[Bug lto/80717] New: LTO wrappers segfault if run with absolute path

[theivorytower at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80717

            Bug ID: 80717
           Summary: LTO wrappers segfault if run with absolute path
           Product: gcc
           Version: 7.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: theivorytower at gmail dot com
  Target Milestone: ---

When I run any of the LTO wrappers (gcc-ar, gcc-nm, gcc-ranlib) with absolute
path (e.g. /usr/bin/gcc-ar), the program segfaults immediately. I tried to run
some debugging, and I found the culprit is in line 197-204 of gcc-ar.c.

Basically gcc-ar was trying to find ar, and "/usr/bin/" was removed from the
list of path to search for ar in line 203 of gcc-ar.c. As a result ar cannot be
found and the program segfaults.

I'm using Arch Linux and my gcc version info is as follows:

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/hao/code/gcc/src/gcc/configure --prefix=/usr
--libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,lto --enable-shared --enable-threads=posix
--enable-libmpx --with-system-zlib --with-isl --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-lto --enable-plugin --enable-install-libiberty
--with-linker-hash-style=gnu --enable-gnu-indirect-function --disable-multilib
--disable-werror --enable-checking=release
Thread model: posix
gcc version 7.1.1 20170508 (GCC)