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Merged
ahejlsberg merged 15 commits into from
Dec 16, 2022
Merged

const modifier on type parameters #51865

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bd0ce7b
`const` modifier on type parameters + revised contextual type logic
ahejlsberg Dec 12, 2022
7c48b0d
Accept new baselines
ahejlsberg Dec 12, 2022
88c7149
Fix modifier checking
ahejlsberg Dec 12, 2022
ccf252f
Add tests
ahejlsberg Dec 12, 2022
f8fd1fd
Cache isConstTypeVariable check
ahejlsberg Dec 12, 2022
c3fcf6e
Revert "Cache isConstTypeVariable check"
ahejlsberg Dec 13, 2022
0507bf0
Fewer isConstTypeParameterContext checks
ahejlsberg Dec 13, 2022
b56d187
Pay attention to cached `undefined` contextual type
ahejlsberg Dec 13, 2022
54f649d
Allow `const` modifier in more places + properly print back
ahejlsberg Dec 13, 2022
d2af941
Also permit `const` in method signature type parameters
ahejlsberg Dec 13, 2022
a315761
Fix parsing of `const` modifier in array expression type parameters
ahejlsberg Dec 13, 2022
f6bbf9c
Accept new baselines
ahejlsberg Dec 13, 2022
636d937
Merge branch 'main' into fix30680
ahejlsberg Dec 13, 2022
dccb290
Remove unused properties from NodeLinks
ahejlsberg Dec 13, 2022
fde9c47
Rename `permitInvalidConstAsModifier` to `permitConstAsModifier`
ahejlsberg Dec 15, 2022
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@ahejlsberg
ahejlsberg committed Dec 12, 2022
commit ccf252f8f3d07d90ca7d25cd62887cdc7fdf5b7a
68 changes: 68 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.errors.txt
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tests/cases/conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts(40,14): error TS1277: 'const' modifier can only appear on a type parameter of a function, method or class
tests/cases/conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts(42,9): error TS1277: 'const' modifier can only appear on a type parameter of a function, method or class


==== tests/cases/conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts (2 errors) ====
declare function f1<const T>(x: T): T;

const x11 = f1('a');
const x12 = f1(['a', ['b', 'c']]);
const x13 = f1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });

declare function f2<const T, U>(x: T | undefined): T;

const x21 = f2('a');
const x22 = f2(['a', ['b', 'c']]);
const x23 = f2({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });

declare function f3<const T>(x: T): T[];

const x31 = f3("hello");
const x32 = f3("hello");

declare function f4<const T>(obj: [T, T]): T;

const x41 = f4([[1, 'x'], [2, 'y']]);
const x42 = f4([{ a: 1, b: 'x' }, { a: 2, b: 'y' }]);

declare function f5<const T>(obj: { x: T, y: T }): T;

const x51 = f5({ x: [1, 'x'], y: [2, 'y'] });
const x52 = f5({ x: { a: 1, b: 'x' }, y: { a: 2, b: 'y' } });

declare function f6<const T extends readonly unknown[]>(...args: T): T;

const x61 = f6(1, 'b', { a: 1, b: 'x' });

class C1<const T> {
constructor(x: T) {}
foo<const U>(x: U) { return x; }
}

const c71 = new C1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
const c72 = c71.foo(['a', ['b', 'c']]);

interface I1<const T> { x: T } // Error
~~~~~
!!! error TS1277: 'const' modifier can only appear on a type parameter of a function, method or class

type T1<const T> = T; // Error
~~~~~
!!! error TS1277: 'const' modifier can only appear on a type parameter of a function, method or class

// Corrected repro from #51745

type Obj = { a: { b: { c: "123" } } };

type GetPath<T, P> =
P extends readonly [] ? T :
P extends readonly [infer A extends keyof T, ...infer Rest] ? GetPath<T[A], Rest> :
never;

function set<T, const P extends readonly string[]>(obj: T, path: P, value: GetPath<T, P>) {}

declare let obj: Obj;
declare let value: "123";

set(obj, ['a', 'b', 'c'], value);

