Merge pull request #10234 from Microsoft/correct-this-in-tuple-type-parameter-constraints

Correct this in tuple type parameter constraints

src/compiler/checker.ts

@@ -1538,8 +1538,8 @@ namespace ts {
 
         function createType(flags: TypeFlags): Type {
             const result = new Type(checker, flags);
-            result.id = typeCount;
             typeCount++;
+            result.id = typeCount;
             return result;
         }
 
@@ -4000,6 +4000,9 @@ namespace ts {
                 return createTypeReference((<TypeReference>type).target,
                     concatenate((<TypeReference>type).typeArguments, [thisArgument || (<TypeReference>type).target.thisType]));
             }
+            if (type.flags & TypeFlags.Tuple) {
+                return createTupleType((type as TupleType).elementTypes, thisArgument);
+            }
             return type;
         }
 
@@ -4103,7 +4106,8 @@ namespace ts {
         function resolveTupleTypeMembers(type: TupleType) {
             const arrayElementType = getUnionType(type.elementTypes);
             // Make the tuple type itself the 'this' type by including an extra type argument
-            const arrayType = resolveStructuredTypeMembers(createTypeFromGenericGlobalType(globalArrayType, [arrayElementType, type]));
+            // (Unless it's provided in the case that the tuple is a type parameter constraint)
+            const arrayType = resolveStructuredTypeMembers(createTypeFromGenericGlobalType(globalArrayType, [arrayElementType, type.thisType || type]));
             const members = createTupleTypeMemberSymbols(type.elementTypes);
             addInheritedMembers(members, arrayType.properties);
             setObjectTypeMembers(type, members, arrayType.callSignatures, arrayType.constructSignatures, arrayType.stringIndexInfo, arrayType.numberIndexInfo);
@@ -5230,15 +5234,16 @@ namespace ts {
             return links.resolvedType;
         }
 
-        function createTupleType(elementTypes: Type[]) {
-            const id = getTypeListId(elementTypes);
-            return tupleTypes[id] || (tupleTypes[id] = createNewTupleType(elementTypes));
+        function createTupleType(elementTypes: Type[], thisType?: Type) {
+            const id = getTypeListId(elementTypes) + "," + (thisType ? thisType.id : 0);
+            return tupleTypes[id] || (tupleTypes[id] = createNewTupleType(elementTypes, thisType));
         }
 
-        function createNewTupleType(elementTypes: Type[]) {
+        function createNewTupleType(elementTypes: Type[], thisType?: Type) {
             const propagatedFlags = getPropagatingFlagsOfTypes(elementTypes, /*excludeKinds*/ 0);
             const type = <TupleType>createObjectType(TypeFlags.Tuple | propagatedFlags);
             type.elementTypes = elementTypes;
+            type.thisType = thisType;
             return type;
         }
 

src/compiler/types.ts

@@ -2371,6 +2371,7 @@ namespace ts {
 
     export interface TupleType extends ObjectType {
         elementTypes: Type[];  // Element types
+        thisType?: Type;       // This-type of tuple (only needed for tuples that are constraints of type parameters)
     }
 
     export interface UnionOrIntersectionType extends Type {

tests/baselines/reference/thisInTupleTypeParameterConstraints.js

@@ -0,0 +1,29 @@
+//// [thisInTupleTypeParameterConstraints.ts]
+/// <reference no-default-lib="true"/>
+
+interface Boolean {}
+interface IArguments {}
+interface Function {}
+interface Number {}
+interface RegExp {}
+interface Object {}
+interface String {}
+
+interface Array<T> {
+    // 4 methods will run out of memory if this-types are not instantiated
+    // correctly for tuple types that are type parameter constraints
+    map<U>(arg: this): void;
+    reduceRight<U>(arg: this): void;
+    reduce<U>(arg: this): void;
+    reduce2<U>(arg: this): void;
+}
+
+declare function f<T extends [(x: number) => number]>(a: T): void;
+let x: [(x: number) => number];
+f(x);
+
+
+//// [thisInTupleTypeParameterConstraints.js]
+/// <reference no-default-lib="true"/>
+var x;
+f(x);

