[Bug c++/70702] New: Build failure of ARM cross compiler under Cygwin - libc_name_p

["olivier at gautherot dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70702

            Bug ID: 70702
           Summary: Build failure of ARM cross compiler under Cygwin -
                    libc_name_p
           Product: gcc
           Version: 5.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olivier at gautherot dot net
  Target Milestone: ---

Created attachment 38296
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38296&action=edit
Build script for reference

I tried to build an ARM cross compiler under Cygwin64 and got an error (symbol
not found) on libc_name_p. After some investigation, I tracked the root cause
down to the files gcc/cp/cfns.{h,gperf}. I suggest the following fix:

Replace

  "const char * libc_name_p (const char *, unsigned int);"

with

  "static const char * libc_name_p (const char *, unsigned int);"

By adding the "static" keyword, we ensure that the function is properly
inlined. There are 3 occurrences in cfns.h and cfns.gperf.

I attached my build scripts for reference.

Note: The same build scripts worked fine under Linux (Ubuntu, Centos) and
FreeBSD, with various versions of GCC and Clang/FreeBSD. The reason why GCC on
Cygwin misbehaved is still unclear.