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From: "bazhenov.dn at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/96749] New: [coroutines] unexpected 'warning: statement has no effect [-Wunused-value]'
Date: Sun, 23 Aug 2020 05:57:37 +0000 [thread overview]
Message-ID: <bug-96749-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96749
Bug ID: 96749
Summary: [coroutines] unexpected 'warning: statement has no
effect [-Wunused-value]'
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: bazhenov.dn at gmail dot com
Target Milestone: ---
C++ compiler throws unexpected 'statement with no effect' warning at the ending
brace of a coroutine function when it utilizes co_await expression returning
non-void value which is used as an rvalue within operators '+=', '-=', '*=',
etc.
The warning doesn't appear if the co_await expression is used as an rvalue
within simple assignment ('=') to a temporary variable and then the latter used
within '+=' or other operation.
The attached test code is composed to reveal the issue but is not meant to do
any job. The "#if" alternative in the code can be used to show how warning
disappears.
In a case of meaningful code which causes the warning the code works as
expected.
- g++ version:
g++ (GCC) 11.0.0 20200822 (experimental)
- configure pameters:
configure --disable-multilib
- system:
Linux beauty 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020
x86_64 x86_64 x86_64 GNU/Linux
- compiler command:
g++ -std=c++20 -O0 -g -Wall -fcoroutines -o test test.cpp
next reply other threads:[~2020-08-23 5:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-23 5:57 bazhenov.dn at gmail dot com [this message]
2020-08-23 5:59 ` [Bug c++/96749] " bazhenov.dn at gmail dot com
2020-12-04 14:13 ` max at duempel dot org
2021-03-04 20:38 ` iains at gcc dot gnu.org
2021-03-12 15:36 ` iains at gcc dot gnu.org
2021-03-15 15:49 ` cvs-commit at gcc dot gnu.org
2021-03-22 22:04 ` cvs-commit at gcc dot gnu.org
2021-03-24 12:38 ` iains at gcc dot gnu.org
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