Validate attributes on function return types

Functions that are not entry points cannot have any attributes on
their return types.

Validate the builtin store types for return types.

Bug: tint:851
Change-Id: I718356b3ab06db4b4502a53b81790e4de0ecfeac
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/56100
Auto-Submit: James Price <jrprice@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/resolver/builtins_validation_test.cc

@@ -39,6 +39,18 @@ TEST_F(ResolverBuiltinsValidationTest, PositionNotF32_Struct_Fail) {
             "12:34 error: store type of builtin(position) must be 'vec4<f32>'");
 }
 
+TEST_F(ResolverBuiltinsValidationTest, PositionNotF32_ReturnType_Fail) {
+  // [[stage(vertex)]]
+  // fn main() -> [[builtin(position)]] f32 { return 1.0; }
+  Func("main", {}, ty.f32(), {Return(1.0f)},
+       {Stage(ast::PipelineStage::kVertex)},
+       {Builtin(Source{{12, 34}}, ast::Builtin::kPosition)});
+
+  EXPECT_FALSE(r()->Resolve());
+  EXPECT_EQ(r()->error(),
+            "12:34 error: store type of builtin(position) must be 'vec4<f32>'");
+}
+
 TEST_F(ResolverBuiltinsValidationTest, FragDepthNotF32_Struct_Fail) {
   // struct MyInputs {
   //   [[builtin(kFragDepth)]] p: i32;
@@ -77,6 +89,18 @@ TEST_F(ResolverBuiltinsValidationTest, SampleMaskNotU32_Struct_Fail) {
             "12:34 error: store type of builtin(sample_mask) must be 'u32'");
 }
 
+TEST_F(ResolverBuiltinsValidationTest, SampleMaskNotU32_ReturnType_Fail) {
+  // [[stage(fragment)]]
+  // fn main() -> [[builtin(sample_mask)]] i32 { return 1; }
+  Func("main", {}, ty.i32(), {Return(1)},
+       {Stage(ast::PipelineStage::kFragment)},
+       {Builtin(Source{{12, 34}}, ast::Builtin::kSampleMask)});
+
+  EXPECT_FALSE(r()->Resolve());
+  EXPECT_EQ(r()->error(),
+            "12:34 error: store type of builtin(sample_mask) must be 'u32'");
+}
+
 TEST_F(ResolverBuiltinsValidationTest, SampleMaskIsNotU32_Fail) {
   // [[stage(fragment)]]
   // fn fs_main(

src/resolver/decoration_validation_test.cc

@@ -230,8 +230,7 @@ TEST_P(FunctionReturnTypeDecorationTest, IsValid) {
   auto& params = GetParam();
 
   Func("main", ast::VariableList{}, ty.f32(), ast::StatementList{Return(1.f)},
-       ast::DecorationList{Stage(ast::PipelineStage::kCompute)},
+       {}, createDecorations({}, *this, params.kind));
-       createDecorations({}, *this, params.kind));
 
   if (params.should_pass) {
     EXPECT_TRUE(r()->Resolve()) << r()->error();
@@ -244,6 +243,41 @@ TEST_P(FunctionReturnTypeDecorationTest, IsValid) {
 INSTANTIATE_TEST_SUITE_P(
     ResolverDecorationValidationTest,
     FunctionReturnTypeDecorationTest,
+    testing::Values(TestParams{DecorationKind::kAlign, false},
+                    TestParams{DecorationKind::kBinding, false},
+                    TestParams{DecorationKind::kBuiltin, false},
+                    TestParams{DecorationKind::kGroup, false},
+                    TestParams{DecorationKind::kLocation, false},
+                    TestParams{DecorationKind::kOverride, false},
+                    TestParams{DecorationKind::kOffset, false},
+                    TestParams{DecorationKind::kSize, false},
+                    TestParams{DecorationKind::kStage, false},
+                    TestParams{DecorationKind::kStride, false},
+                    TestParams{DecorationKind::kStructBlock, false},
+                    TestParams{DecorationKind::kWorkgroup, false},
+                    TestParams{DecorationKind::kBindingAndGroup, false}));
+
+using EntryPointReturnTypeDecorationTest = TestWithParams;
+TEST_P(EntryPointReturnTypeDecorationTest, IsValid) {
+  auto& params = GetParam();
+
+  Func("main", ast::VariableList{}, ty.vec4<f32>(),
+       {Return(Construct(ty.vec4<f32>(), 1.f))},
+       {Stage(ast::PipelineStage::kCompute)},
+       createDecorations({}, *this, params.kind));
+
+  if (params.should_pass) {
+    EXPECT_TRUE(r()->Resolve()) << r()->error();
+  } else {
+    EXPECT_FALSE(r()->Resolve()) << r()->error();
+    EXPECT_EQ(r()->error(),
+              "error: decoration is not valid for entry point return types");
+  }
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    ResolverDecorationValidationTest,
+    EntryPointReturnTypeDecorationTest,
     testing::Values(TestParams{DecorationKind::kAlign, false},
                     TestParams{DecorationKind::kBinding, false},
                     TestParams{DecorationKind::kBuiltin, true},
@@ -258,9 +292,9 @@ INSTANTIATE_TEST_SUITE_P(
                     TestParams{DecorationKind::kWorkgroup, false},
                     TestParams{DecorationKind::kBindingAndGroup, false}));
 
-TEST_F(FunctionReturnTypeDecorationTest, DuplicateDecoration) {
+TEST_F(EntryPointReturnTypeDecorationTest, DuplicateDecoration) {
   Func("main", ast::VariableList{}, ty.f32(), ast::StatementList{Return(1.f)},
-       ast::DecorationList{Stage(ast::PipelineStage::kCompute)},
+       ast::DecorationList{Stage(ast::PipelineStage::kFragment)},
        ast::DecorationList{
            Location(Source{{12, 34}}, 2),
            Location(Source{{56, 78}}, 3),

src/resolver/resolver.cc

@@ -1084,11 +1084,21 @@ bool Resolver::ValidateFunction(const ast::Function* func,
     }
 
     for (auto* deco : func->return_type_decorations()) {
-      if (!deco->IsAnyOf<ast::BuiltinDecoration, ast::LocationDecoration>()) {
+      if (!func->IsEntryPoint()) {
         AddError("decoration is not valid for function return types",
                  deco->source());
         return false;
       }
+
+      if (auto* builtin = deco->As<ast::BuiltinDecoration>()) {
+        if (!ValidateBuiltinDecoration(builtin, info->return_type)) {
+          return false;
+        }
+      } else if (!deco->Is<ast::LocationDecoration>()) {
+        AddError("decoration is not valid for entry point return types",
+                 deco->source());
+        return false;
+      }
     }
   }