[all-commits] [llvm/llvm-project] 0b1886: [Clang] [Diagnostic] Extend DiagCompat() to C lang...

[Sirraide via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0b18869a684febeb4144cd0213cef3163b8cb37e
      https://github.com/llvm/llvm-project/commit/0b18869a684febeb4144cd0213cef3163b8cb37e
  Author: Sirraide <aeternalmail at gmail.com>
  Date:   2026-07-15 (Wed, 15 Jul 2026)

  Changed paths:
    M clang/bindings/python/tests/cindex/test_diagnostics.py
    M clang/include/clang/Basic/Diagnostic.td
    M clang/include/clang/Basic/DiagnosticIDs.h
    M clang/include/clang/Basic/DiagnosticSemaKinds.td
    M clang/lib/Basic/DiagnosticIDs.cpp
    M clang/lib/Parse/Parser.cpp
    M clang/lib/Sema/SemaBase.cpp
    M clang/lib/Sema/SemaExpr.cpp
    M clang/lib/Sema/SemaStmt.cpp
    M clang/lib/Sema/SemaType.cpp

  Log Message:
  -----------
  [Clang] [Diagnostic] Extend DiagCompat() to C language modes (#209241)

This expands the compatibility warnings infrastructure added in #132348
to support C mode as well. Implementing this was actually fairly
straight-forward because we are only ever in C _or_ C++ mode, i.e.
during a single compilation we either emit only C compatibility warnings
or only C++ compatibility warnings. This means we can simply reuse the
existing code and just check for different LangOpts depending on whether
we're in C or C++ mode.

Concretely, this means that instead of e.g.

```
def ext_c2y_alignof_incomplete_array : Extension<
  "'alignof' on an incomplete array type is a C2y extension">,
  InGroup<C2y>;
def warn_c2y_compat_alignof_incomplete_array : Warning<
  "'alignof' on an incomplete array type is incompatible with C standards "
  "before C2y">, InGroup<CPre2yCompat>, DefaultIgnore;
```

you can now simply write

```
defm alignof_incomplete_array : C2yCompat<"'alignof' on an incomplete array type is">;
```

And when emitting the warning(s), code such as

```
Diag(OpLoc, getLangOpts().C2y
                ? diag::warn_c2y_compat_alignof_incomplete_array
                : diag::ext_c2y_alignof_incomplete_array);
```

can now be replaced with

```
DiagCompat(OpLoc, diag_compat::alignof_incomplete_array);
```

I've also migrated the C compatibility warnings in
DiagnosticSemaKinds.td to use the new system to make sure that
everything is working properly.



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications