[Cheng (chengchuu)]

Summary

Fixes #64666

Report inaccessible heritage types instead of crashing during declaration emit. Recognize heritage type references as diagnostic contexts, preserve the enclosing context for class expressions, and use TS4082 for unnamed default-exported implementing classes to avoid malformed TS4019 messages.

Added regression coverage for interface extends, class implements, an inaccessible type argument, named and anonymous class expressions, and an unnamed default-exported class declaration.

Reproduction

The standalone reproduction prints panic: Diagnostic emitted without context and exits 2. The compiler should report diagnostics for the invalid input without crashing.

Validation

I manually ran the following checks from the repository root on macOS ARM64. All passed:

go -C ./tsc test \
  -run='TestLocal/(declarationEmitInaccessibleHeritageType|declarationEmitExpressionInExtends|declarationEmitForDefaultExportClassExtendingExpression|declarationEmitDefaultExport)' \
  ./internal/testrunner -count=1 -v
npx hereby test
npx hereby lint
npx hereby check:format

AI assistance: Copilot helped generate the regression tests. I reviewed the changes and will handle any review feedback or revisions myself.

[Copilot]

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[Copilot]

🔵 Needs a closer look

Class-expression heritage bases are not fully handled and may still produce incorrect diagnostics.

No open issues 🎉

_{Review effort: Lite}

[Copilot]

🟡 Changes recommended

The new context selects TS4019 for an unnamed default-exported class, producing a malformed diagnostic instead of using the existing default-export diagnostic.

1 open issue

• Use the default-export diagnostic for unnamed implementing classes · New

_{Review effort: Max}

[Copilot]

🔵 Needs a closer look

Human assessment is needed to weigh an unpublished, low-severity concern about duplicated node checks drifting apart and disrupting declaration diagnostics.

No open issues 🎉

1 resolved since last review

• Use the default-export diagnostic for unnamed implementing classes

_{Review effort: Max}