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Fix crash in isolatedDeclarations on this.x = … assignments #64471

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0cae8a5
Add tests for isolatedDeclarations crash on non-identifier-rooted pro…
Andarist Sep 26, 2026
1de0adc
Fix crash in isolatedDeclarations on this/super/call-rooted property …
Andarist Sep 26, 2026
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8 changes: 7 additions & 1 deletion tsc/internal/transformers/declarations/tracker.go
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Expand Up @@ -61,7 +61,13 @@ func (s *SymbolTrackerImpl) isBoundExpando(node *ast.Node) bool {
if !(ast.IsExpandoPropertyDeclaration(node) && ast.IsPropertyAccessExpression(node.AsBinaryExpression().Left)) {
return false
}
ref := s.resolver.GetReferencedValueDeclarationUnsafe(ast.GetLeftmostExpression(node.AsBinaryExpression().Left, true))

@Andarist Mateusz Burzyński (Andarist) Sep 26, 2026

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With isolatedDeclarations on, if a type can't be inferred, the Go declaration emitter reports an error. Before reporting, it checks if the node is inside an expando assignment like f.x = …, so it doesn't report the same problem twice. This check (isBoundExpando) treated every a.b = … assignment as rooted at a name and passed that root to name lookup.

But with this.x = foo() the root is the this keyword, not a name, so the lookup's Node.Text() would just panic.

// Match transformExpandoAssignment: only an assignment rooted at an identifier (`f.x = ...`) can bind an expando
// property; `this.x = ...`, `super.x = ...`, `f().x = ...` and the like have no referenced declaration.
ns := ast.GetLeftmostAccessExpression(node.AsBinaryExpression().Left)
if !ast.IsIdentifier(ns) {
return false
}
ref := s.resolver.GetReferencedValueDeclarationUnsafe(ns)
if ref == nil {
return false
}
Expand Down
15 changes: 15 additions & 0 deletions ...lines/reference/compiler/isolatedDeclarationsJsThisPropertyAssignmentInference.errors.txt
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error TS5053: Option 'allowJs' cannot be specified with option 'isolatedDeclarations'.
a.js(4,9): error TS9013: Expression type can't be inferred with --isolatedDeclarations.


