[clang] [clang] Fix a segfault when M is a nullptr (PR #130712)

[Takuto Ikuta via cfe-commits]

================
@@ -318,6 +318,7 @@ Bug Fixes to C++ Support
 - Fixed an assertion failure affecting code that uses C++23 "deducing this". (#GH130272)
 - Clang now properly instantiates destructors for initialized members within non-delegating constructors. (#GH93251)
 - Correctly diagnoses if unresolved using declarations shadows template paramters (#GH129411)
+- Clang no longer segfaults when there is a configuration mismatch between modules and their users (http://crbug.com/400353616).
----------------
atetubou wrote:

I think it is better to refer this PR.
```suggestion
- Clang no longer segfaults when there is a configuration mismatch between modules and their users (#GH130712).
```

https://github.com/llvm/llvm-project/pull/130712