Function getContextualSignature

test/fixtures/snapshot/typescript.js:73294–73331

(node)

        // all identical ignoring their return type, the result is same signature but with return type as
        // union type of return types from these signatures
        function getContextualSignature(node) {
            ts.Debug.assert(node.kind !== 169 /* SyntaxKind.MethodDeclaration */ || ts.isObjectLiteralMethod(node));
            var typeTagSignature = getSignatureOfTypeTag(node);
            if (typeTagSignature) {
                return typeTagSignature;
            }
            var type = getApparentTypeOfContextualType(node, 1 /* ContextFlags.Signature */);
            if (!type) {
                return undefined;
            }
            if (!(type.flags & 1048576 /* TypeFlags.Union */)) {
                return getContextualCallSignature(type, node);
            }
            var signatureList;
            var types = type.types;
            for (var _i = 0, types_19 = types; _i < types_19.length; _i++) {
                var current = types_19[_i];
                var signature = getContextualCallSignature(current, node);
                if (signature) {
                    if (!signatureList) {
                        // This signature will contribute to contextual union signature
                        signatureList = [signature];
                    }
                    else if (!compareSignaturesIdentical(signatureList[0], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ true, /*ignoreReturnTypes*/ true, compareTypesIdentical)) {
                        // Signatures aren't identical, do not use
                        return undefined;
                    }
                    else {
                        // Use this signature for contextual union signature
                        signatureList.push(signature);
                    }
                }
            }
            // Result is union of signatures collected (return type is union of return types of this signature set)
            if (signatureList) {
                return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList);
            }
        }
        function checkSpreadExpression(node, checkMode) {
            if (languageVersion < 2 /* ScriptTarget.ES2015 */) {
                checkExternalEmitHelpers(node, compilerOptions.downlevelIteration ? 1536 /* ExternalEmitHelpers.SpreadIncludes */ : 1024 /* ExternalEmitHelpers.SpreadArray */);