Revert "[cfe/ffi] Improve FFI call mismatched types compile errors"

This reverts commit 206fdf1.

Reason for revert: Flutter issues are caught by this CL, preventing
Flutter from building.
flutter/flutter#108309

Original change's description:
> [cfe/ffi] Improve FFI call mismatched types compile errors
>
> This CL fixes two issues.
>
> 1. `FfiNative`s now check the Dart and native type for compatiblity.
> 2. Both `FfiNative`, `asFunction`, and `lookupFunction` check the type
>    correspondence between native and Dart type with a subtype check of
>    the expected Dart type and the provided Dart type. For functions,
>    any return type is a subtype of a void type. This is fine for Dart,
>    but not for native calls. This CL manually checks the return type
>    for void.
>
> This CL does not fix the inconsistency between `asFunction` and
> `FfiNative` with regard to allowing more strict return types than
> `Object` for `Handle`s
> Issue: #49518
>
> Analyzer fixes in follow up CL.
>
> TEST=tests/ffi/vmspecific_static_checks_ffinative_test.dart
>
> Closes: #49471
> Change-Id: Ibc7bd6a1a0db59cc5fa5d755d76999fd7e9a06a4
> Cq-Include-Trybots: luci.dart.try:analyzer-linux-release-try,analyzer-mac-release-try,vm-ffi-android-debug-arm-try,vm-ffi-android-debug-arm64c-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/252601
> Reviewed-by: Martin Kustermann <[email protected]>
> Commit-Queue: Daco Harkes <[email protected]>

[email protected],[email protected]

Change-Id: Id82b129d491adcc94cdd685a0a0f6a43248c71f2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Issue: #49518
Cq-Include-Trybots: luci.dart.try:analyzer-linux-release-try,analyzer-mac-release-try,vm-ffi-android-debug-arm-try,vm-ffi-android-debug-arm64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/252662
Reviewed-by: Daco Harkes <[email protected]>
Commit-Queue: Daco Harkes <[email protected]>
Bot-Commit: Rubber Stamper <[email protected]>

Author: dcharkes

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

@@ -1120,14 +1120,7 @@ class FfiTransformer extends Transformer {
     if (dartType == correspondingDartType) return;
     if (env.isSubtypeOf(correspondingDartType, dartType,
         SubtypeCheckMode.ignoringNullabilities)) {
-      // If subtype, manually check the return type is not void.
-      if (dartType is! FunctionType || correspondingDartType is! FunctionType) {
-        return;
-      } else if ((dartType.returnType is VoidType) ==
-          (correspondingDartType.returnType is VoidType)) {
-        return;
-      }
-      // One of the return types is void, the other isn't, report error.
+      return;
     }
     diagnosticReporter.report(
         templateFfiTypeMismatch.withArguments(dartType, correspondingDartType,

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

@@ -117,10 +117,9 @@ class FfiNativeTransformer extends FfiTransformer {
   // Replaces return type with Object if it is Handle.
   DartType _wrapReturnType(DartType dartReturnType, DartType ffiReturnType) {
     if (env.isSubtypeOf(
-            ffiReturnType,
-            handleClass.getThisType(coreTypes, Nullability.nonNullable),
-            SubtypeCheckMode.ignoringNullabilities) &&
-        dartReturnType is! VoidType) {
+        ffiReturnType,
+        handleClass.getThisType(coreTypes, Nullability.nonNullable),
+        SubtypeCheckMode.ignoringNullabilities)) {
       return objectClass.getThisType(coreTypes, dartReturnType.nullability);
     }
     return dartReturnType;
@@ -412,8 +411,7 @@ class FfiNativeTransformer extends FfiTransformer {
         nativeFunctionClass, Nullability.legacy, [ffiFunctionType]);
     try {
       ensureNativeTypeValid(nativeType, node);
-      ensureNativeTypeToDartType(nativeType, wrappedDartFunctionType, node,
-          allowHandle: true);
+      ensureNativeTypeToDartType(nativeType, wrappedDartFunctionType, node);
       ensureLeafCallDoesNotUseHandles(nativeType, isLeaf, node);
     } on FfiStaticTypeError {
       // It's OK to swallow the exception because the diagnostics issued will

tests/ffi/vmspecific_static_checks_ffinative_test.dart

@@ -37,10 +37,6 @@ class NativeClassy extends NativeFieldWrapperClass1 {
   // Error: Missing receiver in FfiNative annotation.
   @FfiNative<Void Function(IntPtr)>('doesntmatter') //# 05: compile-time error
   external void badMissingReceiver(int v); //# 05: compile-time error
-
-  // Error: wrong return type.
-  @FfiNative<Handle Function(Pointer<Void>, Uint32, Uint32, Handle)>('doesntmatter') //# 49471: compile-time error
-  external void toImageSync(int width, int height, Object outImage);  //# 49471: compile-time error
 }
 
 // Error: Too many FfiNative parameters.

tests/ffi/vmspecific_static_checks_test.dart

@@ -64,7 +64,6 @@ void main() {
   testAsFunctionTakesHandle();
   testLookupFunctionReturnsHandle();
   testAsFunctionReturnsHandle();
-  testReturnVoidNotVoid();
 }
 
 typedef Int8UnOp = Int8 Function(Int8);
@@ -821,11 +820,3 @@ class MyFinalizableStruct extends Struct
 {
   external Pointer<Void> field;
 }
-
-void testReturnVoidNotVoid() {
-  // Taking a more specific argument is okay.
-  testLibrary //# 49471: compile-time error
-      .lookupFunction< //# 49471: compile-time error
-          Handle Function(), //# 49471: compile-time error
-          void Function()>("doesntmatter"); //# 49471: compile-time error
-}