Reverts llvm/llvm-project#145220
This breaks CI when building the documentation
```
Included from /home/runner/work/llvm-project/llvm-project/clang/docs/../include/clang/Basic/Diagnostic.td:74:
/home/runner/work/llvm-project/llvm-project/clang/docs/../include/clang/Basic/DiagnosticGroups.td:628:5: error: Diagnostic group contains both remark and non-remark diagnostics
def ModulesDriver : DiagGroup<"modules-driver">;
^
```
https://github.com/llvm/llvm-project/actions/runs/16116118496/job/45470268367
This PR is part of a series to natively support C++20 module usage from
the Clang driver (without requiring an external build system).
This introduces a new scanner that detects C++20 module usage in source
files without using the preprocessor or lexer.
For now, it is enabled only with the `-fmodules-driver` flag and serves
solely diagnostic purposes. In the future, the scanner will be enabled
for any (modules-driver compatible) compilation with two or more inputs,
and will help the driver determine whether to implicitly enable the
modules driver.
Since the scanner adds very little overhead, we are also exploring
enabling it for compilations with only a single input. This approach
could allow us to detect `import std` usage in a single-file
compilation, which would then activate the modules driver.
For performance measurements on this, see
https://github.com/naveen-seth/llvm-dev-cxx-modules-check-benchmark.
RFC:
https://discourse.llvm.org/t/rfc-modules-support-simple-c-20-modules-use-from-the-clang-driver-without-a-build-system
intent when we added remark support, but was never implemented in the general
case, because the first -R flags didn't need it. (-Rpass= had special handling
to accomodate its argument.)
-Rno-foo, -Reverything, and -Rno-everything can be used to turn off a remark,
or to turn on or off all remarks. Per discussion on cfe-commits, -Weverything
does not affect remarks, and -Reverything does not affect warnings or errors.
The only "real" -R flag we have right now is -Rmodule-build; that flag is
effectively renamed from -Wmodule-build to -Rmodule-build by this change.
-Wpass and -Wno-pass (and their friends) are also renamed to -Rpass and
-Rno-pass by this change; it's not completely clear whether we intended to have
a -Rpass (with no =pattern), but that is unchanged by this commit, other than
the flag name. The default pattern is effectively one which matches no passes.
In future, we may want to make the default pattern be .*, so that -Reverything
works for -Rpass properly.
llvm-svn: 215046
warning options to setup diagnostic state, but should not be emitting warnings as these would be
rudndant with what the frontend emits.
rdar://13001556
llvm-svn: 172497
