[vm/ffi] Change Pointer.elementAt and sizeOf to use static type

This CL changes the semantics of
`Pointer<T extends NativeType>.elementAt` and
`sizeOf<T extends NativeType>` to use the compile-time `T` rather than
the runtime `T`.

Issue: https://github.com/dart-lang/sdk/issues/38721

TEST=tests/ffi/data_test.dart
TEST=tests/ffi/sizeof_test.dart
TEST=tests/ffi/structs_test.dart
TEST=tests/ffi/vmspecific_static_checks_test.dart

Change-Id: Ifb25a4bd66d50a385d3db6dec9213b96dff21722
Cq-Include-Trybots: luci.dart.try:vm-precomp-ffi-qemu-linux-release-arm-try,analyzer-analysis-server-linux-try,analyzer-linux-release-try,analyzer-nnbd-linux-release-try,front-end-linux-release-x64-try,front-end-nnbd-linux-release-x64-try,benchmark-linux-try,dart-sdk-linux-try,pkg-linux-release-try,vm-ffi-android-release-arm-try,vm-ffi-android-release-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/178200
Reviewed-by: Aske Simon Christensen <askesc@google.com>

pkg/analyzer/lib/error/error.dart

@@ -474,7 +474,6 @@ const List<ErrorCode> errorCodeValues = [
   FfiCode.MUST_BE_A_NATIVE_FUNCTION_TYPE,
   FfiCode.MUST_BE_A_SUBTYPE,
   FfiCode.NON_CONSTANT_TYPE_ARGUMENT,
-  FfiCode.NON_CONSTANT_TYPE_ARGUMENT_WARNING,
   FfiCode.NON_NATIVE_FUNCTION_TYPE_ARGUMENT_TO_POINTER,
   FfiCode.NON_SIZED_TYPE_ARGUMENT,
   FfiCode.SUBTYPE_OF_FFI_CLASS_IN_EXTENDS,

pkg/analyzer/lib/src/dart/error/ffi_code.dart

@@ -183,20 +183,6 @@ class FfiCode extends AnalyzerErrorCode {
           "parameters are not constants.",
       correction: "Try changing the type argument to be a constant type.");
 
-  /**
-   * Parameters:
-   * 0: the name of the function, method, or constructor having type arguments
-   */
-  static const FfiCode NON_CONSTANT_TYPE_ARGUMENT_WARNING = FfiCode(
-      name: 'NON_CONSTANT_TYPE_ARGUMENT_WARNING',
-      message:
-          "Support for using non-constant type arguments '{0}' in this FFI API"
-          " is deprecated and will be removed in the next stable version of "
-          "Dart. Rewrite the code to ensure that type arguments are compile "
-          "time constants referring to a valid native type.",
-      correction: "Try changing the type argument to be a constant type.",
-      type: ErrorType.HINT);
-
   /**
    * Parameters:
    * 0: the type that should be a valid dart:ffi native type.

pkg/analyzer/lib/src/generated/ffi_verifier.dart

@@ -525,9 +525,7 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
       if (!_isValidFfiNativeType(T, allowVoid: true, allowEmptyStruct: true)) {
         final AstNode errorNode = node;
         _errorReporter.reportErrorForNode(
-            FfiCode.NON_CONSTANT_TYPE_ARGUMENT_WARNING,
+            FfiCode.NON_CONSTANT_TYPE_ARGUMENT, errorNode, ['elementAt']);
-            errorNode,
-            ['elementAt']);
       }
     }
   }
@@ -703,7 +701,7 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
     if (!_isValidFfiNativeType(T, allowVoid: true, allowEmptyStruct: true)) {
       final AstNode errorNode = node;
       _errorReporter.reportErrorForNode(
-          FfiCode.NON_CONSTANT_TYPE_ARGUMENT_WARNING, errorNode, ['sizeOf']);
+          FfiCode.NON_CONSTANT_TYPE_ARGUMENT, errorNode, ['sizeOf']);
     }
   }
 

