[vm/ffi] Support Unions

Closes: #38491

tools/test.py ffi ffi_2
TEST=tests/ffi(_2)/(.*)by_value_(*.)_test.dart

Change-Id: I6d29f7e3c3046cda4a15c9b42063c66b064787be
Cq-Include-Trybots: luci.dart.try:dart-sdk-linux-try,dart-sdk-mac-try,dart-sdk-win-try,vm-ffi-android-debug-arm-try,vm-ffi-android-debug-arm64-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-mac-debug-x64-try,vm-kernel-linux-debug-ia32-try,vm-kernel-linux-debug-x64-try,vm-kernel-nnbd-linux-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,vm-kernel-nnbd-mac-release-x64-try,vm-kernel-nnbd-win-debug-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-nnbd-linux-debug-x64-try,vm-kernel-precomp-win-release-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-win-debug-x64-try,vm-kernel-win-debug-ia32-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-msan-linux-release-x64-try,vm-kernel-precomp-msan-linux-release-x64-try,vm-kernel-precomp-android-release-arm_x64-try,analyzer-analysis-server-linux-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-linux-debug-x64c-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/194420
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>

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

@@ -3735,26 +3735,30 @@ const MessageCode messageFastaUsageShort =
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
-    Message Function(String name)> templateFfiEmptyStruct = const Template<
-        Message Function(String name)>(
+    Message Function(
+        String string,
+        String
+            name)> templateFfiEmptyStruct = const Template<
+        Message Function(String string, String name)>(
     messageTemplate:
-        r"""Struct '#name' is empty. Empty structs are undefined behavior.""",
+        r"""#string '#name' is empty. Empty structs and unions are undefined behavior.""",
     withArguments: _withArgumentsFfiEmptyStruct);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String name)> codeFfiEmptyStruct =
-    const Code<Message Function(String name)>(
+const Code<Message Function(String string, String name)> codeFfiEmptyStruct =
+    const Code<Message Function(String string, String name)>(
   "FfiEmptyStruct",
 );
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsFfiEmptyStruct(String name) {
+Message _withArgumentsFfiEmptyStruct(String string, String name) {
+  if (string.isEmpty) throw 'No string provided';
   if (name.isEmpty) throw 'No name provided';
   name = demangleMixinApplicationName(name);
   return new Message(codeFfiEmptyStruct,
       message:
-          """Struct '${name}' is empty. Empty structs are undefined behavior.""",
-      arguments: {'name': name});
+          """${string} '${name}' is empty. Empty structs and unions are undefined behavior.""",
+      arguments: {'string': string, 'name': name});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ -3802,7 +3806,7 @@ const Template<
     Message Function(String name)> templateFfiFieldAnnotation = const Template<
         Message Function(String name)>(
     messageTemplate:
-        r"""Field '#name' requires exactly one annotation to declare its native type, which cannot be Void. dart:ffi Structs cannot have regular Dart fields.""",
+        r"""Field '#name' requires exactly one annotation to declare its native type, which cannot be Void. dart:ffi Structs and Unions cannot have regular Dart fields.""",
     withArguments: _withArgumentsFfiFieldAnnotation);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ -3817,33 +3821,36 @@ Message _withArgumentsFfiFieldAnnotation(String name) {
   name = demangleMixinApplicationName(name);
   return new Message(codeFfiFieldAnnotation,
       message:
-          """Field '${name}' requires exactly one annotation to declare its native type, which cannot be Void. dart:ffi Structs cannot have regular Dart fields.""",
+          """Field '${name}' requires exactly one annotation to declare its native type, which cannot be Void. dart:ffi Structs and Unions cannot have regular Dart fields.""",
       arguments: {'name': name});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<Message Function(String name, List<String> _names)>
-    templateFfiFieldCyclic =
-    const Template<Message Function(String name, List<String> _names)>(
-        messageTemplate: r"""Struct '#name' contains itself. Cycle elements:
+const Template<
+        Message Function(String string, String name, List<String> _names)>
+    templateFfiFieldCyclic = const Template<
+            Message Function(String string, String name, List<String> _names)>(
+        messageTemplate: r"""#string '#name' contains itself. Cycle elements:
 #names""", withArguments: _withArgumentsFfiFieldCyclic);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String name, List<String> _names)>
-    codeFfiFieldCyclic =
-    const Code<Message Function(String name, List<String> _names)>(
+const Code<Message Function(String string, String name, List<String> _names)>
+    codeFfiFieldCyclic = const Code<
+        Message Function(String string, String name, List<String> _names)>(
   "FfiFieldCyclic",
 );
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsFfiFieldCyclic(String name, List<String> _names) {
+Message _withArgumentsFfiFieldCyclic(
+    String string, String name, List<String> _names) {
+  if (string.isEmpty) throw 'No string provided';
   if (name.isEmpty) throw 'No name provided';
   name = demangleMixinApplicationName(name);
   if (_names.isEmpty) throw 'No names provided';
   String names = itemizeNames(_names);
   return new Message(codeFfiFieldCyclic,
-      message: """Struct '${name}' contains itself. Cycle elements:
-${names}""", arguments: {'name': name, 'names': _names});
+      message: """${string} '${name}' contains itself. Cycle elements:
+${names}""", arguments: {'string': string, 'name': name, 'names': _names});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ -3904,7 +3911,7 @@ const Template<
     Message Function(String name)> templateFfiFieldNull = const Template<
         Message Function(String name)>(
     messageTemplate:
-        r"""Field '#name' cannot have type 'Null', it must be `int`, `double`, `Pointer`, or a subtype of `Struct`.""",
+        r"""Field '#name' cannot have type 'Null', it must be `int`, `double`, `Pointer`, or a subtype of `Struct` or `Union`.""",
     withArguments: _withArgumentsFfiFieldNull);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ -3919,7 +3926,7 @@ Message _withArgumentsFfiFieldNull(String name) {
   name = demangleMixinApplicationName(name);
   return new Message(codeFfiFieldNull,
       message:
-          """Field '${name}' cannot have type 'Null', it must be `int`, `double`, `Pointer`, or a subtype of `Struct`.""",
+          """Field '${name}' cannot have type 'Null', it must be `int`, `double`, `Pointer`, or a subtype of `Struct` or `Union`.""",
       arguments: {'name': name});
 }
 
