Allow Program#getSemanticDiagnostics to ignore @ts-ignore

[ajafff]

Search Terms

ts-ignore

Suggestion

Add a parameter to program.getSemanticDiagnostics to turn off filtering by // @ts-ignore comments.

Use Cases

#25166 proposes an option to report unused // @ts-ignore comments. Since this would require yet another compilerOption, I think this should better be done by external tooling like a linter.

Currently there is no way for external tools to know if there would actually be a semantic diagnostic without the comment. With the proposed API one could check that there is at least one diagnostic per ignore comment.

[0rvar]

Is this really the way to go? This would mean that the linter would have to run TSC twice on each file just to lint it. It seems like this would be much more performant if it was implemented as a warning in TSC itself.
However, this would require parsing @ts-ignore comments and tracking whether they were applied...

[rattrayalex-stripe]

Raising a compiler error on unused tsc-ignore comment would be ideal.

Currently, when types get fixed, the comments get left around (there's no way to systematically find & remove them), which may silence other, unrelated errors that happened to occur on the same line as a previously-errroring type.

This is the behavior of // $FlowFixMe and has proved invaluable in library upgrades and other situations.

Of course, changing this to an error would cause many errors in some codebases, but I think that's typical of many minor releases of TS (plus, it's an exceedingly easy thing to fix).

[justjake]

We'd love to have this feature at Notion. We want to build linters that enforce correct use of // ts-ignore-error for specific error cases, or with extra metadata in the comment that narrow down what error is ignored.