public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "andrew2085 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95349] New: Using std::launder(p) produces unexpected behavior where (p) produces expected behavior
Date: Tue, 26 May 2020 20:45:24 +0000 [thread overview]
Message-ID: <bug-95349-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95349
Bug ID: 95349
Summary: Using std::launder(p) produces unexpected behavior
where (p) produces expected behavior
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: andrew2085 at gmail dot com
Target Milestone: ---
Created attachment 48609
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48609&action=edit
preprocessed ii file
All of these f1/f2/f3 functions should do the same thing, essentially the same
thing as std::start_lifetime_as. Since the return value of placement new is
used, std::launder is not necessary here, but using it anyway produces
unexpected behavior when it should do nothing at all. Every version of gcc and
every system I've tried has produced the same result.
Here's the original source for reference: https://godbolt.org/z/zdQsfV
gcc version: 10.1.0 (All other versions tested produce same behavior)
system: Arch Linux x86_64
compile command: g++ -save-temps -std=c++17 -O2 -fno-stack-protector
-fstrict-aliasing main.cpp && ./a.out
configure options: g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/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++,ada,fortran,go,lto,objc,obj-c++,d --with-isl
--with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit
--enable-cet=auto --enable-checking=release --enable-clocale=gnu
--enable-default-pie --enable-default-ssp --enable-gnu-indirect-function
--enable-gnu-unique-object --enable-install-libiberty --enable-linker-build-id
--enable-lto --enable-multilib --enable-plugin --enable-shared
--enable-threads=posix --disable-libssp --disable-libstdcxx-pch
--disable-libunwind-exceptions --disable-werror
gdc_include_dir=/usr/include/dlang/gdc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.1.0 (GCC)
next reply other threads:[~2020-05-26 20:45 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 20:45 andrew2085 at gmail dot com [this message]
2020-05-27 8:04 ` [Bug c++/95349] " rguenth at gcc dot gnu.org
2020-05-27 9:14 ` redi at gcc dot gnu.org
2020-05-27 9:40 ` rguenther at suse dot de
2020-05-27 11:05 ` redi at gcc dot gnu.org
2020-05-27 14:45 ` andrew2085 at gmail dot com
2020-05-27 15:07 ` redi at gcc dot gnu.org
2020-05-27 15:19 ` andrew2085 at gmail dot com
2020-05-27 16:01 ` andrew2085 at gmail dot com
2020-05-29 10:59 ` ed at catmur dot uk
2020-05-29 11:23 ` rguenth at gcc dot gnu.org
2020-05-29 11:32 ` rguenth at gcc dot gnu.org
2020-05-29 13:53 ` ed at catmur dot uk
2020-05-29 14:15 ` redi at gcc dot gnu.org
2020-05-29 14:24 ` rguenther at suse dot de
2020-05-29 15:05 ` andrew2085 at gmail dot com
2020-05-29 18:07 ` richard-gccbugzilla at metafoo dot co.uk
2020-05-29 21:00 ` andrew2085 at gmail dot com
2020-05-29 21:50 ` richard-gccbugzilla at metafoo dot co.uk
2020-05-29 23:13 ` andrew2085 at gmail dot com
2020-05-29 23:25 ` richard-gccbugzilla at metafoo dot co.uk
2020-06-02 12:09 ` rguenth at gcc dot gnu.org
2020-06-02 12:20 ` rguenth at gcc dot gnu.org
2020-06-02 16:00 ` andrew2085 at gmail dot com
2020-06-02 16:23 ` rguenther at suse dot de
2020-06-02 16:34 ` andrew2085 at gmail dot com
2020-06-02 16:37 ` andrew2085 at gmail dot com
2020-06-02 17:54 ` rguenther at suse dot de
2020-06-02 18:43 ` andrew2085 at gmail dot com
2020-06-02 20:53 ` andrew2085 at gmail dot com
2020-06-03 6:52 ` rguenth at gcc dot gnu.org
2020-06-04 0:27 ` andrew2085 at gmail dot com
2020-06-04 6:14 ` rguenther at suse dot de
2020-06-04 16:05 ` andrew2085 at gmail dot com
2020-06-05 6:52 ` rguenth at gcc dot gnu.org
2020-06-05 14:30 ` andrew2085 at gmail dot com
2020-06-15 9:29 ` rguenth at gcc dot gnu.org
2020-06-15 21:45 ` richard-gccbugzilla at metafoo dot co.uk
2020-06-16 3:27 ` andrew2085 at gmail dot com
2020-06-16 6:50 ` rguenther at suse dot de
2020-06-16 6:57 ` rguenther at suse dot de
2020-06-16 13:56 ` andrew2085 at gmail dot com
2022-01-11 12:43 ` rguenth at gcc dot gnu.org
2022-01-11 12:48 ` rguenth at gcc dot gnu.org
2022-11-14 4:53 ` andrew2085 at gmail dot com
2024-06-03 8:02 ` Christopher.Nerz at de dot bosch.com
2024-06-03 8:51 ` rguenth at gcc dot gnu.org
2024-06-03 9:13 ` Christopher.Nerz at de dot bosch.com
2024-06-03 9:23 ` rguenth at gcc dot gnu.org
2024-06-03 10:26 ` Christopher.Nerz at de dot bosch.com
2024-06-03 11:19 ` rguenther at suse dot de
2024-06-03 15:53 ` redi at gcc dot gnu.org
2024-06-03 16:00 ` redi at gcc dot gnu.org
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bug-95349-4@http.gcc.gnu.org/bugzilla/ \
--to=gcc-bugzilla@gcc.gnu.org \
--cc=gcc-bugs@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).