Enze Li wrote: > > PR build/28413 notes that the gdb master fails to build on macOS.
The build fails due to the combination of '-Werror' and a useful warning emitted by Gnulib. But Gnulib does not support '-Werror'. To fix the issue, you need to filter out the '-Werror' option. Or not add it in the first place. > > Based on De Morgan's law, the expression > > !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__) > > is equal to (!defined __GNUC__ || defined __clang__ || !__OPTIMIZE). > > The expression above looks weird, maybe there are some problems with > > this way of judging. When any one of the conditions is established, the > > subsequent judgment will be ignored. > > > > This patch works around the issue by rewriting the expression of > > judgment after referring to the nearby notes. This text does not explain what the patch does. > > --- a/gnulib/import/c++defs.h > > +++ b/gnulib/import/c++defs.h > > @@ -286,7 +286,7 @@ > > _GL_CXXALIASWARN_2 (func, namespace) > > /* To work around GCC bug > > <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>, > > we enable the warning only when not optimizing. */ > > -# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__) > > +# if defined __GNUC__ && !defined __clang__ && !__OPTIMIZE__ > > # define _GL_CXXALIASWARN_2(func,namespace) \ > > _GL_WARN_ON_USE (func, \ > > "The symbol ::" #func " refers to the system > > function. " \ The previous code enables a useful warning for clang, and does not enable it for GCC because that would trigger a GCC bug. Your patch swaps the cases of clang and GCC. Thus it removes a useful warning for clang builds, and triggers a known GCC bug in the GCC builds. > > @@ -314,7 +314,7 @@ > > _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, > > namespace) > > /* To work around GCC bug > > <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>, > > we enable the warning only when not optimizing. */ > > -# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__) > > +# if defined __GNUC__ && !defined __clang__ && !__OPTIMIZE__ > > # define > > _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \ > > _GL_WARN_ON_USE_CXX (func, rettype, rettype, > > parameters_and_attributes, \ > > "The symbol ::" #func " refers to the system > > function. " \ Likewise. So, the patch is bad on all accounts. Bruno