86 changes: 86 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.js
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//// [typeParameterConstModifiers.ts]
declare function f1<const T>(x: T): T;

const x11 = f1('a');
const x12 = f1(['a', ['b', 'c']]);
const x13 = f1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });

declare function f2<const T, U>(x: T | undefined): T;

const x21 = f2('a');
const x22 = f2(['a', ['b', 'c']]);
const x23 = f2({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });

declare function f3<const T>(x: T): T[];

const x31 = f3("hello");
const x32 = f3("hello");

declare function f4<const T>(obj: [T, T]): T;

const x41 = f4([[1, 'x'], [2, 'y']]);
const x42 = f4([{ a: 1, b: 'x' }, { a: 2, b: 'y' }]);

declare function f5<const T>(obj: { x: T, y: T }): T;

const x51 = f5({ x: [1, 'x'], y: [2, 'y'] });
const x52 = f5({ x: { a: 1, b: 'x' }, y: { a: 2, b: 'y' } });

declare function f6<const T extends readonly unknown[]>(...args: T): T;

const x61 = f6(1, 'b', { a: 1, b: 'x' });

class C1<const T> {
constructor(x: T) {}
foo<const U>(x: U) { return x; }
}

const c71 = new C1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
const c72 = c71.foo(['a', ['b', 'c']]);

interface I1<const T> { x: T } // Error

type T1<const T> = T; // Error

// Corrected repro from #51745

type Obj = { a: { b: { c: "123" } } };

type GetPath<T, P> =
P extends readonly [] ? T :
P extends readonly [infer A extends keyof T, ...infer Rest] ? GetPath<T[A], Rest> :
never;

function set<T, const P extends readonly string[]>(obj: T, path: P, value: GetPath<T, P>) {}

declare let obj: Obj;
declare let value: "123";

set(obj, ['a', 'b', 'c'], value);


//// [typeParameterConstModifiers.js]
"use strict";
var x11 = f1('a');
var x12 = f1(['a', ['b', 'c']]);
var x13 = f1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
var x21 = f2('a');
var x22 = f2(['a', ['b', 'c']]);
var x23 = f2({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
var x31 = f3("hello");
var x32 = f3("hello");
var x41 = f4([[1, 'x'], [2, 'y']]);
var x42 = f4([{ a: 1, b: 'x' }, { a: 2, b: 'y' }]);
var x51 = f5({ x: [1, 'x'], y: [2, 'y'] });
var x52 = f5({ x: { a: 1, b: 'x' }, y: { a: 2, b: 'y' } });
var x61 = f6(1, 'b', { a: 1, b: 'x' });
var C1 = /** @class */ (function () {
function C1(x) {
}
C1.prototype.foo = function (x) { return x; };
return C1;
}());
var c71 = new C1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
var c72 = c71.foo(['a', ['b', 'c']]);
function set(obj, path, value) { }
set(obj, ['a', 'b', 'c'], value);
217 changes: 217 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.symbols
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=== tests/cases/conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts ===
declare function f1<const T>(x: T): T;
>f1 : Symbol(f1, Decl(typeParameterConstModifiers.ts, 0, 0))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 0, 20))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 0, 29))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 0, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 0, 20))

const x11 = f1('a');
>x11 : Symbol(x11, Decl(typeParameterConstModifiers.ts, 2, 5))
>f1 : Symbol(f1, Decl(typeParameterConstModifiers.ts, 0, 0))

const x12 = f1(['a', ['b', 'c']]);
>x12 : Symbol(x12, Decl(typeParameterConstModifiers.ts, 3, 5))
>f1 : Symbol(f1, Decl(typeParameterConstModifiers.ts, 0, 0))

const x13 = f1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
>x13 : Symbol(x13, Decl(typeParameterConstModifiers.ts, 4, 5))
>f1 : Symbol(f1, Decl(typeParameterConstModifiers.ts, 0, 0))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 4, 16))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 4, 22))
>d : Symbol(d, Decl(typeParameterConstModifiers.ts, 4, 30))
>f : Symbol(f, Decl(typeParameterConstModifiers.ts, 4, 50))

declare function f2<const T, U>(x: T | undefined): T;
>f2 : Symbol(f2, Decl(typeParameterConstModifiers.ts, 4, 64))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 6, 20))
>U : Symbol(U, Decl(typeParameterConstModifiers.ts, 6, 28))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 6, 32))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 6, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 6, 20))

const x21 = f2('a');
>x21 : Symbol(x21, Decl(typeParameterConstModifiers.ts, 8, 5))
>f2 : Symbol(f2, Decl(typeParameterConstModifiers.ts, 4, 64))

const x22 = f2(['a', ['b', 'c']]);
>x22 : Symbol(x22, Decl(typeParameterConstModifiers.ts, 9, 5))
>f2 : Symbol(f2, Decl(typeParameterConstModifiers.ts, 4, 64))

