Tuples in rest parameters and spread expressions

package.json

@@ -47,7 +47,7 @@
         "@types/minimatch": "latest",
         "@types/minimist": "latest",
         "@types/mkdirp": "latest",
-        "@types/mocha": "latest",
+        "@types/mocha": "^5.2.2",
         "@types/node": "8.5.5",
         "@types/q": "latest",
         "@types/run-sequence": "latest",

src/compiler/binder.ts

@@ -3606,6 +3606,8 @@ namespace ts {
             case SyntaxKind.TypeLiteral:
             case SyntaxKind.ArrayType:
             case SyntaxKind.TupleType:
+            case SyntaxKind.OptionalType:
+            case SyntaxKind.RestType:
             case SyntaxKind.UnionType:
             case SyntaxKind.IntersectionType:
             case SyntaxKind.ConditionalType:

src/compiler/diagnosticMessages.json

@@ -367,10 +367,6 @@
         "category": "Error",
         "code": 1121
     },
-    "A tuple type element list cannot be empty.": {
-        "category": "Error",
-        "code": 1122
-    },
     "Variable declaration list cannot be empty.": {
         "category": "Error",
         "code": 1123
@@ -847,6 +843,14 @@
         "category": "Error",
         "code": 1255
     },
+    "A rest element must be last in a tuple type.": {
+        "category": "Error",
+        "code": 1256
+    },
+    "A required element cannot follow an optional element.": {
+        "category": "Error",
+        "code": 1257
+    },
     "'with' statements are not allowed in an async function block.": {
         "category": "Error",
         "code": 1300
@@ -2032,6 +2036,18 @@
         "category": "Error",
         "code": 2571
     },
+    "Rest signatures are incompatible.": {
+        "category": "Error",
+        "code": 2572
+    },
+    "Property '{0}' is incompatible with rest element type.": {
+        "category": "Error",
+        "code": 2573
+    },
+    "A rest element type must be an array type.": {
+        "category": "Error",
+        "code": 2574
+    },
     "JSX element attributes type '{0}' may not be a union type.": {
         "category": "Error",
         "code": 2600

src/compiler/emitter.ts

@@ -659,6 +659,8 @@ namespace ts {
                         return emitArrayType(<ArrayTypeNode>node);
                     case SyntaxKind.TupleType:
                         return emitTupleType(<TupleTypeNode>node);
+                    case SyntaxKind.OptionalType:
+                        return emitOptionalType(<OptionalTypeNode>node);
                     case SyntaxKind.UnionType:
                         return emitUnionType(<UnionTypeNode>node);
                     case SyntaxKind.IntersectionType:
@@ -695,8 +697,9 @@ namespace ts {
                         return emitJSDocNonNullableType(node as JSDocNonNullableType);
                     case SyntaxKind.JSDocOptionalType:
                         return emitJSDocOptionalType(node as JSDocOptionalType);
+                    case SyntaxKind.RestType:
                     case SyntaxKind.JSDocVariadicType:
-                        return emitJSDocVariadicType(node as JSDocVariadicType);
+                        return emitRestOrJSDocVariadicType(node as RestTypeNode | JSDocVariadicType);
 
                     // Binding patterns
                     case SyntaxKind.ObjectBindingPattern:
@@ -1304,7 +1307,7 @@ namespace ts {
             writePunctuation("]");
         }
 
-        function emitJSDocVariadicType(node: JSDocVariadicType) {
+        function emitRestOrJSDocVariadicType(node: RestTypeNode | JSDocVariadicType) {
             write("...");
             emit(node.type);
         }
@@ -1315,6 +1318,11 @@ namespace ts {
             writePunctuation("]");
         }
 
