Function instantiateSignature

test/fixtures/snapshot/typescript.js:63350–63372

(signature, mapper, eraseTypeParameters)

            return createTypePredicate(predicate.kind, predicate.parameterName, predicate.parameterIndex, instantiateType(predicate.type, mapper));
        }
        function instantiateSignature(signature, mapper, eraseTypeParameters) {
            var freshTypeParameters;
            if (signature.typeParameters && !eraseTypeParameters) {
                // First create a fresh set of type parameters, then include a mapping from the old to the
                // new type parameters in the mapper function. Finally store this mapper in the new type
                // parameters such that we can use it when instantiating constraints.
                freshTypeParameters = ts.map(signature.typeParameters, cloneTypeParameter);
                mapper = combineTypeMappers(createTypeMapper(signature.typeParameters, freshTypeParameters), mapper);
                for (var _i = 0, freshTypeParameters_1 = freshTypeParameters; _i < freshTypeParameters_1.length; _i++) {
                    var tp = freshTypeParameters_1[_i];
                    tp.mapper = mapper;
                }
            }
            // Don't compute resolvedReturnType and resolvedTypePredicate now,
            // because using `mapper` now could trigger inferences to become fixed. (See `createInferenceContext`.)
            // See GH#17600.
            var result = createSignature(signature.declaration, freshTypeParameters, signature.thisParameter && instantiateSymbol(signature.thisParameter, mapper), instantiateList(signature.parameters, mapper, instantiateSymbol), 
            /*resolvedReturnType*/ undefined, 
            /*resolvedTypePredicate*/ undefined, signature.minArgumentCount, signature.flags & 39 /* SignatureFlags.PropagatingFlags */);
            result.target = signature;
            result.mapper = mapper;
            return result;
        }
        function instantiateSymbol(symbol, mapper) {
            var links = getSymbolLinks(symbol);
            if (links.type && !couldContainTypeVariables(links.type)) {