const x23 = f2({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
>x23 : Symbol(x23, Decl(typeParameterConstModifiers.ts, 10, 5))
>f2 : Symbol(f2, Decl(typeParameterConstModifiers.ts, 4, 64))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 10, 16))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 10, 22))
>d : Symbol(d, Decl(typeParameterConstModifiers.ts, 10, 30))
>f : Symbol(f, Decl(typeParameterConstModifiers.ts, 10, 50))

declare function f3<const T>(x: T): T[];
>f3 : Symbol(f3, Decl(typeParameterConstModifiers.ts, 10, 64))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 12, 20))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 12, 29))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 12, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 12, 20))

const x31 = f3("hello");
>x31 : Symbol(x31, Decl(typeParameterConstModifiers.ts, 14, 5))
>f3 : Symbol(f3, Decl(typeParameterConstModifiers.ts, 10, 64))

const x32 = f3("hello");
>x32 : Symbol(x32, Decl(typeParameterConstModifiers.ts, 15, 5))
>f3 : Symbol(f3, Decl(typeParameterConstModifiers.ts, 10, 64))

declare function f4<const T>(obj: [T, T]): T;
>f4 : Symbol(f4, Decl(typeParameterConstModifiers.ts, 15, 24))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 17, 20))
>obj : Symbol(obj, Decl(typeParameterConstModifiers.ts, 17, 29))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 17, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 17, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 17, 20))

const x41 = f4([[1, 'x'], [2, 'y']]);
>x41 : Symbol(x41, Decl(typeParameterConstModifiers.ts, 19, 5))
>f4 : Symbol(f4, Decl(typeParameterConstModifiers.ts, 15, 24))

const x42 = f4([{ a: 1, b: 'x' }, { a: 2, b: 'y' }]);
>x42 : Symbol(x42, Decl(typeParameterConstModifiers.ts, 20, 5))
>f4 : Symbol(f4, Decl(typeParameterConstModifiers.ts, 15, 24))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 20, 17))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 20, 23))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 20, 35))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 20, 41))

declare function f5<const T>(obj: { x: T, y: T }): T;
>f5 : Symbol(f5, Decl(typeParameterConstModifiers.ts, 20, 53))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 22, 20))
>obj : Symbol(obj, Decl(typeParameterConstModifiers.ts, 22, 29))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 22, 35))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 22, 20))
>y : Symbol(y, Decl(typeParameterConstModifiers.ts, 22, 41))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 22, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 22, 20))

const x51 = f5({ x: [1, 'x'], y: [2, 'y'] });
>x51 : Symbol(x51, Decl(typeParameterConstModifiers.ts, 24, 5))
>f5 : Symbol(f5, Decl(typeParameterConstModifiers.ts, 20, 53))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 24, 16))
>y : Symbol(y, Decl(typeParameterConstModifiers.ts, 24, 29))

const x52 = f5({ x: { a: 1, b: 'x' }, y: { a: 2, b: 'y' } });
>x52 : Symbol(x52, Decl(typeParameterConstModifiers.ts, 25, 5))
>f5 : Symbol(f5, Decl(typeParameterConstModifiers.ts, 20, 53))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 25, 16))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 25, 21))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 25, 27))
>y : Symbol(y, Decl(typeParameterConstModifiers.ts, 25, 37))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 25, 42))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 25, 48))

declare function f6<const T extends readonly unknown[]>(...args: T): T;
>f6 : Symbol(f6, Decl(typeParameterConstModifiers.ts, 25, 61))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 27, 20))
>args : Symbol(args, Decl(typeParameterConstModifiers.ts, 27, 56))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 27, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 27, 20))

const x61 = f6(1, 'b', { a: 1, b: 'x' });
>x61 : Symbol(x61, Decl(typeParameterConstModifiers.ts, 29, 5))
>f6 : Symbol(f6, Decl(typeParameterConstModifiers.ts, 25, 61))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 29, 24))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 29, 30))

class C1<const T> {
>C1 : Symbol(C1, Decl(typeParameterConstModifiers.ts, 29, 41))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 31, 9))

constructor(x: T) {}
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 32, 16))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 31, 9))

foo<const U>(x: U) { return x; }
>foo : Symbol(C1.foo, Decl(typeParameterConstModifiers.ts, 32, 24))
>U : Symbol(U, Decl(typeParameterConstModifiers.ts, 33, 8))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 33, 17))
>U : Symbol(U, Decl(typeParameterConstModifiers.ts, 33, 8))
>x : Symbol(x, Decl(typeParameterConstModifiers.ts, 33, 17))
}