+        function emitOptionalType(node: OptionalTypeNode) {
+            emit(node.type);
+            write("?");
+        }
+
         function emitUnionType(node: UnionTypeNode) {
             emitList(node, node.types, ListFormat.UnionTypeConstituents);
         }

src/compiler/factory.ts

@@ -745,12 +745,36 @@ namespace ts {
         return node;
     }
 
-    export function updateTypleTypeNode(node: TupleTypeNode, elementTypes: ReadonlyArray<TypeNode>) {
+    export function updateTupleTypeNode(node: TupleTypeNode, elementTypes: ReadonlyArray<TypeNode>) {
         return node.elementTypes !== elementTypes
             ? updateNode(createTupleTypeNode(elementTypes), node)
             : node;
     }
 
+    export function createOptionalTypeNode(type: TypeNode) {
+        const node = createSynthesizedNode(SyntaxKind.OptionalType) as OptionalTypeNode;
+        node.type = parenthesizeArrayTypeMember(type);
+        return node;
+    }
+
+    export function updateOptionalTypeNode(node: OptionalTypeNode, type: TypeNode): OptionalTypeNode {
+        return node.type !== type
+            ? updateNode(createOptionalTypeNode(type), node)
+            : node;
+    }
+
+    export function createRestTypeNode(type: TypeNode) {
+        const node = createSynthesizedNode(SyntaxKind.RestType) as RestTypeNode;
+        node.type = type;
+        return node;
+    }
+
+    export function updateRestTypeNode(node: RestTypeNode, type: TypeNode): RestTypeNode {
+        return node.type !== type
+            ? updateNode(createRestTypeNode(type), node)
+            : node;
+    }
+
     export function createUnionTypeNode(types: ReadonlyArray<TypeNode>): UnionTypeNode {
         return <UnionTypeNode>createUnionOrIntersectionTypeNode(SyntaxKind.UnionType, types);
     }

src/compiler/parser.ts

@@ -445,19 +445,17 @@ namespace ts {
             case SyntaxKind.JsxClosingElement:
                 return visitNode(cbNode, (<JsxClosingElement>node).tagName);
 
+            case SyntaxKind.OptionalType:
+            case SyntaxKind.RestType:
             case SyntaxKind.JSDocTypeExpression:
-                return visitNode(cbNode, (<JSDocTypeExpression>node).type);
             case SyntaxKind.JSDocNonNullableType:
-                return visitNode(cbNode, (<JSDocNonNullableType>node).type);
             case SyntaxKind.JSDocNullableType:
-                return visitNode(cbNode, (<JSDocNullableType>node).type);
             case SyntaxKind.JSDocOptionalType:
-                return visitNode(cbNode, (<JSDocOptionalType>node).type);
+            case SyntaxKind.JSDocVariadicType:
+                return visitNode(cbNode, (<OptionalTypeNode | RestTypeNode | JSDocTypeExpression | JSDocTypeReferencingNode>node).type);
             case SyntaxKind.JSDocFunctionType:
                 return visitNodes(cbNode, cbNodes, (<JSDocFunctionType>node).parameters) ||
                     visitNode(cbNode, (<JSDocFunctionType>node).type);
-            case SyntaxKind.JSDocVariadicType:
-                return visitNode(cbNode, (<JSDocVariadicType>node).type);
             case SyntaxKind.JSDocComment:
                 return visitNodes(cbNode, cbNodes, (<JSDoc>node).tags);
             case SyntaxKind.JSDocParameterTag:
@@ -2293,7 +2291,7 @@ namespace ts {
         function parseJSDocAllType(postFixEquals: boolean): JSDocAllType | JSDocOptionalType {
             const result = createNode(SyntaxKind.JSDocAllType) as JSDocAllType;
             if (postFixEquals) {
-                return createJSDocPostfixType(SyntaxKind.JSDocOptionalType, result) as JSDocOptionalType;
+                return createPostfixType(SyntaxKind.JSDocOptionalType, result) as JSDocOptionalType;
             }
             else {
                 nextToken();
@@ -2371,7 +2369,7 @@ namespace ts {
                 type = finishNode(variadic);
             }
             if (token() === SyntaxKind.EqualsToken) {
-                return createJSDocPostfixType(SyntaxKind.JSDocOptionalType, type);
+                return createPostfixType(SyntaxKind.JSDocOptionalType, type);
             }
             return type;
         }
@@ -2779,9 +2777,23 @@ namespace ts {
             return finishNode(node);
         }
 
