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Fix #62179: Restrict import attribute values to string literals #62638

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Fix #62179: Restrict import attribute values to string literals #62638

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ae81b7f
Fix #62179: Restrict import attribute values to string literals
sdotson Oct 20, 2025
97d864d
rethink things to improve error messages/
sdotson Oct 20, 2025
784aacb
actually do something now
sdotson Oct 20, 2025
f80cada
Validate import attribute values before type checking to avoid perfor…
sdotson Oct 21, 2025
58da68f
remove unused file
sdotson Oct 21, 2025
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2 changes: 1 addition & 1 deletion src/compiler/parser.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8444,7 +8444,7 @@ namespace Parser {
const pos = getNodePos();
const name = tokenIsIdentifierOrKeyword(token()) ? parseIdentifierName() : parseLiteralLikeNode(SyntaxKind.StringLiteral) as StringLiteral;
parseExpected(SyntaxKind.ColonToken);
const value = parseAssignmentExpressionOrHigher(/*allowReturnTypeInArrowFunction*/ true);
const value = parseLiteralLikeNode(SyntaxKind.StringLiteral) as StringLiteral;
return finishNode(factory.createImportAttribute(name, value), pos);
}

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124 changes: 60 additions & 64 deletions tests/baselines/reference/importAssertionNonstring.errors.txt
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@@ -1,78 +1,74 @@
mod.mts(1,37): error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
mod.mts(1,37): error TS2322: Type '{ field: 0; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type 'number' is not assignable to type 'string'.
mod.mts(1,52): error TS2837: Import assertion values must be string literal expressions.
mod.mts(3,37): error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
mod.mts(3,52): error TS2837: Import assertion values must be string literal expressions.
mod.mts(5,37): error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
mod.mts(5,37): error TS2322: Type '{ field: RegExp; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type 'RegExp' is not assignable to type 'string'.
mod.mts(5,52): error TS2837: Import assertion values must be string literal expressions.
mod.mts(7,37): error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
mod.mts(7,37): error TS2322: Type '{ field: string[]; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type 'string[]' is not assignable to type 'string'.
mod.mts(7,52): error TS2837: Import assertion values must be string literal expressions.
mod.mts(9,37): error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
mod.mts(9,37): error TS2322: Type '{ field: { a: number; }; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type '{ a: number; }' is not assignable to type 'string'.
mod.mts(9,52): error TS2837: Import assertion values must be string literal expressions.
mod.mts(11,37): error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
mod.mts(11,66): error TS2837: Import assertion values must be string literal expressions.
mod.mts(5,53): error TS1005: ',' expected.
mod.mts(5,54): error TS1005: ':' expected.
mod.mts(5,55): error TS1005: ',' expected.
mod.mts(5,56): error TS1005: ':' expected.
mod.mts(5,57): error TS1005: ',' expected.
mod.mts(7,8): error TS1005: ':' expected.
mod.mts(7,10): error TS1005: ',' expected.
mod.mts(7,13): error TS1005: ':' expected.
mod.mts(7,20): error TS1005: ',' expected.
mod.mts(7,25): error TS1005: ':' expected.
mod.mts(7,37): error TS1005: ',' expected.
mod.mts(7,44): error TS1005: ':' expected.
mod.mts(7,45): error TS1005: ',' expected.
mod.mts(7,53): error TS1005: ',' expected.
mod.mts(7,56): error TS1005: ':' expected.
mod.mts(9,54): error TS1005: ',' expected.
mod.mts(9,60): error TS1128: Declaration or statement expected.
mod.mts(11,68): error TS1005: ',' expected.
mod.mts(11,77): error TS1005: ':' expected.
mod.mts(11,78): error TS1005: ',' expected.


==== mod.mts (16 errors) ====
==== mod.mts (20 errors) ====
import * as thing1 from "./mod.mjs" assert {field: 0};
~~~~~~
!!! error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: 0; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
~
!!! error TS2837: Import assertion values must be string literal expressions.

import * as thing2 from "./mod.mjs" assert {field: `a`};
~~~~~~
!!! error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
~~~
!!! error TS2837: Import assertion values must be string literal expressions.

import * as thing3 from "./mod.mjs" assert {field: /a/g};
~~~~~~
!!! error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
~~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: RegExp; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type 'RegExp' is not assignable to type 'string'.
~~~~
!!! error TS2837: Import assertion values must be string literal expressions.
~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~
!!! error TS1005: ',' expected.

import * as thing4 from "./mod.mjs" assert {field: ["a"]};
~
!!! error TS1005: ':' expected.
~~
!!! error TS1005: ',' expected.
~~~~~~
!!! error TS1005: ':' expected.
~~~~
!!! error TS1005: ',' expected.
~~~~~~~~~~~
!!! error TS1005: ':' expected.
~~~~~~
!!! error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
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The error messages in this test are much worse now

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I think they should be better now. Thank you for the review.

