Enter signature scope in SerializeReturnTypeForSignature (#3572)

Author: jakebailey

internal/checker/nodebuilder.go

@@ -117,7 +117,10 @@ func (b *NodeBuilder) IndexInfoToIndexSignatureDeclaration(info *IndexInfo, encl
 func (b *NodeBuilder) SerializeReturnTypeForSignature(signatureDeclaration *ast.Node, enclosingDeclaration *ast.Node, flags nodebuilder.Flags, internalFlags nodebuilder.InternalFlags, tracker nodebuilder.SymbolTracker) *ast.Node {
 	b.enterContext(enclosingDeclaration, flags, internalFlags, tracker)
 	signature := b.impl.ch.getSignatureFromDeclaration(signatureDeclaration)
-	return b.exitContext(b.impl.serializeReturnTypeForSignature(signature, true))
+	_, cleanup := b.impl.enterSignatureScope(signature)
+	result := b.impl.serializeReturnTypeForSignature(signature, true)
+	cleanup()
+	return b.exitContext(result)
 }
 
 func (b *NodeBuilder) SerializeTypeParametersForSignature(signatureDeclaration *ast.Node, enclosingDeclaration *ast.Node, flags nodebuilder.Flags, internalFlags nodebuilder.InternalFlags, tracker nodebuilder.SymbolTracker) []*ast.Node {

internal/checker/nodebuilderimpl.go

@@ -1823,8 +1823,7 @@ type SignatureToSignatureDeclarationOptions struct {
 func (b *NodeBuilderImpl) signatureToSignatureDeclarationHelper(signature *Signature, kind ast.Kind, options *SignatureToSignatureDeclarationOptions) *ast.Node {
 	var typeParameters []*ast.Node
 
-	expandedParams := b.ch.getExpandedParameters(signature, true /*skipUnionExpanding*/)[0]
-	cleanup := b.enterNewScope(signature.declaration, expandedParams, signature.typeParameters, signature.parameters, signature.mapper)
+	expandedParams, cleanup := b.enterSignatureScope(signature)
 	b.ctx.approximateLength += 3
 	// Usually a signature contributes a few more characters than this, but 3 is the minimum
 

internal/checker/nodebuilderscopes.go

@@ -62,6 +62,12 @@ func (b *NodeBuilderImpl) addSymbolTypeToContext(symbol *ast.Symbol, t *Type) fu
 	}
 }
 
+func (b *NodeBuilderImpl) enterSignatureScope(signature *Signature) (expandedParams []*ast.Symbol, cleanup func()) {
+	expandedParams = b.ch.getExpandedParameters(signature, true /*skipUnionExpanding*/)[0]
+	cleanup = b.enterNewScope(signature.declaration, expandedParams, signature.typeParameters, signature.parameters, signature.mapper)
+	return expandedParams, cleanup
+}
+
 func (b *NodeBuilderImpl) enterNewScope(declaration *ast.Node, expandedParams []*ast.Symbol, typeParameters []*Type, originalParameters []*ast.Symbol, mapper *TypeMapper) func() {
 	cleanupContext := cloneNodeBuilderContext(b.ctx)
 	// For regular function/method declarations, the enclosing declaration will already be signature.declaration,

testdata/baselines/reference/submodule/compiler/declarationEmitNestedGenerics.js

@@ -24,5 +24,5 @@ function g(x) {
 
 
 //// [declarationEmitNestedGenerics.d.ts]
-declare function f<T>(p: T): <T>(x: T) => typeof p;
+declare function f<T>(p: T): <T_1>(x: T_1) => typeof p;
 declare function g<T>(x: T): T extends (infer T_1)[] ? T_1 : T;

testdata/baselines/reference/submodule/compiler/declarationEmitShadowing.js

@@ -37,20 +37,4 @@ function needsRenameForShadowing() {
 export declare class A<T = any> {
     readonly ShadowedButDoesNotRequireRenaming: <T_1>() => T_1;
 }
-export declare function needsRenameForShadowing<T>(): <T>(t: T_1, t2: T) => void;
-
-
-//// [DtsFileErrors]
-
-
-declarationEmitShadowing.d.ts(4,62): error TS2304: Cannot find name 'T_1'.
-
-
-==== declarationEmitShadowing.d.ts (1 errors) ====
-    export declare class A<T = any> {
-        readonly ShadowedButDoesNotRequireRenaming: <T_1>() => T_1;
-    }
-    export declare function needsRenameForShadowing<T>(): <T>(t: T_1, t2: T) => void;
-                                                                 ~~~
-!!! error TS2304: Cannot find name 'T_1'.
-    
+export declare function needsRenameForShadowing<T>(): <T_1>(t: T, t2: T_1) => void;

testdata/baselines/reference/submodule/conformance/typeParametersAvailableInNestedScope3.js

@@ -31,10 +31,10 @@ function foo(v) {
 
 //// [typeParametersAvailableInNestedScope3.d.ts]
 declare function foo<T>(v: T): {
-    a: <T>(a: T) => T;
+    a: <T_1>(a: T_1) => T_1;
     b: () => T;
-    c: <T>(v: T) => {
-        a: <T_1>(a: T_1) => T_1;
-        b: () => T;
+    c: <T_1>(v: T_1) => {
+        a: <T_2>(a: T_2) => T_2;
+        b: () => T_1;
     };
 };

testdata/baselines/reference/submoduleAccepted/compiler/declarationEmitNestedGenerics.js.diff

@@ -1056,11 +1056,6 @@ compiler/declarationEmitClassMemberWithComputedPropertyName.js.diff
 compiler/isolatedDeclarationsLiterals.js.diff
 conformance/constAssertions.js.diff
 
-## Type parameter disambiguation suffixes (`_1`, `_2`) removed in nested/overlapping scopes (shadowing matches runtime semantics; `_1` suffixes were unnecessary)
-## Inner generic type parameters shadow outer ones with the same name instead of being renamed
-compiler/declarationEmitNestedGenerics.js.diff
-conformance/typeParametersAvailableInNestedScope3.js.diff
-
 ## Comma expressions in emitted JS are now parenthesized for correctness (parenthesizing comma expressions prevents precedence bugs)
 ## `a, b` in computed properties and JSX context now emitted as `(a, b)`
 conformance/jsxCheckJsxNoTypeArgumentsAllowed.js.diff