On 21/04/16 12:36, Richard Biener wrote: > On Thu, Apr 21, 2016 at 1:11 PM, Szabolcs Nagy <szabolcs.n...@arm.com> wrote: >> building gcc6 using musl based gcc6 fails with symbol poisoning error >> (details at the end of the mail). >> >> the root cause is c++: c++ headers include random libc headers with >> _GNU_SOURCE ftm so all sorts of unexpected symbols are defined/declared. >> >> since it's unlikely the c++ standard gets fixed (to properly specify >> the namespace rules) it is not acceptable to include std headers after >> system.h, where the poisoning happens, because trivial libc header >> change will break the build. >> >> c++ header use in gcc seems inconsistent, e.g. there are cases where >> - <string> is included before system.h (go-system.h) >> - <string> is included after system.h (indirectly through <map>) >> - <string> is included in system.h because INCLUDE_STRING is defined. >> - <new> is included in system.h and in source files using it.. sometimes >> >> i think it should be consistently before system.h (i'm not sure what's >> going on with the INCLUDE_STRING macro), fortunately not many files are >> affected in gcc/: > > system headers should be included from _within_ system.h. To avoid including > them everywhere we use sth like > > /* Include <string> before "safe-ctype.h" to avoid GCC poisoning > the ctype macros through safe-ctype.h */ > > #ifdef __cplusplus > #ifdef INCLUDE_STRING > # include <string> > #endif > #endif > > so sources do > > #define INCLUDE_STRING > #include "config.h" > #include "system.h" > > So the <string> cases can be simplified with INCLUDE_STRING and the > <new> case should be added similarly (unless we decide <new> is cheap > enough to be always included). >
<new> is always included already. there is also <map>, <set>, <list> usage and go-system.h is special. (and gmp.h includes <iosfwd> when built with c++) so i can prepare a patch with INCLUDE_{MAP,SET,LIST} and remove the explicit libc/libstdc++ includes. > Richard. > >> auto-profile.c >> diagnostic.c >> graphite-isl-ast-to-gimple.c >> ipa-icf.c >> ipa-icf-gimple.c >> pretty-print.c >> toplev.c >> >> i can prepare a patch moving the c++ includes up and i'm open to >> other suggestions. (including libc headers is also problematic because >> of _GNU_SOURCE, but still safer than what is happening in c++ land >> where #include <map> makes all locale.h, pthread.h, time.h, sched.h, >> etc symbols visible). >> >> >> x86_64-linux-musl-g++ -fno-PIE -c -g -O2 -DIN_GCC -fno-exceptions >> -fno-rtti -fasynchronous-unwind-tables >> -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual >> -Wmissing-format-attribute -Woverloaded-virtual -pedantic >> -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings >> -DHAVE_CONFIG_H -I. -I. -I/src/gcc/gcc >> -I/src/gcc/gcc/. -I/src/gcc/gcc/../include -I/src/gcc/gcc/../libcpp/include >> -I/build/host-tools/include >> -I/build/host-tools/include -I/build/host-tools/include >> -I/src/gcc/gcc/../libdecnumber >> -I/src/gcc/gcc/../libdecnumber/dpd -I../libdecnumber >> -I/src/gcc/gcc/../libbacktrace -o auto-profile.o -MT >> auto-profile.o -MMD -MP -MF ./.deps/auto-profile.TPo >> /src/gcc/gcc/auto-profile.c >> In file included from /tool/x86_64-linux-musl/include/pthread.h:30:0, >> from >> /tool/x86_64-linux-musl/include/c++/6.0.1/x86_64-linux-musl/bits/gthr-default.h:35, >> from >> /tool/x86_64-linux-musl/include/c++/6.0.1/x86_64-linux-musl/bits/gthr.h:148, >> from >> /tool/x86_64-linux-musl/include/c++/6.0.1/ext/atomicity.h:35, >> from >> /tool/x86_64-linux-musl/include/c++/6.0.1/bits/basic_string.h:39, >> from /tool/x86_64-linux-musl/include/c++/6.0.1/string:52, >> from /tool/x86_64-linux-musl/include/c++/6.0.1/stdexcept:39, >> from /tool/x86_64-linux-musl/include/c++/6.0.1/array:39, >> from /tool/x86_64-linux-musl/include/c++/6.0.1/tuple:39, >> from >> /tool/x86_64-linux-musl/include/c++/6.0.1/bits/stl_map.h:63, >> from /tool/x86_64-linux-musl/include/c++/6.0.1/map:61, >> from /src/gcc/gcc/auto-profile.c:36: >> /tool/x86_64-linux-musl/include/sched.h:74:7: error: attempt to use poisoned >> "calloc" >> void *calloc(size_t, size_t); >> ^ >> /tool/x86_64-linux-musl/include/sched.h:114:36: error: attempt to use >> poisoned "calloc" >> #define CPU_ALLOC(n) ((cpu_set_t *)calloc(1,CPU_ALLOC_SIZE(n))) >> ^ >> >