!!! error TS5053: Option 'allowJs' cannot be specified with option 'isolatedDeclarations'.
==== a.js (1 errors) ====
function foo() { return 1; }
export class C {
constructor() {
this.x = foo();
~~~~~~~~~~~~~~
!!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
}
}

18 changes: 18 additions & 0 deletions ...aselines/reference/compiler/isolatedDeclarationsJsThisPropertyAssignmentInference.symbols
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//// [tests/cases/compiler/isolatedDeclarationsJsThisPropertyAssignmentInference.ts] ////

=== a.js ===
function foo() { return 1; }
>foo : Symbol(foo, Decl(a.js, 0, 0))

export class C {
>C : Symbol(C, Decl(a.js, 0, 28))

constructor() {
this.x = foo();
>this.x : Symbol(C.x, Decl(a.js, 2, 19))
>this : Symbol(C, Decl(a.js, 0, 28))
>x : Symbol(C.x, Decl(a.js, 2, 19))
>foo : Symbol(foo, Decl(a.js, 0, 0))
}
}

21 changes: 21 additions & 0 deletions .../baselines/reference/compiler/isolatedDeclarationsJsThisPropertyAssignmentInference.types
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//// [tests/cases/compiler/isolatedDeclarationsJsThisPropertyAssignmentInference.ts] ////

=== a.js ===
function foo() { return 1; }
>foo : () => number
>1 : 1

export class C {
>C : C

constructor() {
this.x = foo();
>this.x = foo() : number
>this.x : any
>this : this
>x : any
>foo() : number
>foo : () => number
}
}

38 changes: 38 additions & 0 deletions ...piler/isolatedDeclarationsNonIdentifierAssignmentInference(isolateddeclarations=false).js
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//// [tests/cases/compiler/isolatedDeclarationsNonIdentifierAssignmentInference.ts] ////

//// [isolatedDeclarationsNonIdentifierAssignmentInference.ts]
declare function foo(): number;
declare function bar(): { x: number };
class Base { get y(): number { return 0; } set y(v: number) {} }
export class C extends Base {
z = 0;
a = { p: (this.z = foo()) };
b = { p: (super.y = foo()) };
c = { p: (bar().x = foo()) };
}
export const d = { p: (bar().x = foo()) };




//// [isolatedDeclarationsNonIdentifierAssignmentInference.d.ts]
declare class Base {
get y(): number;
set y(v: number);
}
export declare class C extends Base {
z: number;
a: {
p: number;
};
b: {
p: number;
};
c: {
p: number;
};
}
export declare const d: {
p: number;
};
export {};
55 changes: 55 additions & 0 deletions .../isolatedDeclarationsNonIdentifierAssignmentInference(isolateddeclarations=false).symbols
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//// [tests/cases/compiler/isolatedDeclarationsNonIdentifierAssignmentInference.ts] ////

=== isolatedDeclarationsNonIdentifierAssignmentInference.ts ===
declare function foo(): number;
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

declare function bar(): { x: number };
>bar : Symbol(bar, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 31))
>x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))

class Base { get y(): number { return 0; } set y(v: number) {} }
>Base : Symbol(Base, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 38))
>y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>v : Symbol(v, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 49))

export class C extends Base {
>C : Symbol(C, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 64))
>Base : Symbol(Base, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 38))

z = 0;
>z : Symbol(C.z, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 3, 29))

a = { p: (this.z = foo()) };
>a : Symbol(C.a, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 4, 10))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 5, 9))
>this.z : Symbol(C.z, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 3, 29))
>this : Symbol(C, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 64))
>z : Symbol(C.z, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 3, 29))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

b = { p: (super.y = foo()) };
>b : Symbol(C.b, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 5, 32))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 6, 9))
>super.y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>super : Symbol(Base, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 38))
>y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

c = { p: (bar().x = foo()) };
>c : Symbol(C.c, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 6, 33))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 7, 9))
>bar().x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>bar : Symbol(bar, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 31))
>x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))
}
export const d = { p: (bar().x = foo()) };
>d : Symbol(d, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 9, 12))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 9, 18))
>bar().x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>bar : Symbol(bar, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 31))
>x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

75 changes: 75 additions & 0 deletions ...er/isolatedDeclarationsNonIdentifierAssignmentInference(isolateddeclarations=false).types
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//// [tests/cases/compiler/isolatedDeclarationsNonIdentifierAssignmentInference.ts] ////

=== isolatedDeclarationsNonIdentifierAssignmentInference.ts ===
declare function foo(): number;
>foo : () => number

declare function bar(): { x: number };
>bar : () => { x: number; }
>x : number

class Base { get y(): number { return 0; } set y(v: number) {} }
>Base : Base
>y : number
>0 : 0
>y : number
>v : number

export class C extends Base {
>C : C
>Base : Base

z = 0;
>z : number
>0 : 0

a = { p: (this.z = foo()) };
>a : { p: number; }
>{ p: (this.z = foo()) } : { p: number; }
>p : number
>(this.z = foo()) : number
>this.z = foo() : number
>this.z : number
>this : this
>z : number
>foo() : number
>foo : () => number

b = { p: (super.y = foo()) };
>b : { p: number; }
>{ p: (super.y = foo()) } : { p: number; }
>p : number
>(super.y = foo()) : number
>super.y = foo() : number
>super.y : number
>super : Base
>y : number
>foo() : number
>foo : () => number

