.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t4{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t5 = :sync-for-iterator.{core::Iterator::current};
+        #t3.{core::List::add}(#t5);
+      }
+    }
+  } =>#t3;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t6 = <Never>[];
+    final core::Iterable<Never>? #t7 = n2;
+    if(!#t7.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t7{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t8 = :sync-for-iterator.{core::Iterator::current};
+        #t6.{core::List::add}(#t8);
+      }
+    }
+  } =>#t6;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t9 = <Never>[];
+    final core::Iterable<Never>? #t10 = n3;
+    if(!#t10.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t10{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t11 = :sync-for-iterator.{core::Iterator::current};
+        #t9.{core::List::add}(#t11);
+      }
+    }
+  } =>#t9;
+  core::Set<Never> s1 = block {
+    final core::Set<Never> #t12 = col::LinkedHashSet::•<Never>();
+    for (final Never #t13 in n1)
+      #t12.{core::Set::add}(#t13);
+    #t12.{core::Set::add}(n1);
+  } =>#t12;
+  core::Set<Never> s2 = block {
+    final core::Set<Never> #t14 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t15 = n1;
+    if(!#t15.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t15{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t16 = :sync-for-iterator.{core::Iterator::current};
+        #t14.{core::Set::add}(#t16);
+      }
+    }
+    #t14.{core::Set::add}(n1);
+  } =>#t14;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t17 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t18 = #t17.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+  var s3 = {...n2, n1};
+               ^") in let final core::bool #t19 = #t17.{core::Set::add}(n1) in #t17;
+  core::Set<Never> s4 = block {
+    final core::Set<Never> #t20 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t21 = n2;
+    if(!#t21.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t21{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t22 = :sync-for-iterator.{core::Iterator::current};
+        #t20.{core::Set::add}(#t22);
+      }
+    }
+    #t20.{core::Set::add}(n1);
+  } =>#t20;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t23 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t24 = #t23.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+  var s5 = {...n3, n1};
+               ^") in let final core::bool #t25 = #t23.{core::Set::add}(n1) in #t23;
+  core::Set<Never> s6 = block {
+    final core::Set<Never> #t26 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t27 = n3;
+    if(!#t27.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t27{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t28 = :sync-for-iterator.{core::Iterator::current};
+        #t26.{core::Set::add}(#t28);
+      }
+    }
+    #t26.{core::Set::add}(n1);
+  } =>#t26;
+  core::Map<Never, Never> m1 = block {
+    final core::Map<Never, Never> #t29 = <Never, Never>{};
+    {
+      core::Iterator<core::MapEntry<<BottomType>, <BottomType>>> :sync-for-iterator = n1.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t30 = :sync-for-iterator.{core::Iterator::current};
+        #t29.{core::Map::[]=}(#t30.{core::MapEntry::key}, #t30.{core::MapEntry::value});
+      }
+    }
+    #t29.{core::Map::[]=}(n1, n1);
+  } =>#t29;
+  core::Map<Never, Never> m2 = block {
+    final core::Map<Never, Never> #t31 = <Never, Never>{};
+    final core::Map<Never, Never>? #t32 = n1;
+    if(!#t32.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<Never, Never>> :sync-for-iterator = #t32{core::Map<Never, Never>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t33 = :sync-for-iterator.{core::Iterator::current};
+        #t31.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
+      }
+    }
+    #t31.{core::Map::[]=}(n1, n1);
+  } =>#t31;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m4 = block {
+    final core::Map<Never, Never> #t34 = <Never, Never>{};
+    final core::Map<Never, Never>? #t35 = n2;
+    if(!#t35.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<Never, Never>> :sync-for-iterator = #t35{core::Map<Never, Never>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t36 = :sync-for-iterator.{core::Iterator::current};
+        #t34.{core::Map::[]=}(#t36.{core::MapEntry::key}, #t36.{core::MapEntry::value});
+      }
+    }
+    #t34.{core::Map::[]=}(n1, n1);
+  } =>#t34;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m6 = block {
+    final core::Map<Never, Never> #t37 = <Never, Never>{};
+    final core::Map<Never, Never>? #t38 = n3;
+    if(!#t38.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<Never, Never>> :sync-for-iterator = #t38{core::Map<Never, Never>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t39 = :sync-for-iterator.{core::Iterator::current};
+        #t37.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
+      }
+    }
+    #t37.{core::Map::[]=}(n1, n1);
+  } =>#t37;
+}
+static method test2<N1 extends Never = Never, N2 extends Never? = Never?, N3 extends core::Null? = core::Null?>(self::test2::N1 n1, self::test2::N2% n2, self::test2::N3% n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t40 = <Never>[];
+    for (final Never #t41 in n1)
+      #t40.{core::List::add}(#t41);
+  } =>#t40;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t42 = <Never>[];
+    final core::Iterable<Never>? #t43 = n1;
+    if(!#t43.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t43{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t44 = :sync-for-iterator.{core::Iterator::current};
+        #t42.{core::List::add}(#t44);
+      }
+    }