@@ -4058,24 +4065,26 @@ Message _withArgumentsFfiSizeAnnotationDimensions(String name) {
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<Message Function(String name)> templateFfiStructGeneric =
-    const Template<Message Function(String name)>(
-        messageTemplate: r"""Struct '#name' should not be generic.""",
+const Template<Message Function(String string, String name)>
+    templateFfiStructGeneric =
+    const Template<Message Function(String string, String name)>(
+        messageTemplate: r"""#string '#name' should not be generic.""",
         withArguments: _withArgumentsFfiStructGeneric);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String name)> codeFfiStructGeneric =
-    const Code<Message Function(String name)>(
+const Code<Message Function(String string, String name)> codeFfiStructGeneric =
+    const Code<Message Function(String string, String name)>(
   "FfiStructGeneric",
 );
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsFfiStructGeneric(String name) {
+Message _withArgumentsFfiStructGeneric(String string, String name) {
+  if (string.isEmpty) throw 'No string provided';
   if (name.isEmpty) throw 'No name provided';
   name = demangleMixinApplicationName(name);
   return new Message(codeFfiStructGeneric,
-      message: """Struct '${name}' should not be generic.""",
-      arguments: {'name': name});
+      message: """${string} '${name}' should not be generic.""",
+      arguments: {'string': string, 'name': name});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.

pkg/front_end/messages.yaml

@@ -4366,7 +4366,7 @@ FfiTypeMismatch:
 
 FfiEmptyStruct:
   # Used by dart:ffi
-  template: "Struct '#name' is empty. Empty structs are undefined behavior."
+  template: "#string '#name' is empty. Empty structs and unions are undefined behavior."
   external: test/ffi_test.dart
 
 FfiTypeInvalid:
@@ -4376,12 +4376,12 @@ FfiTypeInvalid:
 
 FfiFieldNull:
   # Used by dart:ffi
-  template: "Field '#name' cannot have type 'Null', it must be `int`, `double`, `Pointer`, or a subtype of `Struct`."
+  template: "Field '#name' cannot have type 'Null', it must be `int`, `double`, `Pointer`, or a subtype of `Struct` or `Union`."
   external: test/ffi_test.dart
 
 FfiFieldAnnotation:
   # Used by dart:ffi
-  template: "Field '#name' requires exactly one annotation to declare its native type, which cannot be Void. dart:ffi Structs cannot have regular Dart fields."
+  template: "Field '#name' requires exactly one annotation to declare its native type, which cannot be Void. dart:ffi Structs and Unions cannot have regular Dart fields."
   external: test/ffi_test.dart
 
 FfiFieldNoAnnotation:
@@ -4392,7 +4392,7 @@ FfiFieldNoAnnotation:
 FfiFieldCyclic:
   # Used by dart:ffi
   template: |
-    Struct '#name' contains itself. Cycle elements:
+    #string '#name' contains itself. Cycle elements:
     #names
   external: test/ffi_test.dart
 
@@ -4439,7 +4439,7 @@ FfiSizeAnnotationDimensions:
 
 FfiStructGeneric:
   # Used by dart:ffi
-  template: "Struct '#name' should not be generic."
+  template: "#string '#name' should not be generic."
   external: test/ffi_test.dart
 
 FfiDartTypeMismatch:

pkg/front_end/test/spell_checking_list_common.txt

@@ -3181,6 +3181,7 @@ unimplemented
 uninitialized
 union
 unioned
+unions
 unique
 unit
 unite

pkg/front_end/testcases/nnbd/ffi_struct_inline_array.dart.strong.expect

@@ -25,4 +25,4 @@ constants  {
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array.dart.strong.transformed.expect

@@ -48,4 +48,4 @@ constants  {
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array.dart.weak.expect

@@ -25,4 +25,4 @@ constants  {
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array.dart.weak.transformed.expect

@@ -48,4 +48,4 @@ constants  {
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array_multi_dimensional.dart.strong.expect

