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Ban old-style type assertions under erasableSyntaxOnly #61244

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Merged
merged 6 commits into from
Feb 28, 2025
+362 −1
Merged

Ban old-style type assertions under erasableSyntaxOnly #61244

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bc7b871
Add tests
jakebailey Feb 21, 2025
6bb413d
Ban old-style type assertions as arrow function bodies under erasable…
jakebailey Feb 21, 2025
11f330a
eqeqeq
jakebailey Feb 21, 2025
14d2461
actually commit the baselines
jakebailey Feb 22, 2025
5ef765b
more test
jakebailey Feb 26, 2025
01d72c1
Ban them all
jakebailey Feb 26, 2025
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5 changes: 5 additions & 0 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -37312,6 +37312,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (file && fileExtensionIsOneOf(file.fileName, [Extension.Cts, Extension.Mts])) {
grammarErrorOnNode(node, Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Use_an_as_expression_instead);
}
if (compilerOptions.erasableSyntaxOnly) {
const start = node.type.pos - "<".length;
const end = skipTrivia(file.text, node.type.end) + ">".length;
Comment on lines +37316 to +37317
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Mentioned a different way of doing this in the pick PR, but this is probably not the right way to do this for non-syntactically correct code like

let x = <foo;

or

let y = <foo 123

diagnostics.add(createFileDiagnostic(file, start, end - start, Diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled));
}
}
return checkAssertionWorker(node, checkMode);
}
Expand Down
70 changes: 69 additions & 1 deletion tests/baselines/reference/erasableSyntaxOnly.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
error TS2318: Cannot find global type 'IterableIterator'.
commonjs.cts(1,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
commonjs.cts(2,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(3,17): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
Expand All @@ -8,9 +9,22 @@ index.ts(17,15): error TS1294: This syntax is not allowed when 'erasableSyntaxOn
index.ts(22,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(26,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(28,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(67,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(68,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(69,7): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(72,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(73,7): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(74,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(79,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(81,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(86,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(89,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(90,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
index.ts(94,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.


==== index.ts (8 errors) ====
!!! error TS2318: Cannot find global type 'IterableIterator'.
==== index.ts (20 errors) ====
class MyClassErr {
// No parameter properties
constructor(public foo: string) { }
Expand Down Expand Up @@ -92,6 +106,60 @@ index.ts(28,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOn
import FineAlias = EnumInAmbientContext.B;
}

// Not erasable
(()=><any>{})();
~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
(()=>< any >{})();
~~~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
(()=> < any > {})();
~~~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.

// Erasable
(()=><any>({}))();
~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
(()=>(<any>{}))();
~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
<any>{};
~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.


// return and yield ASI
function *gen() {
yield <any>
~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
1;
return <any>
~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
1;
}

// at the start of an ExpressionStatement if followed by an object literal; though I'm not sure why one would use it there
<unknown>{foo() {}}.foo();
~~~~~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.

// at the start of an ExpressionStatement if followed by function keyword
<unknown>function() {}();
~~~~~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
<unknown>function() {};
~~~~~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.

// at the start of an ExpressionStatement if followed by an anonymous class expression
// note that this exact syntax currently emits invalid JS (no parenthesis added like for function above)
<unknown>class {}
~~~~~~~~~
!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.

==== commonjs.cts (2 errors) ====
import foo = require("./other.cjs");
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Expand Down
88 changes: 88 additions & 0 deletions tests/baselines/reference/erasableSyntaxOnly.js
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Expand Up @@ -65,6 +65,36 @@ declare namespace AmbientStuff {

import FineAlias = EnumInAmbientContext.B;
}

// Not erasable
(()=><any>{})();
(()=>< any >{})();
(()=> < any > {})();

// Erasable
(()=><any>({}))();
(()=>(<any>{}))();
<any>{};


// return and yield ASI
function *gen() {
yield <any>
1;
return <any>
1;
}

// at the start of an ExpressionStatement if followed by an object literal; though I'm not sure why one would use it there
<unknown>{foo() {}}.foo();

// at the start of an ExpressionStatement if followed by function keyword
<unknown>function() {}();
<unknown>function() {};

// at the start of an ExpressionStatement if followed by an anonymous class expression
// note that this exact syntax currently emits invalid JS (no parenthesis added like for function above)
<unknown>class {}

//// [commonjs.cts]
import foo = require("./other.cjs");
Expand All @@ -82,6 +112,33 @@ export default foo;


//// [index.js]
var __generator = (this && this.__generator) || function (thisArg, body) {
var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g = Object.create((typeof Iterator === "function" ? Iterator : Object).prototype);
return g.next = verb(0), g["throw"] = verb(1), g["return"] = verb(2), typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
function verb(n) { return function (v) { return step([n, v]); }; }
function step(op) {
if (f) throw new TypeError("Generator is already executing.");
while (g && (g = 0, op[0] && (_ = 0)), _) try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [op[0] & 2, t.value];
switch (op[0]) {
case 0: case 1: t = op; break;
case 4: _.label++; return { value: op[1], done: false };
case 5: _.label++; y = op[1]; op = [0]; continue;
case 7: op = _.ops.pop(); _.trys.pop(); continue;
default:
if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
if (t[2]) _.ops.pop();
_.trys.pop(); continue;
}
op = body.call(thisArg, _);
} catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
}
};
var MyClassErr = /** @class */ (function () {
// No parameter properties
function MyClassErr(foo) {
Expand Down Expand Up @@ -120,6 +177,37 @@ var MyClassOk = /** @class */ (function () {
}
return MyClassOk;
}());
// Not erasable
(function () { return ({}); })();
(function () { return ({}); })();
(function () { return ({}); })();
// Erasable
(function () { return ({}); })();
(function () { return ({}); })();
({});
// return and yield ASI
function gen() {
return __generator(this, function (_a) {
switch (_a.label) {
case 0: return [4 /*yield*/, 1];
case 1:
_a.sent();
return [2 /*return*/, 1];
}
});
}
// at the start of an ExpressionStatement if followed by an object literal; though I'm not sure why one would use it there
({ foo: function () { } }.foo());
// at the start of an ExpressionStatement if followed by function keyword
(function () { })();
(function () { });
// at the start of an ExpressionStatement if followed by an anonymous class expression
// note that this exact syntax currently emits invalid JS (no parenthesis added like for function above)
/** @class */ (function () {
function class_1() {
}
return class_1;
}());
//// [commonjs.cjs]
"use strict";
var foo = require("./other.cjs");
Expand Down
35 changes: 35 additions & 0 deletions tests/baselines/reference/erasableSyntaxOnly.symbols
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Expand Up @@ -118,6 +118,41 @@ declare namespace AmbientStuff {
>B : Symbol(FineAlias, Decl(index.ts, 58, 31))
}