+  } =>#t42;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t45 = <Never>[];
+    final core::Iterable<Never>? #t46 = n2;
+    if(!#t46.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t46{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t47 = :sync-for-iterator.{core::Iterator::current};
+        #t45.{core::List::add}(#t47);
+      }
+    }
+  } =>#t45;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t48 = <Never>[];
+    final core::Iterable<Never>? #t49 = n3;
+    if(!#t49.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t49{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t50 = :sync-for-iterator.{core::Iterator::current};
+        #t48.{core::List::add}(#t50);
+      }
+    }
+  } =>#t48;
+  core::Set<self::test2::N1> s1 = block {
+    final core::Set<self::test2::N1> #t51 = col::LinkedHashSet::•<self::test2::N1>();
+    for (final self::test2::N1 #t52 in n1)
+      #t51.{core::Set::add}(#t52);
+    #t51.{core::Set::add}(n1);
+  } =>#t51;
+  core::Set<self::test2::N1> s2 = block {
+    final core::Set<self::test2::N1> #t53 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t54 = n1;
+    if(!#t54.{core::Object::==}(null)) {
+      core::Iterator<self::test2::N1> :sync-for-iterator = #t54{core::Iterable<self::test2::N1>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final self::test2::N1 #t55 = :sync-for-iterator.{core::Iterator::current};
+        #t53.{core::Set::add}(#t55);
+      }
+    }
+    #t53.{core::Set::add}(n1);
+  } =>#t53;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t56 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t57 = #t56.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+  var s3 = {...n2, n1};
+               ^") in let final core::bool #t58 = #t56.{core::Set::add}(n1) in #t56;
+  core::Set<self::test2::N1> s4 = block {
+    final core::Set<self::test2::N1> #t59 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t60 = n2;
+    if(!#t60.{core::Object::==}(null)) {
+      core::Iterator<self::test2::N1> :sync-for-iterator = #t60{core::Iterable<self::test2::N1>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final self::test2::N1 #t61 = :sync-for-iterator.{core::Iterator::current};
+        #t59.{core::Set::add}(#t61);
+      }
+    }
+    #t59.{core::Set::add}(n1);
+  } =>#t59;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t62 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t63 = #t62.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+  var s5 = {...n3, n1};
+               ^") in let final core::bool #t64 = #t62.{core::Set::add}(n1) in #t62;
+  core::Set<self::test2::N1> s6 = block {
+    final core::Set<self::test2::N1> #t65 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t66 = n3;
+    if(!#t66.{core::Object::==}(null)) {
+      core::Iterator<self::test2::N1> :sync-for-iterator = #t66{core::Iterable<self::test2::N1>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final self::test2::N1 #t67 = :sync-for-iterator.{core::Iterator::current};
+        #t65.{core::Set::add}(#t67);
+      }
+    }
+    #t65.{core::Set::add}(n1);
+  } =>#t65;
+  core::Map<self::test2::N1, self::test2::N1> m1 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t68 = <self::test2::N1, self::test2::N1>{};
+    {
+      core::Iterator<core::MapEntry<<BottomType>, <BottomType>>> :sync-for-iterator = n1.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t69 = :sync-for-iterator.{core::Iterator::current};
+        #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
+      }
+    }
+    #t68.{core::Map::[]=}(n1, n1);
+  } =>#t68;
+  core::Map<self::test2::N1, self::test2::N1> m2 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t70 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t71 = n1;
+    if(!#t71.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<self::test2::N1, self::test2::N1>> :sync-for-iterator = #t71{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t72 = :sync-for-iterator.{core::Iterator::current};
+        #t70.{core::Map::[]=}(#t72.{core::MapEntry::key}, #t72.{core::MapEntry::value});
+      }
+    }
+    #t70.{core::Map::[]=}(n1, n1);
+  } =>#t70;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m4 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t73 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t74 = n2;
+    if(!#t74.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<self::test2::N1, self::test2::N1>> :sync-for-iterator = #t74{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t75 = :sync-for-iterator.{core::Iterator::current};
+        #t73.{core::Map::[]=}(#t75.{core::MapEntry::key}, #t75.{core::MapEntry::value});
+      }
+    }
+    #t73.{core::Map::[]=}(n1, n1);
+  } =>#t73;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m6 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t76 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t77 = n3;
+    if(!#t77.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<self::test2::N1, self::test2::N1>> :sync-for-iterator = #t77{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t78 = :sync-for-iterator.{core::Iterator::current};
+        #t76.{core::Map::[]=}(#t78.{core::MapEntry::key}, #t78.{core::MapEntry::value});
+      }
+    }
+    #t76.{core::Map::[]=}(n1, n1);
+  } =>#t76;
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.textual_outline.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.textual_outline.expect
new file mode 100644
index 00000000000..09008cc5ff0
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.textual_outline.expect
@@ -0,0 +1,4 @@
+test1(Never n1, Never? n2, Null n3) {}
+test2<N1 extends Never, N2 extends Never?, N3 extends Null>(
+    N1 n1, N2 n2, N3 n3) {}
+main() {}
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.textual_outline_modelled.expect