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

@@ -62,7 +62,6 @@ export '../fasta/fasta_codes.dart'
         templateFfiFieldCyclic,
         templateFfiFieldInitializer,
         templateFfiFieldNoAnnotation,
-        templateFfiNonConstantTypeArgumentWarning,
         templateFfiNotStatic,
         templateFfiStructGeneric,
         templateFfiTypeInvalid,

pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart

@@ -915,35 +915,6 @@ Message _withArgumentsFfiExpectedNoExceptionalReturn(
       arguments: {'type': _type});
 }
 
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<Message Function(DartType _type, bool isNonNullableByDefault)>
-    templateFfiNonConstantTypeArgumentWarning = const Template<
-            Message Function(DartType _type, bool isNonNullableByDefault)>(
-        messageTemplate:
-            r"""Support for using non-constant type arguments '#type' in this FFI API is deprecated and will be removed in the next stable version of Dart. Rewrite the code to ensure that type arguments are compile time constants referring to a valid native type.""",
-        withArguments: _withArgumentsFfiNonConstantTypeArgumentWarning);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(DartType _type, bool isNonNullableByDefault)>
-    codeFfiNonConstantTypeArgumentWarning =
-    const Code<Message Function(DartType _type, bool isNonNullableByDefault)>(
-        "FfiNonConstantTypeArgumentWarning",
-        analyzerCodes: <String>["NON_CONSTANT_TYPE_ARGUMENT_WARNING"],
-        severity: Severity.info);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsFfiNonConstantTypeArgumentWarning(
-    DartType _type, bool isNonNullableByDefault) {
-  TypeLabeler labeler = new TypeLabeler(isNonNullableByDefault);
-  List<Object> typeParts = labeler.labelType(_type);
-  String type = typeParts.join();
-  return new Message(codeFfiNonConstantTypeArgumentWarning,
-      message:
-          """Support for using non-constant type arguments '${type}' in this FFI API is deprecated and will be removed in the next stable version of Dart. Rewrite the code to ensure that type arguments are compile time constants referring to a valid native type.""" +
-              labeler.originMessages,
-      arguments: {'type': _type});
-}
-
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
     Message Function(

pkg/front_end/messages.yaml

@@ -4242,13 +4242,6 @@ FfiFieldCyclic:
     #names
   external: test/ffi_test.dart
 
-FfiNonConstantTypeArgumentWarning:
-  # Used by dart:ffi
-  template: "Support for using non-constant type arguments '#type' in this FFI API is deprecated and will be removed in the next stable version of Dart. Rewrite the code to ensure that type arguments are compile time constants referring to a valid native type."
-  analyzerCode: NON_CONSTANT_TYPE_ARGUMENT_WARNING
-  severity: INFO
-  external: test/ffi_test.dart
-
 FfiNotStatic:
   # Used by dart:ffi
   template: "#name expects a static function as parameter. dart:ffi only supports calling static Dart functions from native code."

pkg/vm/lib/transformations/ffi_use_sites.dart

@@ -13,7 +13,6 @@ import 'package:front_end/src/api_unstable/vm.dart'
         templateFfiExpectedExceptionalReturn,
         templateFfiExpectedNoExceptionalReturn,
         templateFfiExtendsOrImplementsSealedClass,
-        templateFfiNonConstantTypeArgumentWarning,
         templateFfiNotStatic,
         templateFfiTypeInvalid,
         templateFfiTypeMismatch;
@@ -189,7 +188,7 @@ class _FfiUseSiteTransformer extends FfiTransformer {
         // TODO(http://dartbug.com/38721): Change this to an error after
         // package:ffi is no longer using sizeOf generically.
         if (!isFfiLibrary) {
-          _warningNativeTypeValid(nativeType, node);
+          _ensureNativeTypeValid(nativeType, node);
         }
 
         if (nativeType is InterfaceType) {
@@ -467,13 +466,7 @@ class _FfiUseSiteTransformer extends FfiTransformer {
             node.receiver.getStaticType(_staticTypeContext);
         final DartType nativeType = _pointerTypeGetTypeArg(pointerType);
 
-        _warningNativeTypeValid(nativeType, node);
+        _ensureNativeTypeValid(nativeType, node);
-
-        // TODO(http://dartbug.com/38721): Change this to an error.
-        if (nativeType is TypeParameterType) {
-          // Do not rewire generic invocations.
-          return node;
-        }
 
