Expose method for retrieving inferred generic type arguments for a si…

…gnature on the TypeChecker (microsoft#59637)
tristanmenzel · Jan 21, 2025 · 3e97a7d · 3e97a7d
1 parent b78f466
commit 3e97a7d
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diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -1931,8 +1931,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         isTypeParameterPossiblyReferenced,
         typeHasCallOrConstructSignatures,
         getSymbolFlags,
+        getTypeArgumentsForResolvedSignature,
     };
 
+    function getTypeArgumentsForResolvedSignature(signature: Signature) {
+        if (signature.mapper === undefined) return undefined;
+        return instantiateTypes((signature.target || signature).typeParameters, signature.mapper);
+    }
+
     function getCandidateSignaturesForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node) {
         const candidatesSet = new Set<Signature>();
         const candidates: Signature[] = [];

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -5439,6 +5439,8 @@ export interface TypeChecker {
     /** @internal */ typeHasCallOrConstructSignatures(type: Type): boolean;
     /** @internal */ getSymbolFlags(symbol: Symbol): SymbolFlags;
     /** @internal */ fillMissingTypeArguments(typeArguments: readonly Type[], typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[];
+
+    getTypeArgumentsForResolvedSignature(signature: Signature): readonly Type[] | undefined;
 }
 
 /** @internal */

diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
@@ -6348,6 +6348,7 @@ declare namespace ts {
          * and the operation is cancelled, then it should be discarded, otherwise it is safe to keep.
          */
         runWithCancellationToken<T>(token: CancellationToken, cb: (checker: TypeChecker) => T): T;
+        getTypeArgumentsForResolvedSignature(signature: Signature): readonly Type[] | undefined;
     }
     enum NodeBuilderFlags {
         None = 0,