CodeFixes triggered by cross file diagnostics don't work #49856
Description
When updating our Analyzer Test packages: #49843
We found out that "non-local" diagnostics don't let code fixes work. Manual testing also shows that non-local diagnostics don't show a squiggle in VS or a Warning in the VS Error List window. But does show the warning in the build output.
Currently our tests workaround the problem by setting SkipLocalDiagnosticCheck. But we should figure out what to do with our Code Fixers, and whether emitted diagnostics should avoid emitting diagnostics for other files or if VS has a bug there.
Refer to dotnet/roslyn#57621 (comment) for some context