🔎 Search Terms
anonymous class decorator crash, "A class declaration that is not a default export must have a name", esDecorator visitClassDeclaration, ChildIsDecorated, typescript-go#3891, DecSoft Utils (@dec) class {}
🕗 Version & Regression Information
- This is a crash
- Also crashes TypeScript 6.0.3 (JS) with the same assert.
- Reproduced on 7.1.0-dev (
main) with emit and --target es2022 (also es5 / es2015 / es2021). --target esnext and --noEmit do not crash.
⏯ Playground Link
https://www.typescriptlang.org/play/?ts=6.0.0-dev.20260416#code/CYUwxgNghgTiAEA3W9RgFzygOwJ4G4AoAATUMigGdL4BvQgXyA
💻 Code
declare var dec: any;
@dec
class {
}🙁 Actual behavior
panic: Debug failure. False expression: A class declaration that is not a default export must have a name. [recovered, repanicked]
goroutine 107 [running]:
sync.(*WaitGroup).Go.func1.1()
sync/waitgroup.go:251 +0x48
panic({0x105ea58e0?, 0x11e74b992390?})
runtime/panic.go:860 +0x12c
github.com/microsoft/TypeScript/tsc/internal/debug.Fail(...)
github.com/microsoft/TypeScript/tsc/internal/debug/debug.go:14
github.com/microsoft/TypeScript/tsc/internal/debug.assertSlow(...)
github.com/microsoft/TypeScript/tsc/internal/debug/debug.go:60 +0x5c
github.com/microsoft/TypeScript/tsc/internal/debug.Assert(...)
github.com/microsoft/TypeScript/tsc/internal/debug/debug.go:49
github.com/microsoft/TypeScript/tsc/internal/transformers/estransforms.(*esDecoratorTransformer).visitClassDeclaration(...)
github.com/microsoft/TypeScript/tsc/internal/transformers/estransforms/esdecorator.go:1071 +0x5ec
github.com/microsoft/TypeScript/tsc/internal/transformers/estransforms.(*esDecoratorTransformer).visit(...)
github.com/microsoft/TypeScript/tsc/internal/transformers/estransforms/esdecorator.go:318 +0x35c
github.com/microsoft/TypeScript/tsc/internal/ast.(*NodeVisitor).VisitSlice(...)
github.com/microsoft/TypeScript/tsc/internal/ast/visitor.go:148 +0xa0
github.com/microsoft/TypeScript/tsc/internal/ast.(*NodeVisitor).VisitNodes(...)
github.com/microsoft/TypeScript/tsc/internal/ast/visitor.go:99 +0x3c
github.com/microsoft/TypeScript/tsc/internal/printer.(*EmitContext).VisitVariableEnvironment(...)
github.com/microsoft/TypeScript/tsc/internal/printer/emitcontext.go:796 +0x17c
... 42 lines truncated ...
github.com/microsoft/TypeScript/tsc/internal/compiler.(*emitter).emitJSFile(...)
github.com/microsoft/TypeScript/tsc/internal/compiler/emitter.go:200 +0x198
github.com/microsoft/TypeScript/tsc/internal/compiler.(*emitter).emit(...)
github.com/microsoft/TypeScript/tsc/internal/compiler/emitter.go:50 +0xec
github.com/microsoft/TypeScript/tsc/internal/compiler.(*Program).Emit.func2()
github.com/microsoft/TypeScript/tsc/internal/compiler/program.go:1851 +0x1c0
🙂 Expected behavior
The compiler should not crash 🙂
Additional information about the issue
Disclosure: This crash was found with a custom mutation fuzzer and AI assistance (Kimi K3). The input was minimized and then verified by hand against TypeScript 7.1.0-dev (main) and TypeScript 6.0.3.
This appears to be a leftover of the fix for typescript-go#3891 / typescript-go#3926 (commit 710928bdf2). That fix covers an anonymous class with a member decorator (class { @x m() {} }). It does not cover a class-level decorator (@dec class {}).
🔎 Search Terms
anonymous class decorator crash, "A class declaration that is not a default export must have a name", esDecorator visitClassDeclaration, ChildIsDecorated, typescript-go#3891, DecSoft Utils (@dec) class {}
🕗 Version & Regression Information
main) with emit and--target es2022(also es5 / es2015 / es2021).--target esnextand--noEmitdo not crash.⏯ Playground Link
https://www.typescriptlang.org/play/?ts=6.0.0-dev.20260416#code/CYUwxgNghgTiAEA3W9RgFzygOwJ4G4AoAATUMigGdL4BvQgXyA
💻 Code
🙁 Actual behavior
🙂 Expected behavior
The compiler should not crash 🙂
Additional information about the issue
Disclosure: This crash was found with a custom mutation fuzzer and AI assistance (Kimi K3). The input was minimized and then verified by hand against TypeScript 7.1.0-dev (
main) and TypeScript 6.0.3.This appears to be a leftover of the fix for typescript-go#3891 / typescript-go#3926 (commit
710928bdf2). That fix covers an anonymous class with a member decorator (class { @x m() {} }). It does not cover a class-level decorator (@dec class {}).