Function combineUnionParameters

test/fixtures/snapshot/typescript.js:58192–58232

(left, right, mapper)

            return createSymbolWithType(left, thisType);
        }
        function combineUnionParameters(left, right, mapper) {
            var leftCount = getParameterCount(left);
            var rightCount = getParameterCount(right);
            var longest = leftCount >= rightCount ? left : right;
            var shorter = longest === left ? right : left;
            var longestCount = longest === left ? leftCount : rightCount;
            var eitherHasEffectiveRest = (hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right));
            var needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest);
            var params = new Array(longestCount + (needsExtraRestElement ? 1 : 0));
            for (var i = 0; i < longestCount; i++) {
                var longestParamType = tryGetTypeAtPosition(longest, i);
                if (longest === right) {
                    longestParamType = instantiateType(longestParamType, mapper);
                }
                var shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType;
                if (shorter === right) {
                    shorterParamType = instantiateType(shorterParamType, mapper);
                }
                var unionParamType = getIntersectionType([longestParamType, shorterParamType]);
                var isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1);
                var isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter);
                var leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i);
                var rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i);
                var paramName = leftName === rightName ? leftName :
                    !leftName ? rightName :
                        !rightName ? leftName :
                            undefined;
                var paramSymbol = createSymbol(1 /* SymbolFlags.FunctionScopedVariable */ | (isOptional && !isRestParam ? 16777216 /* SymbolFlags.Optional */ : 0), paramName || "arg".concat(i));
                paramSymbol.type = isRestParam ? createArrayType(unionParamType) : unionParamType;
                params[i] = paramSymbol;
            }
            if (needsExtraRestElement) {
                var restParamSymbol = createSymbol(1 /* SymbolFlags.FunctionScopedVariable */, "args");
                restParamSymbol.type = createArrayType(getTypeAtPosition(shorter, longestCount));
                if (shorter === right) {
                    restParamSymbol.type = instantiateType(restParamSymbol.type, mapper);
                }
                params[longestCount] = restParamSymbol;
            }
            return params;
        }
        function combineSignaturesOfUnionMembers(left, right) {
            var typeParams = left.typeParameters || right.typeParameters;
            var paramMapper;