fix(transformer/legacy-decorator): correct generating metadata for getter/setter methods (#14495)

* Fixes: #14493

Getter and setter methods should not have `design:returntype` metadata according to TypeScript's `emitDecoratorMetadata` behavior. They should only have `design:type` and `design:paramtypes`.

**And `design:type` is different for the getter and setter:**

Getter: `design:type` is the same as the return type of method.
Setter: `design:type` is the same as the type of the first parameter of the method

Author: Dunqing

crates/oxc_transformer/src/decorator/legacy/metadata.rs

@@ -113,16 +113,25 @@ enum EnumType {
     Object,
 }
 
+/// Metadata for decorated methods
+pub(super) struct MethodMetadata<'a> {
+    /// The `design:type` metadata expression
+    pub r#type: Expression<'a>,
+    /// The `design:paramtypes` metadata expression
+    pub param_types: Expression<'a>,
+    /// The `design:returntype` metadata expression (optional, omitted for getters/setters)
+    pub return_type: Option<Expression<'a>>,
+}
+
 pub struct LegacyDecoratorMetadata<'a, 'ctx> {
     ctx: &'ctx TransformCtx<'a>,
-    /// Stack of method metadata arrays, each array contains 3 expressions:
-    /// `[design:type, design:paramtypes, design:returntype]`
+    /// Stack of method metadata.
     ///
     /// Only the method that needs to be pushed onto a stack is the method metadata,
     /// which should be inserted after all real decorators. However, method parameters
     /// will be processed before the metadata generation, so we need to temporarily store
     /// them in a stack and pop them when in exit_method_definition.
-    method_metadata_stack: SparseStack<[Expression<'a>; 3]>,
+    method_metadata_stack: SparseStack<MethodMetadata<'a>>,
     /// Stack of constructor metadata expressions, each expression
     /// is the `design:paramtypes`.
     ///
@@ -182,7 +191,7 @@ impl<'a> Traverse<'a, TransformState<'a>> for LegacyDecoratorMetadata<'a, '_> {
                 && constructor.value.params.items.iter().all(|param| param.decorators.is_empty()))
         {
             let serialized_type =
-                self.serialize_parameter_types_of_node(&constructor.value.params, ctx);
+                self.serialize_parameters_types_of_node(&constructor.value.params, ctx);
 
             Some(self.create_metadata("design:paramtypes", serialized_type, ctx))
         } else {
@@ -208,18 +217,32 @@ impl<'a> Traverse<'a, TransformState<'a>> for LegacyDecoratorMetadata<'a, '_> {
                 || method.value.params.items.iter().any(|param| !param.decorators.is_empty()));
 
         let metadata = is_decorated.then(|| {
-            [
-                self.create_metadata("design:type", Self::global_function(ctx), ctx),
-                {
-                    let serialized_type =
-                        self.serialize_parameter_types_of_node(&method.value.params, ctx);
-                    self.create_metadata("design:paramtypes", serialized_type, ctx)
-                },
-                {
-                    let serialized_type = self.serialize_return_type_of_node(&method.value, ctx);
-                    self.create_metadata("design:returntype", serialized_type, ctx)
-                },
-            ]
+            // TypeScript only emits `design:returntype` for regular methods,
+            // not for getters or setters.
+
+            let (design_type, return_type) = if method.kind.is_get() {
+                // For getters, the design type is the type of the property
+                (self.serialize_return_type_of_node(&method.value, ctx), None)
+            } else if method.kind.is_set()
+                && let Some(param) = method.value.params.items.first()
+            {
+                // For setters, the design type is the type of the first parameter
+                (self.serialize_parameter_types_of_node(param, ctx), None)
+            } else {
+                // For methods, the design type is always `Function`
+                (
+                    Self::global_function(ctx),
+                    Some(self.serialize_return_type_of_node(&method.value, ctx)),
+                )
+            };
+
+            let param_types = self.serialize_parameters_types_of_node(&method.value.params, ctx);
+
+            MethodMetadata {
+                r#type: self.create_metadata("design:type", design_type, ctx),
+                param_types: self.create_metadata("design:paramtypes", param_types, ctx),
+                return_type: return_type.map(|t| self.create_metadata("design:returntype", t, ctx)),
+            }
         });
 
         self.method_metadata_stack.push(metadata);
@@ -302,7 +325,7 @@ impl<'a> LegacyDecoratorMetadata<'a, '_> {
         enum_type
     }
 
-    pub fn pop_method_metadata(&mut self) -> Option<[Expression<'a>; 3]> {
+    pub fn pop_method_metadata(&mut self) -> Option<MethodMetadata<'a>> {
         self.method_metadata_stack.pop()
     }
 