const c71 = new C1({ a: 1, b: "c", d: ["e", 2, true, { f: "g" }] });
>c71 : Symbol(c71, Decl(typeParameterConstModifiers.ts, 36, 5))
>C1 : Symbol(C1, Decl(typeParameterConstModifiers.ts, 29, 41))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 36, 20))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 36, 26))
>d : Symbol(d, Decl(typeParameterConstModifiers.ts, 36, 34))
>f : Symbol(f, Decl(typeParameterConstModifiers.ts, 36, 54))

const c72 = c71.foo(['a', ['b', 'c']]);
>c72 : Symbol(c72, Decl(typeParameterConstModifiers.ts, 37, 5))
>c71.foo : Symbol(C1.foo, Decl(typeParameterConstModifiers.ts, 32, 24))
>c71 : Symbol(c71, Decl(typeParameterConstModifiers.ts, 36, 5))
>foo : Symbol(C1.foo, Decl(typeParameterConstModifiers.ts, 32, 24))

interface I1<const T> { x: T } // Error
>I1 : Symbol(I1, Decl(typeParameterConstModifiers.ts, 37, 39))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 39, 13))
>x : Symbol(I1.x, Decl(typeParameterConstModifiers.ts, 39, 23))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 39, 13))

type T1<const T> = T; // Error
>T1 : Symbol(T1, Decl(typeParameterConstModifiers.ts, 39, 30))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 41, 8))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 41, 8))

// Corrected repro from #51745

type Obj = { a: { b: { c: "123" } } };
>Obj : Symbol(Obj, Decl(typeParameterConstModifiers.ts, 41, 21))
>a : Symbol(a, Decl(typeParameterConstModifiers.ts, 45, 12))
>b : Symbol(b, Decl(typeParameterConstModifiers.ts, 45, 17))
>c : Symbol(c, Decl(typeParameterConstModifiers.ts, 45, 22))

type GetPath<T, P> =
>GetPath : Symbol(GetPath, Decl(typeParameterConstModifiers.ts, 45, 38))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 47, 13))
>P : Symbol(P, Decl(typeParameterConstModifiers.ts, 47, 15))

P extends readonly [] ? T :
>P : Symbol(P, Decl(typeParameterConstModifiers.ts, 47, 15))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 47, 13))

P extends readonly [infer A extends keyof T, ...infer Rest] ? GetPath<T[A], Rest> :
>P : Symbol(P, Decl(typeParameterConstModifiers.ts, 47, 15))
>A : Symbol(A, Decl(typeParameterConstModifiers.ts, 49, 29))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 47, 13))
>Rest : Symbol(Rest, Decl(typeParameterConstModifiers.ts, 49, 57))
>GetPath : Symbol(GetPath, Decl(typeParameterConstModifiers.ts, 45, 38))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 47, 13))
>A : Symbol(A, Decl(typeParameterConstModifiers.ts, 49, 29))
>Rest : Symbol(Rest, Decl(typeParameterConstModifiers.ts, 49, 57))

never;

function set<T, const P extends readonly string[]>(obj: T, path: P, value: GetPath<T, P>) {}
>set : Symbol(set, Decl(typeParameterConstModifiers.ts, 50, 10))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 52, 13))
>P : Symbol(P, Decl(typeParameterConstModifiers.ts, 52, 15))
>obj : Symbol(obj, Decl(typeParameterConstModifiers.ts, 52, 51))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 52, 13))
>path : Symbol(path, Decl(typeParameterConstModifiers.ts, 52, 58))
>P : Symbol(P, Decl(typeParameterConstModifiers.ts, 52, 15))
>value : Symbol(value, Decl(typeParameterConstModifiers.ts, 52, 67))
>GetPath : Symbol(GetPath, Decl(typeParameterConstModifiers.ts, 45, 38))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 52, 13))
>P : Symbol(P, Decl(typeParameterConstModifiers.ts, 52, 15))

declare let obj: Obj;
>obj : Symbol(obj, Decl(typeParameterConstModifiers.ts, 54, 11))
>Obj : Symbol(Obj, Decl(typeParameterConstModifiers.ts, 41, 21))

declare let value: "123";
>value : Symbol(value, Decl(typeParameterConstModifiers.ts, 55, 11))

set(obj, ['a', 'b', 'c'], value);
>set : Symbol(set, Decl(typeParameterConstModifiers.ts, 50, 10))
>obj : Symbol(obj, Decl(typeParameterConstModifiers.ts, 54, 11))
>value : Symbol(value, Decl(typeParameterConstModifiers.ts, 55, 11))

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