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). 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))) > ^ >