@@ -407,21 +430,15 @@ impl<'a> LegacyDecoratorMetadata<'a, '_> {
     }
 
     /// Serializes the type of a node for use with decorator type metadata.
-    fn serialize_parameter_types_of_node(
+    fn serialize_parameters_types_of_node(
         &mut self,
         params: &FormalParameters<'a>,
         ctx: &mut TraverseCtx<'a>,
     ) -> Expression<'a> {
         let mut elements =
             ctx.ast.vec_with_capacity(params.items.len() + usize::from(params.rest.is_some()));
         elements.extend(params.items.iter().map(|param| {
-            let type_annotation = match &param.pattern.kind {
-                BindingPatternKind::AssignmentPattern(pattern) => {
-                    pattern.left.type_annotation.as_ref()
-                }
-                _ => param.pattern.type_annotation.as_ref(),
-            };
-            ArrayExpressionElement::from(self.serialize_type_annotation(type_annotation, ctx))
+            ArrayExpressionElement::from(self.serialize_parameter_types_of_node(param, ctx))
         }));
 
         if let Some(rest) = &params.rest {
@@ -432,6 +449,18 @@ impl<'a> LegacyDecoratorMetadata<'a, '_> {
         ctx.ast.expression_array(SPAN, elements)
     }
 
+    fn serialize_parameter_types_of_node(
+        &mut self,
+        param: &FormalParameter<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) -> Expression<'a> {
+        let type_annotation = match &param.pattern.kind {
+            BindingPatternKind::AssignmentPattern(pattern) => pattern.left.type_annotation.as_ref(),
+            _ => param.pattern.type_annotation.as_ref(),
+        };
+        self.serialize_type_annotation(type_annotation, ctx)
+    }
+
     /// Serializes the return type of a node for use with decorator type metadata.
     fn serialize_return_type_of_node(
         &mut self,

crates/oxc_transformer/src/decorator/legacy/mod.rs

@@ -999,7 +999,11 @@ impl<'a> LegacyDecorator<'a, '_> {
                     decorations.push(ArrayExpressionElement::from(metadata));
                 }
             } else if let Some(metadata) = self.metadata.pop_method_metadata() {
-                decorations.extend(metadata.map(ArrayExpressionElement::from));
+                decorations.push(ArrayExpressionElement::from(metadata.r#type));
+                decorations.push(ArrayExpressionElement::from(metadata.param_types));
+                if let Some(return_type) = metadata.return_type {
+                    decorations.push(ArrayExpressionElement::from(return_type));
+                }
             }
         }
 

tasks/coverage/snapshots/semantic_typescript.snap

@@ -8672,7 +8672,7 @@ rebuilt        : [ReferenceId(13)]
 
 semantic Error: tasks/coverage/typescript/tests/cases/compiler/decoratorMetadataElidedImport.ts
 Symbol reference IDs mismatch for "Observable":
-after transform: SymbolId(0): [ReferenceId(2), ReferenceId(8), ReferenceId(9)]
+after transform: SymbolId(0): [ReferenceId(2), ReferenceId(4), ReferenceId(5)]
 rebuilt        : SymbolId(0): [ReferenceId(12), ReferenceId(13)]
 
 semantic Error: tasks/coverage/typescript/tests/cases/compiler/decoratorMetadataElidedImportOnDeclare.ts
@@ -8727,22 +8727,22 @@ Reference symbol mismatch for "decorator":
 after transform: SymbolId(0) "decorator"
 rebuilt        : <None>
 Reference flags mismatch for "Promise":
-after transform: ReferenceId(26): ReferenceFlags(Read | Type)
+after transform: ReferenceId(30): ReferenceFlags(Read | Type)
 rebuilt        : ReferenceId(28): ReferenceFlags(Read)
 Reference flags mismatch for "Promise":
-after transform: ReferenceId(27): ReferenceFlags(Read | Type)
+after transform: ReferenceId(31): ReferenceFlags(Read | Type)
 rebuilt        : ReferenceId(29): ReferenceFlags(Read)
 Reference flags mismatch for "Promise":
-after transform: ReferenceId(32): ReferenceFlags(Read | Type)
+after transform: ReferenceId(25): ReferenceFlags(Read | Type)
 rebuilt        : ReferenceId(34): ReferenceFlags(Read)
 Reference flags mismatch for "Promise":
-after transform: ReferenceId(33): ReferenceFlags(Read | Type)
+after transform: ReferenceId(26): ReferenceFlags(Read | Type)
 rebuilt        : ReferenceId(35): ReferenceFlags(Read)
 Unresolved references mismatch:
 after transform: ["Function", "MethodDecorator", "Object", "Promise", "require"]
 rebuilt        : ["Function", "Object", "Promise", "decorator", "require"]
 Unresolved reference IDs mismatch for "Promise":
-after transform: [ReferenceId(3), ReferenceId(5), ReferenceId(6), ReferenceId(11), ReferenceId(19), ReferenceId(26), ReferenceId(27), ReferenceId(32), ReferenceId(33)]
+after transform: [ReferenceId(3), ReferenceId(5), ReferenceId(6), ReferenceId(9), ReferenceId(17), ReferenceId(25), ReferenceId(26), ReferenceId(30), ReferenceId(31)]
 rebuilt        : [ReferenceId(12), ReferenceId(20), ReferenceId(28), ReferenceId(29), ReferenceId(34), ReferenceId(35)]
 