~~~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: string[]; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type 'string[]' is not assignable to type 'string'.
~~~~~
!!! error TS2837: Import assertion values must be string literal expressions.
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~~~~~
!!! error TS1005: ',' expected.
~~~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.

import * as thing5 from "./mod.mjs" assert {field: { a: 0 }};
~~~~~~
!!! error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: { a: number; }; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type '{ a: number; }' is not assignable to type 'string'.
~~~~~~~~
!!! error TS2837: Import assertion values must be string literal expressions.
~
!!! error TS1005: ',' expected.
~
!!! error TS1128: Declaration or statement expected.

import * as thing6 from "./mod.mjs" assert {type: "json", field: 0..toString()}
~~~~~~
!!! error TS2880: Import assertions have been replaced by import attributes. Use 'with' instead of 'assert'.
~~~~~~~~~~~~~
!!! error TS2837: Import assertion values must be string literal expressions.
~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~
!!! error TS1005: ',' expected.
1 change: 1 addition & 0 deletions tests/baselines/reference/importAssertionNonstring.js
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Expand Up @@ -14,4 +14,5 @@ import * as thing5 from "./mod.mjs" assert {field: { a: 0 }};
import * as thing6 from "./mod.mjs" assert {type: "json", field: 0..toString()}

//// [mod.mjs]
;
export {};
4 changes: 0 additions & 4 deletions tests/baselines/reference/importAssertionNonstring.symbols
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Expand Up @@ -11,14 +11,10 @@ import * as thing3 from "./mod.mjs" assert {field: /a/g};
>thing3 : Symbol(thing3, Decl(mod.mts, 4, 6))

import * as thing4 from "./mod.mjs" assert {field: ["a"]};
>thing4 : Symbol(thing4, Decl(mod.mts, 6, 6))

import * as thing5 from "./mod.mjs" assert {field: { a: 0 }};
>thing5 : Symbol(thing5, Decl(mod.mts, 8, 6))
>a : Symbol(a, Decl(mod.mts, 8, 52))

import * as thing6 from "./mod.mjs" assert {type: "json", field: 0..toString()}
>thing6 : Symbol(thing6, Decl(mod.mts, 10, 6))
>0..toString : Symbol(Number.toString, Decl(lib.es5.d.ts, --, --))
>toString : Symbol(Number.toString, Decl(lib.es5.d.ts, --, --))

38 changes: 16 additions & 22 deletions tests/baselines/reference/importAssertionNonstring.types
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Expand Up @@ -18,30 +18,30 @@ import * as thing3 from "./mod.mjs" assert {field: /a/g};
> : ^^^^^^^^^^^^^
>field : any
> : ^^^
>/a/g : RegExp
> : ^^^^^^
>a : any
> : ^^^
>g : any
> : ^^^

import * as thing4 from "./mod.mjs" assert {field: ["a"]};
>thing4 : typeof thing1
> : ^^^^^^^^^^^^^
>import : any
> : ^^^
>as : any
> : ^^^
>from : any
> : ^^^
>assert : any
> : ^^^
>field : any
> : ^^^
>["a"] : string[]
> : ^^^^^^^^
>"a" : "a"
> : ^^^

import * as thing5 from "./mod.mjs" assert {field: { a: 0 }};
>thing5 : typeof thing1
> : ^^^^^^^^^^^^^
>field : any
> : ^^^
>{ a: 0 } : { a: number; }
> : ^^^^^^^^^^^^^^
>a : number
> : ^^^^^^
>0 : 0
> : ^
>a : any
> : ^^^

import * as thing6 from "./mod.mjs" assert {type: "json", field: 0..toString()}
>thing6 : typeof thing1
Expand All @@ -50,12 +50,6 @@ import * as thing6 from "./mod.mjs" assert {type: "json", field: 0..toString()}
> : ^^^
>field : any
> : ^^^
>0..toString() : string
> : ^^^^^^
>0..toString : (radix?: number) => string
> : ^ ^^^ ^^^^^
>0. : 0
> : ^
>toString : (radix?: number) => string
> : ^ ^^^ ^^^^^
>toString : any
> : ^^^