+        function parseTupleElementType() {
+            const pos = getNodePos();
+            if (parseOptional(SyntaxKind.DotDotDotToken)) {
+                const node = <RestTypeNode>createNode(SyntaxKind.RestType, pos);
+                node.type = parseType();
+                return finishNode(node);
+            }
+            const type = parseType();
+            if (!(contextFlags & NodeFlags.JSDoc) && type.kind === SyntaxKind.JSDocNullableType && type.pos === (<JSDocNullableType>type).type.pos) {
+                type.kind = SyntaxKind.OptionalType;
+            }
+            return type;
+        }
+
         function parseTupleType(): TupleTypeNode {
             const node = <TupleTypeNode>createNode(SyntaxKind.TupleType);
-            node.elementTypes = parseBracketedList(ParsingContext.TupleElementTypes, parseType, SyntaxKind.OpenBracketToken, SyntaxKind.CloseBracketToken);
+            node.elementTypes = parseBracketedList(ParsingContext.TupleElementTypes, parseTupleElementType, SyntaxKind.OpenBracketToken, SyntaxKind.CloseBracketToken);
             return finishNode(node);
         }
 
@@ -2964,14 +2976,14 @@ namespace ts {
             while (!scanner.hasPrecedingLineBreak()) {
                 switch (token()) {
                     case SyntaxKind.ExclamationToken:
-                        type = createJSDocPostfixType(SyntaxKind.JSDocNonNullableType, type);
+                        type = createPostfixType(SyntaxKind.JSDocNonNullableType, type);
                         break;
                     case SyntaxKind.QuestionToken:
                         // If not in JSDoc and next token is start of a type we have a conditional type
                         if (!(contextFlags & NodeFlags.JSDoc) && lookAhead(nextTokenIsStartOfType)) {
                             return type;
                         }
-                        type = createJSDocPostfixType(SyntaxKind.JSDocNullableType, type);
+                        type = createPostfixType(SyntaxKind.JSDocNullableType, type);
                         break;
                     case SyntaxKind.OpenBracketToken:
                         parseExpected(SyntaxKind.OpenBracketToken);
@@ -2996,9 +3008,9 @@ namespace ts {
             return type;
         }
 
-        function createJSDocPostfixType(kind: SyntaxKind, type: TypeNode) {
+        function createPostfixType(kind: SyntaxKind, type: TypeNode) {
             nextToken();
-            const postfix = createNode(kind, type.pos) as JSDocOptionalType | JSDocNonNullableType | JSDocNullableType;
+            const postfix = createNode(kind, type.pos) as OptionalTypeNode | JSDocOptionalType | JSDocNonNullableType | JSDocNullableType;
             postfix.type = type;
             return finishNode(postfix);
         }

src/compiler/transformers/ts.ts

@@ -380,6 +380,8 @@ namespace ts {
 
                 case SyntaxKind.ArrayType:
                 case SyntaxKind.TupleType:
+                case SyntaxKind.OptionalType:
+                case SyntaxKind.RestType:
                 case SyntaxKind.TypeLiteral:
                 case SyntaxKind.TypePredicate:
                 case SyntaxKind.TypeParameter:

src/compiler/types.ts

@@ -225,6 +225,8 @@ namespace ts {
         TypeLiteral,
         ArrayType,
         TupleType,
+        OptionalType,
+        RestType,
         UnionType,
         IntersectionType,
         ConditionalType,
@@ -269,6 +271,7 @@ namespace ts {
         AsExpression,
         NonNullExpression,
         MetaProperty,
+        SyntheticExpression,
 
         // Misc
         TemplateSpan,
@@ -1101,6 +1104,16 @@ namespace ts {
         elementTypes: NodeArray<TypeNode>;
     }
 
