From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id A323F3858018; Wed, 20 Jan 2021 07:48:53 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org A323F3858018
From: "boris at kolpackov dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/98761] New: [modules] use of a module causes SIGSEGV at
 runtime
Date: Wed, 20 Jan 2021 07:48:53 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: boris at kolpackov dot net
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-98761-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Wed, 20 Jan 2021 07:48:53 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98761

            Bug ID: 98761
           Summary: [modules] use of a module causes SIGSEGV at runtime
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: boris at kolpackov dot net
  Target Milestone: ---

The attached executable catches SIGSEGV when built with a module:

$ g++ -std=3Dc++2a -fmodules-ts -x c++ -c format.mxx
$ g++ -std=3Dc++2a -fmodules-ts -x c++ -c driver.cxx
$ g++ -std=3Dc++2a -fmodules-ts -o test driver.o format.o
$ ./test
Segmentation fault (core dumped)
$ gdb test core
(gdb) bt
#0  __memcpy_avx_unaligned () at
../sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S:148
#1  0x0000000000402cc7 in std::char_traits<char>::copy(char*, char const*,
unsigned long) ()
#2  0x000000000040405c in std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*,
unsigned long) ()
#3  0x0000000000403f72 in std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char
const*, char const*) ()
#4  0x00000000004039b0 in void std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_M_construct<char const*>(c=
har
const*, char const*, std::forward_iterator_tag) ()
#5  0x0000000000403635 in void std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char
const*>(char const*, char const*, std::__false_type)
    ()
#6  0x0000000000403337 in void std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_M_construct<char const*>(c=
har
const*, char const*) ()
#7  0x0000000000403072 in std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::basic_string(char const*,
unsigned long, std::allocator<char> const&) ()
#8  0x00000000004033fc in std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char>
>::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::__sv_wrapper, std::allocator<char> const&) ()
#9  0x00000000004030ef in std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char>
>::basic_string<std::basic_string_view<char, std::char_traits<char> >,
void>(std::basic_string_view<char, std::char_traits<char> > const&,
std::allocator<char> const&) ()
#10 0x000000000040266b in
hello::format_hello[abi:cxx11](std::basic_string_view<char,
std::char_traits<char> > const&) ()
#11 0x00000000004020be in main ()

The same code works fine if I get rid of the module. Re-ordering the object
files during linking also helps:


$ g++ -std=3Dc++2a -fmodules-ts -o test format.o driver.o=