Hello, The attached patch helps fix a build failure of libstdc++ on some variants of VxWorks where the system headers expose an "isblank" macro. I understand this kind of thing normally is handled through fixincludes, however fixincludes on VxWorks is very tricky and we already have libstdc++-v3/include/c_global/cctype:#undef isblank libstdc++-v3/include/tr1/cctype:#undef isblank so the suggestion here is to simply do the same in a couple more places. I checked that it gets us through the observed build failure for VxWorks, then bootstrapped and regtested on native 64bit linux. Ok to commit? Thanks in advance, With Kind Regards, Olivier 2021-12-07 Olivier Hainque libstdc++-v3/ * include/bits/locale_facets.h: #undef isblank before providing a definition. * libstdc++-v3/include/bits/localefwd.h: Likewise.