[cfe/ffi] Error on compound constructors

TEST=co19/LibTest/ffi/Struct/Struct_A02_t01
TEST=co19/LibTest/ffi/Union/Union_A03_t01
TEST=co19/LibTest/ffi/Union/Union_A03_t02
TEST=co19/LibTest/ffi/Union/Union_A03_t03
TEST=co19/LibTest/ffi/Union/Union_A04_t01

Closes: https://github.com/dart-lang/sdk/issues/46813
Change-Id: I2a057613a62eccc0de81083a6f63f8ba68430fc9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/293684
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -4643,6 +4643,15 @@ Message _withArgumentsFfiCompoundImplementsFinalizable(
       arguments: {'string': string, 'name': name});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeFfiCreateOfStructOrUnion = messageFfiCreateOfStructOrUnion;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageFfiCreateOfStructOrUnion = const MessageCode(
+    "FfiCreateOfStructOrUnion",
+    problemMessage:
+        r"""Subclasses of 'Struct' and 'Union' are backed by native memory, and can't be instantiated by a generative constructor. Try allocating it via allocation, or load from a 'Pointer'.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
     Message Function(

pkg/front_end/lib/src/api_unstable/vm.dart

@@ -59,6 +59,7 @@ export '../fasta/fasta_codes.dart'
         LocatedMessage,
         messageFfiAbiSpecificIntegerInvalid,
         messageFfiAbiSpecificIntegerMappingInvalid,
+        messageFfiCreateOfStructOrUnion,
         messageFfiExceptionalReturnNull,
         messageFfiExpectedConstant,
         messageFfiLeafCallMustNotReturnHandle,

pkg/front_end/messages.status

@@ -377,6 +377,7 @@ FastaUsageShort/analyzerCode: Fail
 FastaUsageShort/example: Fail
 FfiAbiSpecificIntegerInvalid/analyzerCode: Fail
 FfiAbiSpecificIntegerMappingInvalid/analyzerCode: Fail
+FfiCreateOfStructOrUnion/analyzerCode: Fail
 FfiCompoundImplementsFinalizable/analyzerCode: Fail
 FfiDartTypeMismatch/analyzerCode: Fail
 FfiEmptyStruct/analyzerCode: Fail

pkg/front_end/messages.yaml

@@ -4918,6 +4918,11 @@ FfiAbiSpecificIntegerMappingInvalid:
   problemMessage: "Classes extending 'AbiSpecificInteger' must have exactly one 'AbiSpecificIntegerMapping' annotation specifying the mapping from ABI to a NativeType integer with a fixed size."
   external: test/ffi_test.dart
 
+FfiCreateOfStructOrUnion:
+  # Used by dart:ffi
+  problemMessage: "Subclasses of 'Struct' and 'Union' are backed by native memory, and can't be instantiated by a generative constructor. Try allocating it via allocation, or load from a 'Pointer'."
+  external: test/ffi_test.dart
+
 FfiTypeMismatch:
   # Used by dart:ffi
   problemMessage: "Expected type '#type' to be '#type2', which is the Dart type corresponding to '#type3'."

pkg/front_end/test/spell_checking_list_messages.txt

@@ -22,6 +22,7 @@ augmentation
 augmentations
 augmented
 b
+backed
 c
 cast
 collide

pkg/vm/lib/transformations/ffi/use_sites.dart

@@ -4,6 +4,7 @@
 
 import 'package:front_end/src/api_unstable/vm.dart'
     show
+        messageFfiCreateOfStructOrUnion,
         messageFfiExceptionalReturnNull,
         messageFfiExpectedConstant,
         templateFfiDartTypeMismatch,
@@ -13,6 +14,7 @@ import 'package:front_end/src/api_unstable/vm.dart'
         templateFfiExtendsOrImplementsSealedClass,
         templateFfiNotStatic;
 
+import 'package:front_end/src/api_prototype/lowering_predicates.dart';
 import 'package:kernel/ast.dart';
 import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
 import 'package:kernel/core_types.dart';
@@ -116,17 +118,34 @@ mixin _FfiUseSiteTransformer on FfiTransformer {
     }
   }
 
+  @override
+  visitConstructorInvocation(ConstructorInvocation node) {
+    if (_inFfiTearoff) {
+      return node;
+    }
+    final target = node.target;
+    if (hierarchy.isSubclassOf(target.enclosingClass, compoundClass) &&
+        target.name != Name("#fromTypedDataBase")) {
+      diagnosticReporter.report(messageFfiCreateOfStructOrUnion,
+          node.fileOffset, 1, node.location?.file);
+    }
+    return super.visitConstructorInvocation(node);
+  }
+
   @override
   visitProcedure(Procedure node) {
     assert(_inFfiTearoff == false);
-    _inFfiTearoff = (isFfiLibrary &&
-        node.isExtensionMember &&
-        (node == allocationTearoff ||
-            node == asFunctionTearoff ||
-            node == lookupFunctionTearoff ||
-            node == abiSpecificIntegerPointerElementAtTearoff ||
-            node == structPointerElementAtTearoff ||
-            node == unionPointerElementAtTearoff));
+    _inFfiTearoff = ((isFfiLibrary &&
+            node.isExtensionMember &&
+            (node == allocationTearoff ||
+                node == asFunctionTearoff ||
+                node == lookupFunctionTearoff ||
+                node == abiSpecificIntegerPointerElementAtTearoff ||
+                node == structPointerElementAtTearoff ||
+                node == unionPointerElementAtTearoff))) ||
+        // Dart2wasm uses enabledConstructorTearOffLowerings but these are not
+        // users trying to call constructors.
+        isConstructorTearOffLowering(node);
     final result = super.visitProcedure(node);
     _inFfiTearoff = false;
     return result;