         Expression inlineSizeOf = _inlineSizeOf(nativeType);
         if (inlineSizeOf != null) {
@@ -541,22 +534,6 @@ class _FfiUseSiteTransformer extends FfiTransformer {
     }
   }
 
-  void _warningNativeTypeValid(DartType nativeType, Expression node,
-      {bool allowHandle: false, bool allowStructItself = true}) {
-    if (!_nativeTypeValid(nativeType,
-        allowStructs: true,
-        allowStructItself: allowStructItself,
-        allowHandle: allowHandle)) {
-      diagnosticReporter.report(
-          templateFfiNonConstantTypeArgumentWarning.withArguments(
-              nativeType, currentLibrary.isNonNullableByDefault),
-          node.fileOffset,
-          1,
-          node.location.file);
-      throw _FfiStaticTypeError();
-    }
-  }
-
   void _ensureNoEmptyStructs(DartType nativeType, Expression node) {
     // Error on structs with no fields.
     if (nativeType is InterfaceType) {

sdk/lib/_internal/vm/lib/ffi_allocation_patch.dart

@@ -12,6 +12,7 @@ extension AllocatorAlloc on Allocator {
   // TODO(http://dartbug.com/39964): Add `alignmentOf<T>()` call.
   @patch
   Pointer<T> call<T extends NativeType>([int count = 1]) {
-    return this.allocate(sizeOf<T>() * count);
+    // This case should have been rewritten in pre-processing.
+    throw UnimplementedError("Pointer<$T>");
   }
 }

sdk/lib/_internal/vm/lib/ffi_patch.dart

@@ -26,19 +26,10 @@ int get _intPtrSize => (const [8, 4, 4])[_abi()];
 
 @patch
 int sizeOf<T extends NativeType>() {
-  // This is not super fast, but it is faster than a runtime entry.
+  // This case should have been rewritten in pre-processing.
-  // Hot loops with elementAt().load() do not use this sizeOf, elementAt is
+  throw UnimplementedError("$T");
-  // optimized per NativeType statically to prevent use of sizeOf at runtime.
-  final int? knownSize = _knownSizes[T];
-  if (knownSize != null) return knownSize;
-  if (T == IntPtr) return _intPtrSize;
-  if (T == Pointer) return _intPtrSize;
-  // For structs we fall back to a runtime entry.
-  return _sizeOf<T>();
 }
 
-int _sizeOf<T extends NativeType>() native "Ffi_sizeOf";
-
 @pragma("vm:recognized", "other")
 Pointer<T> _fromAddress<T extends NativeType>(int ptr) native "Ffi_fromAddress";
 
@@ -98,11 +89,13 @@ class Pointer<T extends NativeType> {
   @pragma("vm:recognized", "other")
   int get address native "Ffi_address";
 
-  // For statically known types, this is rewired.
+  // For statically known types, this is rewritten.
-  // (Method sizeOf is slow, see notes above.)
   @patch
-  Pointer<T> elementAt(int index) =>
+  Pointer<T> elementAt(int index) {
-      Pointer.fromAddress(address + sizeOf<T>() * index);
+    // This case should have been rewritten in pre-processing.
+    // Only dynamic invocations are not rewritten in pre-processing.
+    throw UnsupportedError("Pointer.elementAt cannot be called dynamically.");
+  }
 
   @patch
   Pointer<T> _offsetBy(int offsetInBytes) =>

sdk/lib/ffi/ffi.dart

@@ -24,9 +24,7 @@ part "struct.dart";
 ///
 /// Includes padding and alignment of structs.
 ///
-/// Support for invoking this function with non-constant [T] will be removed in
+/// This function must be invoked with a compile-time constant [T].
-/// the next stable version of Dart and it will become mandatory to invoke it
-/// with a compile-time constant [T].
 external int sizeOf<T extends NativeType>();
 
 /// Represents a pointer into the native C memory corresponding to "NULL", e.g.
@@ -65,9 +63,10 @@ class Pointer<T extends NativeType> extends NativeType {
 