new file mode 100644
index 00000000000..7dc1872078a
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.textual_outline_modelled.expect
@@ -0,0 +1,4 @@
+main() {}
+test1(Never n1, Never? n2, Null n3) {}
+test2<N1 extends Never, N2 extends Never?, N3 extends Null>(
+    N1 n1, N2 n2, N3 n3) {}
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.weak.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.weak.expect
new file mode 100644
index 00000000000..6e4b63d00b6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.weak.expect
@@ -0,0 +1,293 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:7:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:13:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:19:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:29:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:35:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:41:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+
+static method test1(Never n1, Never? n2, core::Null? n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t1 = <Never>[];
+    for (final Never #t2 in n1)
+      #t1.{core::List::add}(#t2);
+  } =>#t1;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t3 = <Never>[];
+    final core::Iterable<Never>? #t4 = n1;
+    if(!#t4.{core::Object::==}(null))
+      for (final Never #t5 in #t4{core::Iterable<Never>})
+        #t3.{core::List::add}(#t5);
+  } =>#t3;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t6 = <Never>[];
+    final core::Iterable<Never>? #t7 = n2;
+    if(!#t7.{core::Object::==}(null))
+      for (final Never #t8 in #t7{core::Iterable<Never>})
+        #t6.{core::List::add}(#t8);
+  } =>#t6;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t9 = <Never>[];
+    final core::Iterable<Never>? #t10 = n3;
+    if(!#t10.{core::Object::==}(null))
+      for (final Never #t11 in #t10{core::Iterable<Never>})
+        #t9.{core::List::add}(#t11);
+  } =>#t9;
+  core::Set<Never> s1 = block {
+    final core::Set<Never> #t12 = col::LinkedHashSet::•<Never>();
+    for (final Never #t13 in n1)
+      #t12.{core::Set::add}(#t13);
+    #t12.{core::Set::add}(n1);
+  } =>#t12;
+  core::Set<Never> s2 = block {
+    final core::Set<Never> #t14 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t15 = n1;
+    if(!#t15.{core::Object::==}(null))
+      for (final Never #t16 in #t15{core::Iterable<Never>})
+        #t14.{core::Set::add}(#t16);
+    #t14.{core::Set::add}(n1);
+  } =>#t14;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t17 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t18 = #t17.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+  var s3 = {...n2, n1};
+               ^") in let final dynamic #t19 = #t17.{core::Set::add}(n1) in #t17;
+  core::Set<Never> s4 = block {
+    final core::Set<Never> #t20 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t21 = n2;
+    if(!#t21.{core::Object::==}(null))
+      for (final Never #t22 in #t21{core::Iterable<Never>})
+        #t20.{core::Set::add}(#t22);
+    #t20.{core::Set::add}(n1);
+  } =>#t20;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t23 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t24 = #t23.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+  var s5 = {...n3, n1};
+               ^") in let final dynamic #t25 = #t23.{core::Set::add}(n1) in #t23;
+  core::Set<Never> s6 = block {
+    final core::Set<Never> #t26 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t27 = n3;
+    if(!#t27.{core::Object::==}(null))
+      for (final Never #t28 in #t27{core::Iterable<Never>})
+        #t26.{core::Set::add}(#t28);
+    #t26.{core::Set::add}(n1);
+  } =>#t26;
+  core::Map<Never, Never> m1 = block {
+    final core::Map<Never, Never> #t29 = <Never, Never>{};
+    for (final core::MapEntry<Never, Never> #t30 in n1.{core::Map::entries})
+      #t29.{core::Map::[]=}(#t30.{core::MapEntry::key}, #t30.{core::MapEntry::value});
+    #t29.{core::Map::[]=}(n1, n1);
+  } =>#t29;
+  core::Map<Never, Never> m2 = block {
+    final core::Map<Never, Never> #t31 = <Never, Never>{};
+    final core::Map<Never, Never>? #t32 = n1;
+    if(!#t32.{core::Object::==}(null))
+      for (final core::MapEntry<Never, Never> #t33 in #t32{core::Map<Never, Never>}.{core::Map::entries})
+        #t31.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
+    #t31.{core::Map::[]=}(n1, n1);
+  } =>#t31;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m4 = block {
+    final core::Map<Never, Never> #t34 = <Never, Never>{};
+    final core::Map<Never, Never>? #t35 = n2;
+    if(!#t35.{core::Object::==}(null))
+      for (final core::MapEntry<Never, Never> #t36 in #t35{core::Map<Never, Never>}.{core::Map::entries})
+        #t34.{core::Map::[]=}(#t36.{core::MapEntry::key}, #t36.{core::MapEntry::value});
+    #t34.{core::Map::[]=}(n1, n1);
+  } =>#t34;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m6 = block {
+    final core::Map<Never, Never> #t37 = <Never, Never>{};
+    final core::Map<Never, Never>? #t38 = n3;
+    if(!#t38.{core::Object::==}(null))
+      for (final core::MapEntry<Never, Never> #t39 in #t38{core::Map<Never, Never>}.{core::Map::entries})
+        #t37.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
+    #t37.{core::Map::[]=}(n1, n1);
+  } =>#t37;
+}
+static method test2<N1 extends Never = Never, N2 extends Never? = Never?, N3 extends core::Null? = core::Null?>(self::test2::N1 n1, self::test2::N2% n2, self::test2::N3% n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t40 = <Never>[];
+    for (final Never #t41 in n1)
+      #t40.{core::List::add}(#t41);
+  } =>#t40;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t42 = <Never>[];