c = { p: (bar().x = foo()) };
>c : { p: number; }
>{ p: (bar().x = foo()) } : { p: number; }
>p : number
>(bar().x = foo()) : number
>bar().x = foo() : number
>bar().x : number
>bar() : { x: number; }
>bar : () => { x: number; }
>x : number
>foo() : number
>foo : () => number
}
export const d = { p: (bar().x = foo()) };
>d : { p: number; }
>{ p: (bar().x = foo()) } : { p: number; }
>p : number
>(bar().x = foo()) : number
>bar().x = foo() : number
>bar().x : number
>bar() : { x: number; }
>bar : () => { x: number; }
>x : number
>foo() : number
>foo : () => number

34 changes: 34 additions & 0 deletions ...solatedDeclarationsNonIdentifierAssignmentInference(isolateddeclarations=true).errors.txt
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isolatedDeclarationsNonIdentifierAssignmentInference.ts(6,15): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
isolatedDeclarationsNonIdentifierAssignmentInference.ts(7,15): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
isolatedDeclarationsNonIdentifierAssignmentInference.ts(8,15): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
isolatedDeclarationsNonIdentifierAssignmentInference.ts(10,24): error TS9013: Expression type can't be inferred with --isolatedDeclarations.


==== isolatedDeclarationsNonIdentifierAssignmentInference.ts (4 errors) ====
declare function foo(): number;
declare function bar(): { x: number };
class Base { get y(): number { return 0; } set y(v: number) {} }
export class C extends Base {
z = 0;
a = { p: (this.z = foo()) };
~~~~~~~~~~~~~~
!!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
!!! related TS9029 isolatedDeclarationsNonIdentifierAssignmentInference.ts:6:5: Add a type annotation to the property a.
!!! related TS9035 isolatedDeclarationsNonIdentifierAssignmentInference.ts:6:15: Add satisfies and a type assertion to this expression (satisfies T as T) to make the type explicit.
b = { p: (super.y = foo()) };
~~~~~~~~~~~~~~~
!!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
!!! related TS9029 isolatedDeclarationsNonIdentifierAssignmentInference.ts:7:5: Add a type annotation to the property b.
!!! related TS9035 isolatedDeclarationsNonIdentifierAssignmentInference.ts:7:15: Add satisfies and a type assertion to this expression (satisfies T as T) to make the type explicit.
c = { p: (bar().x = foo()) };
~~~~~~~~~~~~~~~
!!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
!!! related TS9029 isolatedDeclarationsNonIdentifierAssignmentInference.ts:8:5: Add a type annotation to the property c.
!!! related TS9035 isolatedDeclarationsNonIdentifierAssignmentInference.ts:8:15: Add satisfies and a type assertion to this expression (satisfies T as T) to make the type explicit.
}
export const d = { p: (bar().x = foo()) };
~~~~~~~~~~~~~~~
!!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
!!! related TS9027 isolatedDeclarationsNonIdentifierAssignmentInference.ts:10:14: Add a type annotation to the variable d.
!!! related TS9035 isolatedDeclarationsNonIdentifierAssignmentInference.ts:10:24: Add satisfies and a type assertion to this expression (satisfies T as T) to make the type explicit.

55 changes: 55 additions & 0 deletions ...r/isolatedDeclarationsNonIdentifierAssignmentInference(isolateddeclarations=true).symbols
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//// [tests/cases/compiler/isolatedDeclarationsNonIdentifierAssignmentInference.ts] ////

=== isolatedDeclarationsNonIdentifierAssignmentInference.ts ===
declare function foo(): number;
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

declare function bar(): { x: number };
>bar : Symbol(bar, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 31))
>x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))

class Base { get y(): number { return 0; } set y(v: number) {} }
>Base : Symbol(Base, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 38))
>y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>v : Symbol(v, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 49))

export class C extends Base {
>C : Symbol(C, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 64))
>Base : Symbol(Base, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 38))

z = 0;
>z : Symbol(C.z, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 3, 29))

a = { p: (this.z = foo()) };
>a : Symbol(C.a, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 4, 10))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 5, 9))
>this.z : Symbol(C.z, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 3, 29))
>this : Symbol(C, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 64))
>z : Symbol(C.z, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 3, 29))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

b = { p: (super.y = foo()) };
>b : Symbol(C.b, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 5, 32))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 6, 9))
>super.y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>super : Symbol(Base, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 38))
>y : Symbol(Base.y, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 12), Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 2, 42))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

c = { p: (bar().x = foo()) };
>c : Symbol(C.c, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 6, 33))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 7, 9))
>bar().x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>bar : Symbol(bar, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 31))
>x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))
}
export const d = { p: (bar().x = foo()) };
>d : Symbol(d, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 9, 12))
>p : Symbol(p, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 9, 18))
>bar().x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>bar : Symbol(bar, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 31))
>x : Symbol(x, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 1, 25))
>foo : Symbol(foo, Decl(isolatedDeclarationsNonIdentifierAssignmentInference.ts, 0, 0))

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