https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67195
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Jeffrey Walton from comment #2) > > > > $ uname -a > > Linux localhost.localdomain 4.1.3-201.fc22.x86_64 #1 SMP Wed Jul 29 19:50:22 > > UTC 2015 x86_64 x86_64 x86_64 GNU/Linux > > > > $ g++ --version > > g++ (GCC) 5.1.1 20150618 (Red Hat 5.1.1-4) > > Copyright (C) 2015 Free Software Foundation, Inc > > (In reply to Jonathan Wakely from comment #1) > > The library macro is defined by the library, not the compiler. You didn't > > include any library headers. > > Thanks Jonathon. > > The documentation does not state that requirement. Perhaps this is a > documentation bug? I think the document assumes that since this is the library docs rather than the compiler or preprocessor doc n > > ------ > > Related, here's how I am trying to use it in a makefile: > > USING_GLIBCXX := $(shell $(CXX) $(CXXFLAGS) -E -dM - </dev/null | $(EGREP) > -i -c "__GLIBCXX__") > $(info USING_GLIBCXX: $(USING_GLIBCXX)) > > # For debug builds > ifneq ($(USING_GLIBCXX),0) > CXXFLAGS += -D_GLIBCXX_DEBUG=1 --enable-concept-checks > endif > > CXX and CXXFAGS are populated, and they hold the settings that will be used > by make to compile the source code. It kind of begs the question, how does > CXX know to use -stdlib=libstdc++ if its not specified in CXXFLAGS? > Shouldn't everything "just work" or everything "just fail"?