+    final core::Iterable<Never>? #t43 = n1;
+    if(!#t43.{core::Object::==}(null))
+      for (final Never #t44 in #t43{core::Iterable<Never>})
+        #t42.{core::List::add}(#t44);
+  } =>#t42;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t45 = <Never>[];
+    final core::Iterable<Never>? #t46 = n2;
+    if(!#t46.{core::Object::==}(null))
+      for (final Never #t47 in #t46{core::Iterable<Never>})
+        #t45.{core::List::add}(#t47);
+  } =>#t45;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t48 = <Never>[];
+    final core::Iterable<Never>? #t49 = n3;
+    if(!#t49.{core::Object::==}(null))
+      for (final Never #t50 in #t49{core::Iterable<Never>})
+        #t48.{core::List::add}(#t50);
+  } =>#t48;
+  core::Set<self::test2::N1> s1 = block {
+    final core::Set<self::test2::N1> #t51 = col::LinkedHashSet::•<self::test2::N1>();
+    for (final self::test2::N1 #t52 in n1)
+      #t51.{core::Set::add}(#t52);
+    #t51.{core::Set::add}(n1);
+  } =>#t51;
+  core::Set<self::test2::N1> s2 = block {
+    final core::Set<self::test2::N1> #t53 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t54 = n1;
+    if(!#t54.{core::Object::==}(null))
+      for (final self::test2::N1 #t55 in #t54{core::Iterable<self::test2::N1>})
+        #t53.{core::Set::add}(#t55);
+    #t53.{core::Set::add}(n1);
+  } =>#t53;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t56 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t57 = #t56.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+  var s3 = {...n2, n1};
+               ^") in let final dynamic #t58 = #t56.{core::Set::add}(n1) in #t56;
+  core::Set<self::test2::N1> s4 = block {
+    final core::Set<self::test2::N1> #t59 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t60 = n2;
+    if(!#t60.{core::Object::==}(null))
+      for (final self::test2::N1 #t61 in #t60{core::Iterable<self::test2::N1>})
+        #t59.{core::Set::add}(#t61);
+    #t59.{core::Set::add}(n1);
+  } =>#t59;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t62 = col::LinkedHashSet::•<dynamic>() in let final dynamic #t63 = #t62.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+  var s5 = {...n3, n1};
+               ^") in let final dynamic #t64 = #t62.{core::Set::add}(n1) in #t62;
+  core::Set<self::test2::N1> s6 = block {
+    final core::Set<self::test2::N1> #t65 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t66 = n3;
+    if(!#t66.{core::Object::==}(null))
+      for (final self::test2::N1 #t67 in #t66{core::Iterable<self::test2::N1>})
+        #t65.{core::Set::add}(#t67);
+    #t65.{core::Set::add}(n1);
+  } =>#t65;
+  core::Map<self::test2::N1, self::test2::N1> m1 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t68 = <self::test2::N1, self::test2::N1>{};
+    for (final core::MapEntry<self::test2::N1, self::test2::N1> #t69 in n1.{core::Map::entries})
+      #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
+    #t68.{core::Map::[]=}(n1, n1);
+  } =>#t68;
+  core::Map<self::test2::N1, self::test2::N1> m2 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t70 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t71 = n1;
+    if(!#t71.{core::Object::==}(null))
+      for (final core::MapEntry<self::test2::N1, self::test2::N1> #t72 in #t71{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries})
+        #t70.{core::Map::[]=}(#t72.{core::MapEntry::key}, #t72.{core::MapEntry::value});
+    #t70.{core::Map::[]=}(n1, n1);
+  } =>#t70;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m4 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t73 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t74 = n2;
+    if(!#t74.{core::Object::==}(null))
+      for (final core::MapEntry<self::test2::N1, self::test2::N1> #t75 in #t74{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries})
+        #t73.{core::Map::[]=}(#t75.{core::MapEntry::key}, #t75.{core::MapEntry::value});
+    #t73.{core::Map::[]=}(n1, n1);
+  } =>#t73;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m6 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t76 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t77 = n3;
+    if(!#t77.{core::Object::==}(null))
+      for (final core::MapEntry<self::test2::N1, self::test2::N1> #t78 in #t77{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries})
+        #t76.{core::Map::[]=}(#t78.{core::MapEntry::key}, #t78.{core::MapEntry::value});
+    #t76.{core::Map::[]=}(n1, n1);
+  } =>#t76;
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/issue42758.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/issue42758.dart.weak.transformed.expect
new file mode 100644
index 00000000000..f24f3517fc6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/issue42758.dart.weak.transformed.expect
@@ -0,0 +1,375 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:7:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:13:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:19:17: Warning: Operand of null-aware operation '...?' has type 'Never' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:29:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var l2 = [...?n1];
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+//   var l3 = [...n2];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+//   var l5 = [...n3];
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:35:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var s2 = {...?n1, n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+//   var s3 = {...n2, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+//   var s5 = {...n3, n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:41:17: Warning: Operand of null-aware operation '...?' has type 'N1' which excludes null.