+    export interface OptionalTypeNode extends TypeNode {
+        kind: SyntaxKind.OptionalType;
+        type: TypeNode;
+    }
+
+    export interface RestTypeNode extends TypeNode {
+        kind: SyntaxKind.RestType;
+        type: TypeNode;
+    }
+
     export type UnionOrIntersectionTypeNode = UnionTypeNode | IntersectionTypeNode;
 
     export interface UnionTypeNode extends TypeNode {
@@ -1288,6 +1301,12 @@ namespace ts {
         expression?: Expression;
     }
 
+    export interface SyntheticExpression extends Expression {
+        kind: SyntaxKind.SyntheticExpression;
+        isSpread: boolean;
+        type: Type;
+    }
+
     // see: https://tc39.github.io/ecma262/#prod-ExponentiationExpression
     export type ExponentiationOperator
         = SyntaxKind.AsteriskAsteriskToken
@@ -3520,14 +3539,15 @@ namespace ts {
         ContainsPrivate   = 1 << 8,         // Synthetic property with private constituent(s)
         ContainsStatic    = 1 << 9,         // Synthetic property with static constituent(s)
         Late              = 1 << 10,        // Late-bound symbol for a computed property with a dynamic name
-        ReverseMapped     = 1 << 11,        // property of reverse-inferred homomorphic mapped type.
+        ReverseMapped     = 1 << 11,        // Property of reverse-inferred homomorphic mapped type
+        OptionalParameter = 1 << 12,        // Optional parameter
+        RestParameter     = 1 << 13,        // Rest parameter
         Synthetic = SyntheticProperty | SyntheticMethod
     }
 
     /* @internal */
     export interface TransientSymbol extends Symbol, SymbolLinks {
         checkFlags: CheckFlags;
-        isRestParameter?: boolean;
     }
 
     /* @internal */
@@ -3856,6 +3876,16 @@ namespace ts {
         variances?: Variance[];  // Variance of each type parameter
     }
 
+    export interface TupleType extends GenericType {
+        minLength: number;
+        hasRestElement: boolean;
+        associatedNames?: __String[];
+    }
+
+    export interface TupleTypeReference extends TypeReference {
+        target: TupleType;
+    }
+
     export interface UnionOrIntersectionType extends Type {
         types: Type[];                    // Constituent types
         /* @internal */

src/compiler/visitor.ts

@@ -372,9 +372,17 @@ namespace ts {
                     visitNode((<ArrayTypeNode>node).elementType, visitor, isTypeNode));
 
             case SyntaxKind.TupleType:
-                return updateTypleTypeNode((<TupleTypeNode>node),
+                return updateTupleTypeNode((<TupleTypeNode>node),
                     nodesVisitor((<TupleTypeNode>node).elementTypes, visitor, isTypeNode));
 
+            case SyntaxKind.OptionalType:
+                return updateOptionalTypeNode((<OptionalTypeNode>node),
+                    visitNode((<OptionalTypeNode>node).type, visitor, isTypeNode));
+
+            case SyntaxKind.RestType:
+                return updateRestTypeNode((<RestTypeNode>node),
+                    visitNode((<RestTypeNode>node).type, visitor, isTypeNode));
+
             case SyntaxKind.UnionType:
                 return updateUnionTypeNode(<UnionTypeNode>node,
                     nodesVisitor((<UnionTypeNode>node).types, visitor, isTypeNode));

tests/baselines/reference/anyIndexedAccessArrayNoException.errors.txt

@@ -1,11 +1,8 @@
-tests/cases/compiler/anyIndexedAccessArrayNoException.ts(1,12): error TS1122: A tuple type element list cannot be empty.
 tests/cases/compiler/anyIndexedAccessArrayNoException.ts(1,12): error TS2538: Type '[]' cannot be used as an index type.
 
 
-==== tests/cases/compiler/anyIndexedAccessArrayNoException.ts (2 errors) ====
+==== tests/cases/compiler/anyIndexedAccessArrayNoException.ts (1 errors) ====
     var x: any[[]];
                ~~
-!!! error TS1122: A tuple type element list cannot be empty.
-               ~~
 !!! error TS2538: Type '[]' cannot be used as an index type.