// Not erasable
(()=><any>{})();
(()=>< any >{})();
(()=> < any > {})();

// Erasable
(()=><any>({}))();
(()=>(<any>{}))();
<any>{};


// return and yield ASI
function *gen() {
>gen : Symbol(gen, Decl(index.ts, 73, 8))

yield <any>
1;
return <any>
1;
}

// at the start of an ExpressionStatement if followed by an object literal; though I'm not sure why one would use it there
<unknown>{foo() {}}.foo();
>{foo() {}}.foo : Symbol(foo, Decl(index.ts, 85, 10))
>foo : Symbol(foo, Decl(index.ts, 85, 10))
>foo : Symbol(foo, Decl(index.ts, 85, 10))

// at the start of an ExpressionStatement if followed by function keyword
<unknown>function() {}();
<unknown>function() {};

// at the start of an ExpressionStatement if followed by an anonymous class expression
// note that this exact syntax currently emits invalid JS (no parenthesis added like for function above)
<unknown>class {}

=== commonjs.cts ===
import foo = require("./other.cjs");
>foo : Symbol(foo, Decl(commonjs.cts, 0, 0))
Expand Down
135 changes: 135 additions & 0 deletions tests/baselines/reference/erasableSyntaxOnly.types
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Expand Up @@ -160,6 +160,141 @@ declare namespace AmbientStuff {
> : ^^^^^^^^^^^^^^^^^^^^^^
}

// Not erasable
(()=><any>{})();
>(()=><any>{})() : any
> : ^^^
>(()=><any>{}) : () => any
> : ^^^^^^
>()=><any>{} : () => any
> : ^^^^^^
><any>{} : any
> : ^^^
>{} : {}
> : ^^

(()=>< any >{})();
>(()=>< any >{})() : any
> : ^^^
>(()=>< any >{}) : () => any
> : ^^^^^^
>()=>< any >{} : () => any
> : ^^^^^^
>< any >{} : any
> : ^^^
>{} : {}
> : ^^

(()=> < any > {})();
>(()=> < any > {})() : any
> : ^^^
>(()=> < any > {}) : () => any
> : ^^^^^^
>()=> < any > {} : () => any
> : ^^^^^^
>< any > {} : any
> : ^^^
>{} : {}
> : ^^

// Erasable
(()=><any>({}))();
>(()=><any>({}))() : any
> : ^^^
>(()=><any>({})) : () => any
> : ^^^^^^
>()=><any>({}) : () => any
> : ^^^^^^
><any>({}) : any
> : ^^^
>({}) : {}
> : ^^
>{} : {}
> : ^^

(()=>(<any>{}))();
>(()=>(<any>{}))() : any
> : ^^^
>(()=>(<any>{})) : () => any
> : ^^^^^^^^^
>()=>(<any>{}) : () => any
> : ^^^^^^^^^
>(<any>{}) : any
> : ^^^
><any>{} : any
> : ^^^
>{} : {}
> : ^^

<any>{};
><any>{} : any
> : ^^^
>{} : {}
> : ^^


// return and yield ASI
function *gen() {
>gen : () => {}
> : ^^^^^^^^

yield <any>
>yield <any> 1 : any
> : ^^^
><any> 1 : any
> : ^^^

1;
>1 : 1
> : ^

return <any>
><any> 1 : any
> : ^^^

1;
>1 : 1
> : ^
}

// at the start of an ExpressionStatement if followed by an object literal; though I'm not sure why one would use it there
<unknown>{foo() {}}.foo();
><unknown>{foo() {}}.foo() : unknown
> : ^^^^^^^
>{foo() {}}.foo() : void
> : ^^^^
>{foo() {}}.foo : () => void
> : ^^^^^^^^^^
>{foo() {}} : { foo(): void; }
> : ^^^^^^^^^^^^^^^^
>foo : () => void
> : ^^^^^^^^^^
>foo : () => void
> : ^^^^^^^^^^

// at the start of an ExpressionStatement if followed by function keyword
<unknown>function() {}();
><unknown>function() {}() : unknown
> : ^^^^^^^
>function() {}() : void
> : ^^^^
>function() {} : () => void
> : ^^^^^^^^^^

<unknown>function() {};
><unknown>function() {} : unknown
> : ^^^^^^^
>function() {} : () => void
> : ^^^^^^^^^^

// at the start of an ExpressionStatement if followed by an anonymous class expression
// note that this exact syntax currently emits invalid JS (no parenthesis added like for function above)
<unknown>class {}
><unknown>class {} : unknown
> : ^^^^^^^
>class {} : typeof (Anonymous class)
> : ^^^^^^^^^^^^^^^^^^^^^^^^

=== commonjs.cts ===
import foo = require("./other.cjs");
>foo : () => void
Expand Down
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