+//   var m2 = {...?n1, n1: n1};
+//                 ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+//   var m3 = {...n2, n1: n1};
+//                ^
+//
+// pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+//   var m5 = {...n3, n1: n1};
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+
+static method test1(Never n1, Never? n2, core::Null? n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t1 = <Never>[];
+    for (final Never #t2 in n1)
+      #t1.{core::List::add}(#t2);
+  } =>#t1;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t3 = <Never>[];
+    final core::Iterable<Never>? #t4 = n1;
+    if(!#t4.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t4{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t5 = :sync-for-iterator.{core::Iterator::current};
+        #t3.{core::List::add}(#t5);
+      }
+    }
+  } =>#t3;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:8:16: Error: Can't spread a value with static type 'Never?'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t6 = <Never>[];
+    final core::Iterable<Never>? #t7 = n2;
+    if(!#t7.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t7{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t8 = :sync-for-iterator.{core::Iterator::current};
+        #t6.{core::List::add}(#t8);
+      }
+    }
+  } =>#t6;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:10:16: Error: Can't spread a value with static type 'Null'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t9 = <Never>[];
+    final core::Iterable<Never>? #t10 = n3;
+    if(!#t10.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t10{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t11 = :sync-for-iterator.{core::Iterator::current};
+        #t9.{core::List::add}(#t11);
+      }
+    }
+  } =>#t9;
+  core::Set<Never> s1 = block {
+    final core::Set<Never> #t12 = col::LinkedHashSet::•<Never>();
+    for (final Never #t13 in n1)
+      #t12.{core::Set::add}(#t13);
+    #t12.{core::Set::add}(n1);
+  } =>#t12;
+  core::Set<Never> s2 = block {
+    final core::Set<Never> #t14 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t15 = n1;
+    if(!#t15.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t15{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t16 = :sync-for-iterator.{core::Iterator::current};
+        #t14.{core::Set::add}(#t16);
+      }
+    }
+    #t14.{core::Set::add}(n1);
+  } =>#t14;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t17 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t18 = #t17.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:14:16: Error: Can't spread a value with static type 'Never?'.
+  var s3 = {...n2, n1};
+               ^") in let final core::bool #t19 = #t17.{core::Set::add}(n1) in #t17;
+  core::Set<Never> s4 = block {
+    final core::Set<Never> #t20 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t21 = n2;
+    if(!#t21.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t21{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t22 = :sync-for-iterator.{core::Iterator::current};
+        #t20.{core::Set::add}(#t22);
+      }
+    }
+    #t20.{core::Set::add}(n1);
+  } =>#t20;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t23 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t24 = #t23.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:16:16: Error: Can't spread a value with static type 'Null'.
+  var s5 = {...n3, n1};
+               ^") in let final core::bool #t25 = #t23.{core::Set::add}(n1) in #t23;
+  core::Set<Never> s6 = block {
+    final core::Set<Never> #t26 = col::LinkedHashSet::•<Never>();
+    final core::Iterable<Never>? #t27 = n3;
+    if(!#t27.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t27{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t28 = :sync-for-iterator.{core::Iterator::current};
+        #t26.{core::Set::add}(#t28);
+      }
+    }
+    #t26.{core::Set::add}(n1);
+  } =>#t26;
+  core::Map<Never, Never> m1 = block {
+    final core::Map<Never, Never> #t29 = <Never, Never>{};
+    {
+      core::Iterator<core::MapEntry<<BottomType>, <BottomType>>> :sync-for-iterator = n1.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t30 = :sync-for-iterator.{core::Iterator::current};
+        #t29.{core::Map::[]=}(#t30.{core::MapEntry::key}, #t30.{core::MapEntry::value});
+      }
+    }
+    #t29.{core::Map::[]=}(n1, n1);
+  } =>#t29;
+  core::Map<Never, Never> m2 = block {
+    final core::Map<Never, Never> #t31 = <Never, Never>{};
+    final core::Map<Never, Never>? #t32 = n1;
+    if(!#t32.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<Never, Never>> :sync-for-iterator = #t32{core::Map<Never, Never>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t33 = :sync-for-iterator.{core::Iterator::current};
+        #t31.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
+      }
+    }
+    #t31.{core::Map::[]=}(n1, n1);
+  } =>#t31;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:20:16: Error: Can't spread a value with static type 'Never?'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m4 = block {
+    final core::Map<Never, Never> #t34 = <Never, Never>{};
+    final core::Map<Never, Never>? #t35 = n2;
+    if(!#t35.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<Never, Never>> :sync-for-iterator = #t35{core::Map<Never, Never>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t36 = :sync-for-iterator.{core::Iterator::current};
+        #t34.{core::Map::[]=}(#t36.{core::MapEntry::key}, #t36.{core::MapEntry::value});
+      }
+    }
+    #t34.{core::Map::[]=}(n1, n1);
+  } =>#t34;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:22:16: Error: Can't spread a value with static type 'Null'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<Never, Never> m6 = block {
+    final core::Map<Never, Never> #t37 = <Never, Never>{};
+    final core::Map<Never, Never>? #t38 = n3;
+    if(!#t38.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<Never, Never>> :sync-for-iterator = #t38{core::Map<Never, Never>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<Never, Never> #t39 = :sync-for-iterator.{core::Iterator::current};
+        #t37.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
+      }
+    }
+    #t37.{core::Map::[]=}(n1, n1);
+  } =>#t37;
+}
+static method test2<N1 extends Never = Never, N2 extends Never? = Never?, N3 extends core::Null? = core::Null?>(self::test2::N1 n1, self::test2::N2% n2, self::test2::N3% n3) → dynamic {
+  core::List<Never> l1 = block {
+    final core::List<Never> #t40 = <Never>[];
+    for (final Never #t41 in n1)
+      #t40.{core::List::add}(#t41);
+  } =>#t40;
+  core::List<Never> l2 = block {
+    final core::List<Never> #t42 = <Never>[];
+    final core::Iterable<Never>? #t43 = n1;
+    if(!#t43.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t43{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t44 = :sync-for-iterator.{core::Iterator::current};
+        #t42.{core::List::add}(#t44);
+      }
+    }
+  } =>#t42;
+  core::List<dynamic> l3 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:30:16: Error: Can't spread a value with static type 'N2'.
