Function compareSignaturesIdentical

test/fixtures/snapshot/typescript.js:67299–67357

* See signatureRelatedTo, compareSignaturesIdentical

(source, target, partialMatch, ignoreThisTypes, ignoreReturnTypes, compareTypes)

         * See signatureRelatedTo, compareSignaturesIdentical
         */
        function compareSignaturesIdentical(source, target, partialMatch, ignoreThisTypes, ignoreReturnTypes, compareTypes) {
            // TODO (drosen): De-duplicate code between related functions.
            if (source === target) {
                return -1 /* Ternary.True */;
            }
            if (!(isMatchingSignature(source, target, partialMatch))) {
                return 0 /* Ternary.False */;
            }
            // Check that the two signatures have the same number of type parameters.
            if (ts.length(source.typeParameters) !== ts.length(target.typeParameters)) {
                return 0 /* Ternary.False */;
            }
            // Check that type parameter constraints and defaults match. If they do, instantiate the source
            // signature with the type parameters of the target signature and continue the comparison.
            if (target.typeParameters) {
                var mapper = createTypeMapper(source.typeParameters, target.typeParameters);
                for (var i = 0; i < target.typeParameters.length; i++) {
                    var s = source.typeParameters[i];
                    var t = target.typeParameters[i];
                    if (!(s === t || compareTypes(instantiateType(getConstraintFromTypeParameter(s), mapper) || unknownType, getConstraintFromTypeParameter(t) || unknownType) &&
                        compareTypes(instantiateType(getDefaultFromTypeParameter(s), mapper) || unknownType, getDefaultFromTypeParameter(t) || unknownType))) {
                        return 0 /* Ternary.False */;
                    }
                }
                source = instantiateSignature(source, mapper, /*eraseTypeParameters*/ true);
            }
            var result = -1 /* Ternary.True */;
            if (!ignoreThisTypes) {
                var sourceThisType = getThisTypeOfSignature(source);
                if (sourceThisType) {
                    var targetThisType = getThisTypeOfSignature(target);
                    if (targetThisType) {
                        var related = compareTypes(sourceThisType, targetThisType);
                        if (!related) {
                            return 0 /* Ternary.False */;
                        }
                        result &= related;
                    }
                }
            }
            var targetLen = getParameterCount(target);
            for (var i = 0; i < targetLen; i++) {
                var s = getTypeAtPosition(source, i);
                var t = getTypeAtPosition(target, i);
                var related = compareTypes(t, s);
                if (!related) {
                    return 0 /* Ternary.False */;
                }
                result &= related;
            }
            if (!ignoreReturnTypes) {
                var sourceTypePredicate = getTypePredicateOfSignature(source);
                var targetTypePredicate = getTypePredicateOfSignature(target);
                result &= sourceTypePredicate || targetTypePredicate ?
                    compareTypePredicatesIdentical(sourceTypePredicate, targetTypePredicate, compareTypes) :
                    compareTypes(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target));
            }
            return result;