llvm

9809384a - [clang][modules] -Wmodule-import-in-extern-c should not be an error by default (#184530)

[clang][modules] -Wmodule-import-in-extern-c should not be an error by default (#184530) Importing a module inside of an `extern "C" {...}` section doesn't have any effect, i.e. the imported module is not treated as `extern "C"`, it's built independent of the includer state. The warning is akin to `-Wconfig-macros`, it's trying to say that the behavior will be different (and unexpected) when compiling with modules. That doesn't need to be an error, a warning is enough. As an error, it makes it difficult to support and test modules in C++ mode while dependencies still have includes in `extern "C" {...}`. rdar://171677028