[all-commits] [llvm/llvm-project] c60921: [clang] Fix isInStdNamespace for Decl flagged exte...

[Fred Tingaud via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c609211d912dfa9849c5ca873d40d10e32e0a975
      https://github.com/llvm/llvm-project/commit/c609211d912dfa9849c5ca873d40d10e32e0a975
  Author: Fred Tingaud <95592999+frederic-tingaud-sonarsource at users.noreply.github.com>
  Date:   2024-02-15 (Thu, 15 Feb 2024)

  Changed paths:
    M clang/docs/ReleaseNotes.rst
    M clang/lib/AST/DeclBase.cpp
    M clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp

  Log Message:
  -----------
  [clang] Fix isInStdNamespace for Decl flagged extern c++ (#81776)

The MSVC STL implementation declares multiple classes using:

```cpp
namespace std {
  extern "C++" class locale {
    ...
  };
}
```

`isInStdNamespace` uses the first DeclContext to check whether a Decl is
inside the `std` namespace. Here, the first DeclContext of the `locale`
Decl is a LinkageSpecDecl so the method will return false.
We need to skip this LinkageSpecDecl to find the first DeclContext of
type Namespace and actually check whether we're in the `std` namespace.