tests/baselines/reference/thisInTupleTypeParameterConstraints.symbols

@@ -0,0 +1,66 @@
+=== tests/cases/compiler/thisInTupleTypeParameterConstraints.ts ===
+/// <reference no-default-lib="true"/>
+
+interface Boolean {}
+>Boolean : Symbol(Boolean, Decl(thisInTupleTypeParameterConstraints.ts, 0, 0))
+
+interface IArguments {}
+>IArguments : Symbol(IArguments, Decl(thisInTupleTypeParameterConstraints.ts, 2, 20))
+
+interface Function {}
+>Function : Symbol(Function, Decl(thisInTupleTypeParameterConstraints.ts, 3, 23))
+
+interface Number {}
+>Number : Symbol(Number, Decl(thisInTupleTypeParameterConstraints.ts, 4, 21))
+
+interface RegExp {}
+>RegExp : Symbol(RegExp, Decl(thisInTupleTypeParameterConstraints.ts, 5, 19))
+
+interface Object {}
+>Object : Symbol(Object, Decl(thisInTupleTypeParameterConstraints.ts, 6, 19))
+
+interface String {}
+>String : Symbol(String, Decl(thisInTupleTypeParameterConstraints.ts, 7, 19))
+
+interface Array<T> {
+>Array : Symbol(Array, Decl(thisInTupleTypeParameterConstraints.ts, 8, 19))
+>T : Symbol(T, Decl(thisInTupleTypeParameterConstraints.ts, 10, 16))
+
+    // 4 methods will run out of memory if this-types are not instantiated
+    // correctly for tuple types that are type parameter constraints
+    map<U>(arg: this): void;
+>map : Symbol(Array.map, Decl(thisInTupleTypeParameterConstraints.ts, 10, 20))
+>U : Symbol(U, Decl(thisInTupleTypeParameterConstraints.ts, 13, 8))
+>arg : Symbol(arg, Decl(thisInTupleTypeParameterConstraints.ts, 13, 11))
+
+    reduceRight<U>(arg: this): void;
+>reduceRight : Symbol(Array.reduceRight, Decl(thisInTupleTypeParameterConstraints.ts, 13, 28))
+>U : Symbol(U, Decl(thisInTupleTypeParameterConstraints.ts, 14, 16))
+>arg : Symbol(arg, Decl(thisInTupleTypeParameterConstraints.ts, 14, 19))
+
+    reduce<U>(arg: this): void;
+>reduce : Symbol(Array.reduce, Decl(thisInTupleTypeParameterConstraints.ts, 14, 36))
+>U : Symbol(U, Decl(thisInTupleTypeParameterConstraints.ts, 15, 11))
+>arg : Symbol(arg, Decl(thisInTupleTypeParameterConstraints.ts, 15, 14))
+
+    reduce2<U>(arg: this): void;
+>reduce2 : Symbol(Array.reduce2, Decl(thisInTupleTypeParameterConstraints.ts, 15, 31))
+>U : Symbol(U, Decl(thisInTupleTypeParameterConstraints.ts, 16, 12))
+>arg : Symbol(arg, Decl(thisInTupleTypeParameterConstraints.ts, 16, 15))
+}
+
+declare function f<T extends [(x: number) => number]>(a: T): void;
+>f : Symbol(f, Decl(thisInTupleTypeParameterConstraints.ts, 17, 1))
+>T : Symbol(T, Decl(thisInTupleTypeParameterConstraints.ts, 19, 19))
+>x : Symbol(x, Decl(thisInTupleTypeParameterConstraints.ts, 19, 31))
+>a : Symbol(a, Decl(thisInTupleTypeParameterConstraints.ts, 19, 54))
+>T : Symbol(T, Decl(thisInTupleTypeParameterConstraints.ts, 19, 19))
+
+let x: [(x: number) => number];
+>x : Symbol(x, Decl(thisInTupleTypeParameterConstraints.ts, 20, 3))
+>x : Symbol(x, Decl(thisInTupleTypeParameterConstraints.ts, 20, 9))
+
+f(x);
+>f : Symbol(f, Decl(thisInTupleTypeParameterConstraints.ts, 17, 1))
+>x : Symbol(x, Decl(thisInTupleTypeParameterConstraints.ts, 20, 3))
+

tests/baselines/reference/thisInTupleTypeParameterConstraints.types

@@ -0,0 +1,67 @@
+=== tests/cases/compiler/thisInTupleTypeParameterConstraints.ts ===
+/// <reference no-default-lib="true"/>
+
+interface Boolean {}
+>Boolean : Boolean
+
+interface IArguments {}
+>IArguments : IArguments
+
+interface Function {}
+>Function : Function
+
+interface Number {}
+>Number : Number
+
+interface RegExp {}
+>RegExp : RegExp
+
+interface Object {}
+>Object : Object
+
+interface String {}
+>String : String
+
+interface Array<T> {
+>Array : T[]
+>T : T
+
+    // 4 methods will run out of memory if this-types are not instantiated
+    // correctly for tuple types that are type parameter constraints
+    map<U>(arg: this): void;
+>map : <U>(arg: this) => void
+>U : U
+>arg : this
+
+    reduceRight<U>(arg: this): void;
+>reduceRight : <U>(arg: this) => void
+>U : U
+>arg : this
+
+    reduce<U>(arg: this): void;
+>reduce : <U>(arg: this) => void
+>U : U
+>arg : this
+
+    reduce2<U>(arg: this): void;
+>reduce2 : <U>(arg: this) => void
+>U : U
+>arg : this
+}
+
+declare function f<T extends [(x: number) => number]>(a: T): void;
+>f : <T extends [(x: number) => number]>(a: T) => void
+>T : T
+>x : number
+>a : T
+>T : T
+
+let x: [(x: number) => number];
+>x : [(x: number) => number]
+>x : number
+
+f(x);
+>f(x) : void
+>f : <T extends [(x: number) => number]>(a: T) => void
+>x : [(x: number) => number]
+

tests/cases/compiler/thisInTupleTypeParameterConstraints.ts

@@ -0,0 +1,22 @@
+/// <reference no-default-lib="true"/>
+
+interface Boolean {}
+interface IArguments {}
+interface Function {}
+interface Number {}
+interface RegExp {}
+interface Object {}
+interface String {}
+
+interface Array<T> {
+    // 4 methods will run out of memory if this-types are not instantiated
+    // correctly for tuple types that are type parameter constraints
+    map<U>(arg: this): void;
+    reduceRight<U>(arg: this): void;
+    reduce<U>(arg: this): void;
+    reduce2<U>(arg: this): void;
+}
+
+declare function f<T extends [(x: number) => number]>(a: T): void;
+let x: [(x: number) => number];
+f(x);