+  var l3 = [...n2];
+               ^"];
+  core::List<Never> l4 = block {
+    final core::List<Never> #t45 = <Never>[];
+    final core::Iterable<Never>? #t46 = n2;
+    if(!#t46.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t46{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t47 = :sync-for-iterator.{core::Iterator::current};
+        #t45.{core::List::add}(#t47);
+      }
+    }
+  } =>#t45;
+  core::List<dynamic> l5 = <dynamic>[invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:32:16: Error: Can't spread a value with static type 'N3'.
+  var l5 = [...n3];
+               ^"];
+  core::List<Never> l6 = block {
+    final core::List<Never> #t48 = <Never>[];
+    final core::Iterable<Never>? #t49 = n3;
+    if(!#t49.{core::Object::==}(null)) {
+      core::Iterator<Never> :sync-for-iterator = #t49{core::Iterable<Never>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final Never #t50 = :sync-for-iterator.{core::Iterator::current};
+        #t48.{core::List::add}(#t50);
+      }
+    }
+  } =>#t48;
+  core::Set<self::test2::N1> s1 = block {
+    final core::Set<self::test2::N1> #t51 = col::LinkedHashSet::•<self::test2::N1>();
+    for (final self::test2::N1 #t52 in n1)
+      #t51.{core::Set::add}(#t52);
+    #t51.{core::Set::add}(n1);
+  } =>#t51;
+  core::Set<self::test2::N1> s2 = block {
+    final core::Set<self::test2::N1> #t53 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t54 = n1;
+    if(!#t54.{core::Object::==}(null)) {
+      core::Iterator<self::test2::N1> :sync-for-iterator = #t54{core::Iterable<self::test2::N1>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final self::test2::N1 #t55 = :sync-for-iterator.{core::Iterator::current};
+        #t53.{core::Set::add}(#t55);
+      }
+    }
+    #t53.{core::Set::add}(n1);
+  } =>#t53;
+  core::Set<dynamic> s3 = let final core::Set<dynamic> #t56 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t57 = #t56.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:36:16: Error: Can't spread a value with static type 'N2'.
+  var s3 = {...n2, n1};
+               ^") in let final core::bool #t58 = #t56.{core::Set::add}(n1) in #t56;
+  core::Set<self::test2::N1> s4 = block {
+    final core::Set<self::test2::N1> #t59 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t60 = n2;
+    if(!#t60.{core::Object::==}(null)) {
+      core::Iterator<self::test2::N1> :sync-for-iterator = #t60{core::Iterable<self::test2::N1>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final self::test2::N1 #t61 = :sync-for-iterator.{core::Iterator::current};
+        #t59.{core::Set::add}(#t61);
+      }
+    }
+    #t59.{core::Set::add}(n1);
+  } =>#t59;
+  core::Set<dynamic> s5 = let final core::Set<dynamic> #t62 = col::LinkedHashSet::•<dynamic>() in let final core::bool #t63 = #t62.{core::Set::add}(invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:38:16: Error: Can't spread a value with static type 'N3'.
+  var s5 = {...n3, n1};
+               ^") in let final core::bool #t64 = #t62.{core::Set::add}(n1) in #t62;
+  core::Set<self::test2::N1> s6 = block {
+    final core::Set<self::test2::N1> #t65 = col::LinkedHashSet::•<self::test2::N1>();
+    final core::Iterable<self::test2::N1>? #t66 = n3;
+    if(!#t66.{core::Object::==}(null)) {
+      core::Iterator<self::test2::N1> :sync-for-iterator = #t66{core::Iterable<self::test2::N1>}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final self::test2::N1 #t67 = :sync-for-iterator.{core::Iterator::current};
+        #t65.{core::Set::add}(#t67);
+      }
+    }
+    #t65.{core::Set::add}(n1);
+  } =>#t65;
+  core::Map<self::test2::N1, self::test2::N1> m1 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t68 = <self::test2::N1, self::test2::N1>{};
+    {
+      core::Iterator<core::MapEntry<<BottomType>, <BottomType>>> :sync-for-iterator = n1.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t69 = :sync-for-iterator.{core::Iterator::current};
+        #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
+      }
+    }
+    #t68.{core::Map::[]=}(n1, n1);
+  } =>#t68;
+  core::Map<self::test2::N1, self::test2::N1> m2 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t70 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t71 = n1;
+    if(!#t71.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<self::test2::N1, self::test2::N1>> :sync-for-iterator = #t71{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t72 = :sync-for-iterator.{core::Iterator::current};
+        #t70.{core::Map::[]=}(#t72.{core::MapEntry::key}, #t72.{core::MapEntry::value});
+      }
+    }
+    #t70.{core::Map::[]=}(n1, n1);
+  } =>#t70;
+  core::Map<dynamic, dynamic> m3 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:42:16: Error: Can't spread a value with static type 'N2'.
