aaron.ballman added inline comments.
================ Comment at: test/clang-tidy/google-global-names.cpp:13-14 +// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'i' declared in the global namespace +extern int ii = 0; +// CHECK-MESSAGES: :[[@LINE-1]]:12: warning: 'ii' declared in the global namespace + ---------------- bkramer wrote: > aaron.ballman wrote: > > aaron.ballman wrote: > > > bkramer wrote: > > > > aaron.ballman wrote: > > > > > This strikes me as being intentional enough to warrant not diagnosing > > > > > because of the `extern` keyword. > > > > The only case I see where this pattern is valuable is interfacing with > > > > C code. Not sure yet if we want to allow that or enforce extern "C" > > > > instead. Ideas? > > > > > > > > an extern global in the global namespace still feels like something we > > > > should warn on :| > > > Yet externs in the global namespace do happen for valid reasons (such as > > > not breaking ABIs by putting the extern definition into a namespace or > > > changing the language linkage) -- I'm trying to think of ways we can > > > allow the user to silence this diagnostic in those cases. I feel like in > > > cases where the user writes "extern", they're explicitly specifying their > > > intent and that doesn't seem like a case to warn them about, in some > > > regards. It would give us two ways to silence the diagnostic (well, > > > three, but two are morally close enough): > > > > > > 1) Put it into a namespace > > > 2) Slap `extern` on it if it is global for C++ compatibility (such as > > > ABIs) > > > 3) Slap `extern "C"` on it if it global for C compatibility > > > > > > I suppose we could require `extern "C++"` instead of `extern`, but I > > > don't think that's a particularly common use of the language linkage > > > specifier? > > I still think that a user explicitly writing 'extern' is expecting external > > linkage and all that goes along with it. > I disagree. If this is a special variable to be accessed via dlopen it should > be extern "C". If not it should be in a namespace. I'm thinking more that it's not a special variable to be accessed via dlopen, but instead is a special implementation detail that doesn't need to be exposed via a header file. For instance, see ClangTidyMain.cpp. Such uses have no way to silence this check, which may be fine since it's in the Google module. I merely wanted to point it out because it does happen for valid reasons, and having a way to silence a diagnostic aside from NOLINT is nice. https://reviews.llvm.org/D23130 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