 semantic Error: tasks/coverage/typescript/tests/cases/compiler/decoratorMetadataRestParameterWithImportedType.ts
@@ -8864,7 +8864,7 @@ rebuilt        : ["Object", "database"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/compiler/decoratorReferenceOnOtherProperty.ts
 Symbol reference IDs mismatch for "Yoha":
-after transform: SymbolId(0): [ReferenceId(1), ReferenceId(5), ReferenceId(6)]
+after transform: SymbolId(0): [ReferenceId(1), ReferenceId(4), ReferenceId(5)]
 rebuilt        : SymbolId(0): [ReferenceId(8), ReferenceId(9)]
 
 semantic Error: tasks/coverage/typescript/tests/cases/compiler/decoratorReferences.ts
@@ -35962,8 +35962,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "TypedPropertyDescriptor", "require"]
-rebuilt        : ["Function", "dec", "require"]
+after transform: ["TypedPropertyDescriptor", "require"]
+rebuilt        : ["dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/decorators/class/accessor/decoratorOnClassAccessor2.ts
 Bindings mismatch:
@@ -35976,8 +35976,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "TypedPropertyDescriptor", "require"]
-rebuilt        : ["Function", "dec", "require"]
+after transform: ["TypedPropertyDescriptor", "require"]
+rebuilt        : ["dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/decorators/class/accessor/decoratorOnClassAccessor4.ts
 Bindings mismatch:
@@ -35990,8 +35990,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Number", "TypedPropertyDescriptor", "require"]
-rebuilt        : ["Function", "Number", "dec", "require"]
+after transform: ["Number", "TypedPropertyDescriptor", "require"]
+rebuilt        : ["Number", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/decorators/class/accessor/decoratorOnClassAccessor5.ts
 Bindings mismatch:
@@ -36004,8 +36004,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Number", "TypedPropertyDescriptor", "require"]
-rebuilt        : ["Function", "Number", "dec", "require"]
+after transform: ["Number", "TypedPropertyDescriptor", "require"]
+rebuilt        : ["Number", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/decorators/class/accessor/decoratorOnClassAccessor8.ts
 Bindings mismatch:
@@ -36033,8 +36033,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Number", "TypedPropertyDescriptor", "require"]
-rebuilt        : ["Function", "Number", "dec", "require"]
+after transform: ["Number", "TypedPropertyDescriptor", "require"]
+rebuilt        : ["Number", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/decorators/class/constructor/decoratorOnClassConstructor3.ts
 Unresolved references mismatch:
@@ -38551,8 +38551,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "TypedPropertyDescriptor"]
-rebuilt        : ["Function", "dec"]
+after transform: ["TypedPropertyDescriptor"]
+rebuilt        : ["dec"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/es6/decorators/class/decoratorOnClass1.es6.ts
 Bindings mismatch:
@@ -39372,10 +39372,10 @@ Bindings mismatch:
 after transform: ScopeId(0): ["C", "_decorate", "_decorateMetadata", "_method", "_method2", "dec", "method3"]
 rebuilt        : ScopeId(0): ["C", "_decorate", "_decorateMetadata", "_method", "_method2", "method3"]
 Reference flags mismatch for "_method":
-after transform: ReferenceId(39): ReferenceFlags(Read | Write)
+after transform: ReferenceId(31): ReferenceFlags(Read | Write)
 rebuilt        : ReferenceId(2): ReferenceFlags(Write)
 Reference flags mismatch for "_method2":
-after transform: ReferenceId(48): ReferenceFlags(Read | Write)
+after transform: ReferenceId(39): ReferenceFlags(Read | Write)
 rebuilt        : ReferenceId(4): ReferenceFlags(Write)
 Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
@@ -39396,8 +39396,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Object", "require"]
-rebuilt        : ["Function", "Object", "dec", "require"]
+after transform: ["Object", "require"]
+rebuilt        : ["Object", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/esDecorators/classDeclaration/accessors/esDecorators-classDeclaration-accessors-nonStaticPrivate.ts
 Bindings mismatch:
@@ -39410,18 +39410,18 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Object", "WeakSet", "require"]
-rebuilt        : ["Function", "Object", "WeakSet", "dec", "require"]
+after transform: ["Object", "WeakSet", "require"]
+rebuilt        : ["Object", "WeakSet", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/esDecorators/classDeclaration/accessors/esDecorators-classDeclaration-accessors-static.ts
 Bindings mismatch:
 after transform: ScopeId(0): ["C", "_decorate", "_decorateMetadata", "_method", "_method2", "dec", "method3"]
 rebuilt        : ScopeId(0): ["C", "_decorate", "_decorateMetadata", "_method", "_method2", "method3"]
 Reference flags mismatch for "_method":
-after transform: ReferenceId(39): ReferenceFlags(Read | Write)
+after transform: ReferenceId(31): ReferenceFlags(Read | Write)
 rebuilt        : ReferenceId(2): ReferenceFlags(Write)
 Reference flags mismatch for "_method2":
-after transform: ReferenceId(48): ReferenceFlags(Read | Write)
+after transform: ReferenceId(39): ReferenceFlags(Read | Write)
 rebuilt        : ReferenceId(4): ReferenceFlags(Write)
 Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
@@ -39442,8 +39442,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Object", "require"]
-rebuilt        : ["Function", "Object", "dec", "require"]
+after transform: ["Object", "require"]
+rebuilt        : ["Object", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/esDecorators/classDeclaration/accessors/esDecorators-classDeclaration-accessors-staticPrivate.ts
 Bindings mismatch:
@@ -39453,13 +39453,13 @@ Symbol span mismatch for "D":
 after transform: SymbolId(3): Span { start: 137, end: 138 }
 rebuilt        : SymbolId(9): Span { start: 0, end: 0 }
 Symbol reference IDs mismatch for "D":
-after transform: SymbolId(3): [ReferenceId(23), ReferenceId(25)]
-rebuilt        : SymbolId(9): [ReferenceId(20), ReferenceId(30), ReferenceId(33)]
+after transform: SymbolId(3): [ReferenceId(20), ReferenceId(22)]
+rebuilt        : SymbolId(9): [ReferenceId(17), ReferenceId(27), ReferenceId(30)]
 Symbol span mismatch for "D":
 after transform: SymbolId(14): Span { start: 0, end: 0 }
 rebuilt        : SymbolId(10): Span { start: 137, end: 138 }
 Symbol reference IDs mismatch for "D":
-after transform: SymbolId(14): [ReferenceId(28)]
+after transform: SymbolId(14): [ReferenceId(25)]
 rebuilt        : SymbolId(10): []
 Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
@@ -39474,8 +39474,8 @@ Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"
 rebuilt        : <None>
 Unresolved references mismatch:
-after transform: ["Function", "Object", "require"]
-rebuilt        : ["Function", "Object", "dec", "require"]
+after transform: ["Object", "require"]
+rebuilt        : ["Object", "dec", "require"]
 