108 changes: 61 additions & 47 deletions tests/baselines/reference/importAttributes6(module=node18).errors.txt
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@@ -1,56 +1,70 @@
mod.mts(1,37): error TS2322: Type '{ field: 0; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type 'number' is not assignable to type 'string'.
mod.mts(1,51): error TS2858: Import attribute values must be string literal expressions.
mod.mts(2,51): error TS2858: Import attribute values must be string literal expressions.
mod.mts(3,37): error TS2322: Type '{ field: RegExp; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type 'RegExp' is not assignable to type 'string'.
mod.mts(3,51): error TS2858: Import attribute values must be string literal expressions.
mod.mts(4,37): error TS2322: Type '{ field: string[]; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type 'string[]' is not assignable to type 'string'.
mod.mts(4,51): error TS2858: Import attribute values must be string literal expressions.
mod.mts(5,37): error TS2322: Type '{ field: { a: number; }; }' is not assignable to type 'ImportAttributes'.
Property 'field' is incompatible with index signature.
Type '{ a: number; }' is not assignable to type 'string'.
mod.mts(5,51): error TS2858: Import attribute values must be string literal expressions.
mod.mts(6,65): error TS2858: Import attribute values must be string literal expressions.
mod.mts(3,52): error TS1005: ',' expected.
mod.mts(3,53): error TS1005: ':' expected.
mod.mts(3,54): error TS1005: ',' expected.
mod.mts(3,56): error TS1005: ':' expected.
mod.mts(3,57): error TS1005: ',' expected.
mod.mts(4,8): error TS1005: ':' expected.
mod.mts(4,10): error TS1005: ',' expected.
mod.mts(4,13): error TS1005: ':' expected.
mod.mts(4,20): error TS1005: ',' expected.
mod.mts(4,25): error TS1005: ':' expected.
mod.mts(4,37): error TS1005: ',' expected.
mod.mts(4,42): error TS1005: ':' expected.
mod.mts(4,44): error TS1005: ',' expected.
mod.mts(4,52): error TS1005: ',' expected.
mod.mts(4,55): error TS1005: ':' expected.
mod.mts(5,53): error TS1005: ',' expected.
mod.mts(5,60): error TS1128: Declaration or statement expected.
mod.mts(6,67): error TS1005: ',' expected.
mod.mts(6,76): error TS1005: ':' expected.
mod.mts(6,77): error TS1005: ',' expected.


==== mod.mts (10 errors) ====
==== mod.mts (20 errors) ====
import * as thing1 from "./mod.mjs" with { field: 0 };
~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: 0; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type 'number' is not assignable to type 'string'.
~
!!! error TS2858: Import attribute values must be string literal expressions.
import * as thing2 from "./mod.mjs" with { field: `a` };
~~~
!!! error TS2858: Import attribute values must be string literal expressions.
import * as thing3 from "./mod.mjs" with { field: /a/g };
~~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: RegExp; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type 'RegExp' is not assignable to type 'string'.
~~~~
!!! error TS2858: Import attribute values must be string literal expressions.
~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~
!!! error TS1005: ',' expected.
import * as thing4 from "./mod.mjs" with { field: ["a"] };
~~~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: string[]; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type 'string[]' is not assignable to type 'string'.
~~~~~
!!! error TS2858: Import attribute values must be string literal expressions.
~
!!! error TS1005: ':' expected.
~~
!!! error TS1005: ',' expected.
~~~~~~
!!! error TS1005: ':' expected.
~~~~
!!! error TS1005: ',' expected.
~~~~~~~~~~~
!!! error TS1005: ':' expected.
~~~~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~~~~~
!!! error TS1005: ',' expected.
~~~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
import * as thing5 from "./mod.mjs" with { field: { a: 0 } };
~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2322: Type '{ field: { a: number; }; }' is not assignable to type 'ImportAttributes'.
!!! error TS2322: Property 'field' is incompatible with index signature.
!!! error TS2322: Type '{ a: number; }' is not assignable to type 'string'.
~~~~~~~~
!!! error TS2858: Import attribute values must be string literal expressions.
~
!!! error TS1005: ',' expected.
~
!!! error TS1128: Declaration or statement expected.
import * as thing6 from "./mod.mjs" with { type: "json", field: 0..toString() };
~~~~~~~~~~~~~
!!! error TS2858: Import attribute values must be string literal expressions.
~
!!! error TS1005: ',' expected.
~
!!! error TS1005: ':' expected.
~
!!! error TS1005: ',' expected.

1 change: 1 addition & 0 deletions tests/baselines/reference/importAttributes6(module=node18).js
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Expand Up @@ -10,4 +10,5 @@ import * as thing6 from "./mod.mjs" with { type: "json", field: 0..toString() };


//// [mod.mjs]
;
export {};
5 changes: 0 additions & 5 deletions tests/baselines/reference/importAttributes6(module=node18).symbols
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Expand Up @@ -11,14 +11,9 @@ import * as thing3 from "./mod.mjs" with { field: /a/g };
>thing3 : Symbol(thing3, Decl(mod.mts, 2, 6))

import * as thing4 from "./mod.mjs" with { field: ["a"] };
>thing4 : Symbol(thing4, Decl(mod.mts, 3, 6))

import * as thing5 from "./mod.mjs" with { field: { a: 0 } };
>thing5 : Symbol(thing5, Decl(mod.mts, 4, 6))
>a : Symbol(a, Decl(mod.mts, 4, 51))

import * as thing6 from "./mod.mjs" with { type: "json", field: 0..toString() };
>thing6 : Symbol(thing6, Decl(mod.mts, 5, 6))
>0..toString : Symbol(Number.toString, Decl(lib.es5.d.ts, --, --))
>toString : Symbol(Number.toString, Decl(lib.es5.d.ts, --, --))

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