[Bug bootstrap/127914] New: Bootstrap on FreeBSD dies with libiberty issue

[kargl at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127914

            Bug ID: 127914
           Summary: Bootstrap on FreeBSD dies with libiberty issue
           Product: gcc
           Version: 14.4.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kargl at gcc dot gnu.org
  Target Milestone: ---

I have tried bootstrapping master with both FreeBSD default compiler
infrastructure, which llvm 21, and with GCC 16.1.0 installed from the
FreeBSD ports collection.  Both attempts die in libiberty with the 
following type of error:

libtool: compile:  /home/kargl/gcc/obj/./gcc/xgcc -B/home/kargl/gcc/obj/./gcc/
-B/home/kargl/work/x/x86_64-unknown-freebsd16.0/bin/
-B/home/kargl/work/x/x86_64-unknown-freebsd16.0/lib/ -isystem
/home/kargl/work/x/x86_64-unknown-freebsd16.0/include -isystem
/home/kargl/work/x/x86_64-unknown-freebsd16.0/sys-include -fno-checking
-DHAVE_CONFIG_H -I.. -I/home/kargl/gcc/gcc/libstdc++-v3/../libiberty
-I/home/kargl/gcc/gcc/libstdc++-v3/../include -D_GLIBCXX_SHARED
-I/home/kargl/gcc/obj/x86_64-unknown-freebsd16.0/libstdc++-v3/include/x86_64-unknown-freebsd16.0
-I/home/kargl/gcc/obj/x86_64-unknown-freebsd16.0/libstdc++-v3/include
-I/home/kargl/gcc/gcc/libstdc++-v3/libsupc++ -O -g -DIN_GLIBCPP_V3 -Wno-error
-c cp-demangle.c  -fPIC -DPIC -o cp-demangle.o
In file included from /usr/include/stdio.h:38,
                 from cp-demangle.c:109:
/home/kargl/gcc/gcc/libstdc++-v3/../include/libiberty.h:226:14: error: expected
identifier or '(' before '_Generic'
  226 | extern void *memrchr(const void *, int, size_t);
      |              ^~~~~~~

FreeBSD manpage shows a memrchr comes from strings.h with a prototype of the
form

     QVoid *memrchr(QVoid *b, int c, size_t len);