   /// Pointer arithmetic (takes element size into account).
   ///
-  /// Support for invoking this method with non-constant [T] will be removed in
+  /// This method must be invoked with a compile-time constant [T].
-  /// the next stable version of Dart and it will become mandatory to invoke it
+  ///
-  /// with a compile-time constant [T].
+  /// Does not accept dynamic invocations -- where the type of the receiver is
+  /// [dynamic].
   external Pointer<T> elementAt(int index);
 
   /// Cast Pointer<T> to a Pointer<V>.

tests/ffi/data_test.dart

@@ -449,7 +449,7 @@ void testDynamicInvocation() {
     final int i = p.value;
   });
   Expect.throws(() => p.value = 1);
-  p.elementAt(5); // Works, but is slow.
+  Expect.throws(() => p.elementAt(5));
   final int addr = p.address;
   final Pointer<Int16> p2 = p.cast<Int16>();
   calloc.free(p);

tests/ffi/vmspecific_static_checks_test.dart

@@ -625,7 +625,7 @@ T genericRef3<T extends Struct>(Pointer<T> p) => //# 1202: compile-time error
 void testSizeOfGeneric() {
   int generic<T extends Pointer>() {
     int size = sizeOf<IntPtr>();
-    size = sizeOf<T>(); //# 1300: ok
+    size = sizeOf<T>(); //# 1300: compile-time error
     return size;
   }
 
@@ -634,7 +634,7 @@ void testSizeOfGeneric() {
 
 void testSizeOfNativeType() {
   try {
-    sizeOf(); //# 1301: ok
+    sizeOf(); //# 1301: compile-time error
   } catch (e) {
     print(e);
   }
@@ -643,7 +643,7 @@ void testSizeOfNativeType() {
 void testElementAtGeneric() {
   Pointer<T> generic<T extends NativeType>(Pointer<T> pointer) {
     Pointer<T> returnValue = pointer;
-    returnValue = returnValue.elementAt(1); //# 1310: ok
+    returnValue = returnValue.elementAt(1); //# 1310: compile-time error
     return returnValue;
   }
 
@@ -657,6 +657,6 @@ void testElementAtNativeType() {
   Pointer<Int8> p = calloc();
   p.elementAt(1);
   Pointer<NativeType> p2 = p;
-  p2.elementAt(1); //# 1311: ok
+  p2.elementAt(1); //# 1311: compile-time error
   calloc.free(p);
 }

tests/ffi_2/data_test.dart

@@ -449,7 +449,7 @@ void testDynamicInvocation() {
     final int i = p.value;
   });
   Expect.throws(() => p.value = 1);
-  p.elementAt(5); // Works, but is slow.
+  Expect.throws(() => p.elementAt(5));
   final int addr = p.address;
   final Pointer<Int16> p2 = p.cast<Int16>();
   calloc.free(p);

tests/ffi_2/vmspecific_static_checks_test.dart

@@ -623,7 +623,7 @@ T genericRef3<T extends Struct>(Pointer<T> p) => //# 1202: compile-time error
 void testSizeOfGeneric() {
   int generic<T extends Pointer>() {
     int size = sizeOf<IntPtr>();
-    size = sizeOf<T>(); //# 1300: ok
+    size = sizeOf<T>(); //# 1300: compile-time error
     return size;
   }
 
@@ -632,7 +632,7 @@ void testSizeOfGeneric() {
 
 void testSizeOfNativeType() {
   try {
-    sizeOf(); //# 1301: ok
+    sizeOf(); //# 1301: compile-time error
   } catch (e) {
     print(e);
   }
@@ -641,7 +641,7 @@ void testSizeOfNativeType() {
 void testElementAtGeneric() {
   Pointer<T> generic<T extends NativeType>(Pointer<T> pointer) {
     Pointer<T> returnValue = pointer;
-    returnValue = returnValue.elementAt(1); //# 1310: ok
+    returnValue = returnValue.elementAt(1); //# 1310: compile-time error
     return returnValue;
   }
 
@@ -655,6 +655,6 @@ void testElementAtNativeType() {
   Pointer<Int8> p = calloc();
   p.elementAt(1);
   Pointer<NativeType> p2 = p;
-  p2.elementAt(1); //# 1311: ok
+  p2.elementAt(1); //# 1311: compile-time error
   calloc.free(p);
 }