@@ -33,4 +33,4 @@ constants  {
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array_multi_dimensional.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array_multi_dimensional.dart.strong.transformed.expect

@@ -80,4 +80,4 @@ Extra constant evaluation: evaluated: 110, effectively constant: 2
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array_multi_dimensional.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array_multi_dimensional.dart.weak.expect

@@ -33,4 +33,4 @@ constants  {
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array_multi_dimensional.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/front_end/testcases/nnbd/ffi_struct_inline_array_multi_dimensional.dart.weak.transformed.expect

@@ -80,4 +80,4 @@ Extra constant evaluation: evaluated: 110, effectively constant: 2
 
 Constructor coverage from constants:
 org-dartlang-testcase:///ffi_struct_inline_array_multi_dimensional.dart:
-- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:134:9)
+- _ArraySize. (from org-dartlang-sdk:///sdk/lib/ffi/ffi.dart:135:9)

pkg/vm/lib/transformations/ffi.dart

@@ -231,6 +231,7 @@ class FfiTransformer extends Transformer {
   final Class pointerClass;
   final Class compoundClass;
   final Class structClass;
+  final Class unionClass;
   final Class ffiStructLayoutClass;
   final Field ffiStructLayoutTypesField;
   final Field ffiStructLayoutPackingField;
@@ -247,7 +248,10 @@ class FfiTransformer extends Transformer {
   final Procedure addressGetter;
   final Procedure structPointerRef;
   final Procedure structPointerElemAt;
+  final Procedure unionPointerRef;
+  final Procedure unionPointerElemAt;
   final Procedure structArrayElemAt;
+  final Procedure unionArrayElemAt;
   final Procedure arrayArrayElemAt;
   final Procedure arrayArrayAssignAt;
   final Procedure asFunctionMethod;
@@ -264,6 +268,7 @@ class FfiTransformer extends Transformer {
   final Field arrayNestedDimensionsFirst;
   final Field arrayNestedDimensionsRest;
   final Constructor structFromTypedDataBase;
+  final Constructor unionFromTypedDataBase;
   final Constructor arrayConstructor;
   final Procedure fromAddressInternal;
   final Procedure libraryLookupMethod;
@@ -333,6 +338,7 @@ class FfiTransformer extends Transformer {
         pointerClass = index.getClass('dart:ffi', 'Pointer'),
         compoundClass = index.getClass('dart:ffi', '_Compound'),
         structClass = index.getClass('dart:ffi', 'Struct'),
+        unionClass = index.getClass('dart:ffi', 'Union'),
         ffiStructLayoutClass = index.getClass('dart:ffi', '_FfiStructLayout'),
         ffiStructLayoutTypesField =
             index.getMember('dart:ffi', '_FfiStructLayout', 'fieldTypes'),
@@ -369,14 +375,20 @@ class FfiTransformer extends Transformer {
             index.getMember('dart:ffi', 'Array', '_nestedDimensionsRest'),
         structFromTypedDataBase =
             index.getMember('dart:ffi', 'Struct', '_fromTypedDataBase'),
+        unionFromTypedDataBase =
+            index.getMember('dart:ffi', 'Union', '_fromTypedDataBase'),
         arrayConstructor = index.getMember('dart:ffi', 'Array', '_'),
         fromAddressInternal =
             index.getTopLevelMember('dart:ffi', '_fromAddress'),
         structPointerRef =
             index.getMember('dart:ffi', 'StructPointer', 'get:ref'),
         structPointerElemAt =
             index.getMember('dart:ffi', 'StructPointer', '[]'),
+        unionPointerRef =
+            index.getMember('dart:ffi', 'UnionPointer', 'get:ref'),
+        unionPointerElemAt = index.getMember('dart:ffi', 'UnionPointer', '[]'),
         structArrayElemAt = index.getMember('dart:ffi', 'StructArray', '[]'),
+        unionArrayElemAt = index.getMember('dart:ffi', 'UnionArray', '[]'),
         arrayArrayElemAt = index.getMember('dart:ffi', 'ArrayArray', '[]'),
         arrayArrayAssignAt = index.getMember('dart:ffi', 'ArrayArray', '[]='),
         asFunctionMethod =
@@ -478,7 +490,7 @@ class FfiTransformer extends Transformer {
       return nativeType;
     }
     if (hierarchy.isSubclassOf(nativeClass, compoundClass)) {
-      if (nativeClass == structClass) {
+      if (nativeClass == structClass || nativeClass == unionClass) {
         return null;
       }
       return allowCompounds ? nativeType : null;
@@ -749,11 +761,13 @@ class FfiTransformer extends Transformer {
       return false;
     }
     if (type is InterfaceType) {
-      if (type.classNode == structClass) {
+      if (type.classNode == structClass || type.classNode == unionClass) {
         return false;
       }
     }
-    return env.isSubtypeOf(type, InterfaceType(structClass, Nullability.legacy),
+    return env.isSubtypeOf(
+        type,
+        InterfaceType(compoundClass, Nullability.legacy),
         SubtypeCheckMode.ignoringNullabilities);
   }
 }