 semantic Error: tasks/coverage/typescript/tests/cases/conformance/esDecorators/classDeclaration/classSuper/esDecorators-classDeclaration-classSuper.1.ts
 Bindings mismatch:
@@ -40482,7 +40482,7 @@ Bindings mismatch:
 after transform: ScopeId(0): ["_C", "_decorateMetadata", "_defineProperty", "_get_x", "_method", "_set_x", "_y", "dec"]
 rebuilt        : ScopeId(0): ["_C", "_decorateMetadata", "_defineProperty", "_get_x", "_method", "_set_x", "_y"]
 Symbol reference IDs mismatch for "_decorateMetadata":
-after transform: SymbolId(10): [ReferenceId(24), ReferenceId(25), ReferenceId(26), ReferenceId(28), ReferenceId(29), ReferenceId(30), ReferenceId(32), ReferenceId(34), ReferenceId(35), ReferenceId(37), ReferenceId(39), ReferenceId(41), ReferenceId(42), ReferenceId(43), ReferenceId(45), ReferenceId(46), ReferenceId(47), ReferenceId(49), ReferenceId(51), ReferenceId(52), ReferenceId(54), ReferenceId(56)]
+after transform: SymbolId(10): [ReferenceId(24), ReferenceId(25), ReferenceId(26), ReferenceId(27), ReferenceId(28), ReferenceId(31), ReferenceId(32), ReferenceId(34), ReferenceId(36), ReferenceId(38), ReferenceId(39), ReferenceId(40), ReferenceId(41), ReferenceId(42), ReferenceId(45), ReferenceId(46), ReferenceId(48), ReferenceId(50)]
 rebuilt        : SymbolId(1): []
 Reference symbol mismatch for "dec":
 after transform: SymbolId(0) "dec"