https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67195
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #3) > (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 > Actually it is right in the second paragraph: Furthermore, all pre-processor macros, switches, and configuration options are gathered in the file c++config.h What more is needed? > > > > > > ------ > > > > 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"?