+  var m3 = {...n2, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m4 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t73 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t74 = n2;
+    if(!#t74.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<self::test2::N1, self::test2::N1>> :sync-for-iterator = #t74{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t75 = :sync-for-iterator.{core::Iterator::current};
+        #t73.{core::Map::[]=}(#t75.{core::MapEntry::key}, #t75.{core::MapEntry::value});
+      }
+    }
+    #t73.{core::Map::[]=}(n1, n1);
+  } =>#t73;
+  core::Map<dynamic, dynamic> m5 = <dynamic, dynamic>{invalid-expression "pkg/front_end/testcases/nnbd/issue42758.dart:44:16: Error: Can't spread a value with static type 'N3'.
+  var m5 = {...n3, n1: n1};
+               ^": null, n1: n1};
+  core::Map<self::test2::N1, self::test2::N1> m6 = block {
+    final core::Map<self::test2::N1, self::test2::N1> #t76 = <self::test2::N1, self::test2::N1>{};
+    final core::Map<self::test2::N1, self::test2::N1>? #t77 = n3;
+    if(!#t77.{core::Object::==}(null)) {
+      core::Iterator<core::MapEntry<self::test2::N1, self::test2::N1>> :sync-for-iterator = #t77{core::Map<self::test2::N1, self::test2::N1>}.{core::Map::entries}.{core::Iterable::iterator};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+        final core::MapEntry<self::test2::N1, self::test2::N1> #t78 = :sync-for-iterator.{core::Iterator::current};
+        #t76.{core::Map::[]=}(#t78.{core::MapEntry::key}, #t78.{core::MapEntry::value});
+      }
+    }
+    #t76.{core::Map::[]=}(n1, n1);
+  } =>#t76;
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.expect b/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.expect
index 40260d90df1..64f137e92be 100644
--- a/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.expect
@@ -22,42 +22,42 @@ library /*isNonNullableByDefault*/;
 //   x?.[42] = 42; // Warning.
 //   ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'foo'.
 //   y.foo(); // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
 //   y.bar; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
 //   y.baz = 42; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'call'.
 //   y(); // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y++; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y += 1; // Error.
 //     ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]' operator.
 //   y[42]; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]=' operator.
 //   y[42] = 42; // Error.
 //    ^
@@ -87,35 +87,35 @@ static method foo(Never x, Never? y) → dynamic {
   let final Never #t9 = x in #t9.{core::Object::==}(null) ?{core::int?} null : #t9.baz = 42;
   let final Never #t10 = x in #t10.{core::Object::==}(null) ?{core::Null?} null : #t10.[](42);
   let final Never #t11 = x in #t11.{core::Object::==}(null) ?{core::int?} null : #t11.[]=(42, 42);
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'foo'.
   y.foo(); // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
   y.bar; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
   y.baz = 42; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'call'.
   y(); // Error.
    ^";
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y++; // Error.
    ^" as{TypeError,ForDynamic,ForNonNullableByDefault} Never?;
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y += 1; // Error.
     ^" as{TypeError,ForDynamic,ForNonNullableByDefault} Never?;
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]' operator.
   y[42]; // Error.
    ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]=' operator.
   y[42] = 42; // Error.
    ^";
diff --git a/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.transformed.expect
index 1eb7ae340f6..2a5f9c51354 100644
--- a/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/never_receiver.dart.strong.transformed.expect
@@ -22,42 +22,42 @@ library /*isNonNullableByDefault*/;
 //   x?.[42] = 42; // Warning.
 //   ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'foo'.
 //   y.foo(); // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
 //   y.bar; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
 //   y.baz = 42; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'call'.
 //   y(); // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y++; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y += 1; // Error.
 //     ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]' operator.
 //   y[42]; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]=' operator.
 //   y[42] = 42; // Error.
 //    ^
@@ -87,35 +87,35 @@ static method foo(Never x, Never? y) → dynamic {
   let final Never #t9 = x in #t9.{core::Object::==}(null) ?{core::int?} null : #t9.baz = 42;
   let final Never #t10 = x in #t10.{core::Object::==}(null) ?{core::Null?} null : #t10.[](42);
   let final Never #t11 = x in #t11.{core::Object::==}(null) ?{core::int?} null : #t11.[]=(42, 42);
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'foo'.
   y.foo(); // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
   y.bar; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
   y.baz = 42; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'call'.
   y(); // Error.
    ^";
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y++; // Error.
    ^";
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y += 1; // Error.
     ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]' operator.
   y[42]; // Error.
    ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]=' operator.
   y[42] = 42; // Error.
    ^";
diff --git a/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.expect b/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.expect
index 40260d90df1..64f137e92be 100644
--- a/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.expect
@@ -22,42 +22,42 @@ library /*isNonNullableByDefault*/;
 //   x?.[42] = 42; // Warning.
 //   ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'foo'.
 //   y.foo(); // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
 //   y.bar; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
 //   y.baz = 42; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'call'.
 //   y(); // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y++; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y += 1; // Error.
 //     ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]' operator.
 //   y[42]; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]=' operator.
 //   y[42] = 42; // Error.
 //    ^
@@ -87,35 +87,35 @@ static method foo(Never x, Never? y) → dynamic {
   let final Never #t9 = x in #t9.{core::Object::==}(null) ?{core::int?} null : #t9.baz = 42;
   let final Never #t10 = x in #t10.{core::Object::==}(null) ?{core::Null?} null : #t10.[](42);
   let final Never #t11 = x in #t11.{core::Object::==}(null) ?{core::int?} null : #t11.[]=(42, 42);
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'foo'.
   y.foo(); // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
   y.bar; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
   y.baz = 42; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'call'.
   y(); // Error.
    ^";
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y++; // Error.
    ^" as{TypeError,ForDynamic,ForNonNullableByDefault} Never?;
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y += 1; // Error.
     ^" as{TypeError,ForDynamic,ForNonNullableByDefault} Never?;
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]' operator.
   y[42]; // Error.
    ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]=' operator.
   y[42] = 42; // Error.
    ^";
diff --git a/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.transformed.expect
index 1eb7ae340f6..2a5f9c51354 100644
--- a/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/never_receiver.dart.weak.transformed.expect
@@ -22,42 +22,42 @@ library /*isNonNullableByDefault*/;
 //   x?.[42] = 42; // Warning.
 //   ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'foo'.
 //   y.foo(); // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
 //   y.bar; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
 //   y.baz = 42; // Error.
 //     ^^^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 // Try correcting the name to the name of an existing method, or defining a method named 'call'.
 //   y(); // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y++; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '+' operator.
 //   y += 1; // Error.
 //     ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]' operator.
 //   y[42]; // Error.
 //    ^
 //
-// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+// pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 // Try correcting the operator to an existing operator, or defining a '[]=' operator.
 //   y[42] = 42; // Error.
 //    ^
@@ -87,35 +87,35 @@ static method foo(Never x, Never? y) → dynamic {
   let final Never #t9 = x in #t9.{core::Object::==}(null) ?{core::int?} null : #t9.baz = 42;
   let final Never #t10 = x in #t10.{core::Object::==}(null) ?{core::Null?} null : #t10.[](42);
   let final Never #t11 = x in #t11.{core::Object::==}(null) ?{core::int?} null : #t11.[]=(42, 42);
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:30:5: Error: The method 'foo' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'foo'.
   y.foo(); // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:31:5: Error: The getter 'bar' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'bar'.
   y.bar; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:32:5: Error: The setter 'baz' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'baz'.
   y.baz = 42; // Error.
     ^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:33:4: Error: The method 'call' isn't defined for the class 'Never?'.
 Try correcting the name to the name of an existing method, or defining a method named 'call'.
   y(); // Error.
    ^";
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:34:4: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y++; // Error.
    ^";
-  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never'.
+  y = invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:35:5: Error: The operator '+' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '+' operator.
   y += 1; // Error.
     ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:36:4: Error: The operator '[]' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]' operator.
   y[42]; // Error.
    ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never'.
+  invalid-expression "pkg/front_end/testcases/nnbd/never_receiver.dart:37:4: Error: The operator '[]=' isn't defined for the class 'Never?'.
 Try correcting the operator to an existing operator, or defining a '[]=' operator.
   y[42] = 42; // Error.
    ^";
diff --git a/pkg/kernel/lib/ast.dart b/pkg/kernel/lib/ast.dart
index 529bfb44c28..e1bf6e01954 100644
--- a/pkg/kernel/lib/ast.dart
+++ b/pkg/kernel/lib/ast.dart
@@ -3021,6 +3021,9 @@ abstract class Expression extends TreeNode {
     if (type == context.typeEnvironment.nullType) {
       return context.typeEnvironment.coreTypes
           .bottomInterfaceType(superclass, context.nullable);
+    } else if (type is NeverType) {
+      return context.typeEnvironment.coreTypes
+          .bottomInterfaceType(superclass, type.nullability);
     }
     if (type is InterfaceType) {
       List<DartType> upcastTypeArguments = context.typeEnvironment
diff --git a/pkg/kernel/lib/type_checker.dart b/pkg/kernel/lib/type_checker.dart
index 7eeef0cc7d6..5db606b2766 100644
--- a/pkg/kernel/lib/type_checker.dart
+++ b/pkg/kernel/lib/type_checker.dart
@@ -249,7 +249,7 @@ class TypeCheckingVisitor
     while (type is TypeParameterType) {
       type = (type as TypeParameterType).bound;
     }
-    if (type is BottomType) {
+    if (type is BottomType || type is NeverType || type == coreTypes.nullType) {
       // The bottom type is a subtype of all types, so it should be allowed.
       return Substitution.bottomForClass(superclass);
     }