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From: "pavel.kryukov at phystech dot edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/103853] New: std::forward_list::merge should check if
 __list != this
Date: Tue, 28 Dec 2021 20:43:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103853

            Bug ID: 103853
           Summary: std::forward_list::merge should check if __list !=3D
                    this
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pavel.kryukov at phystech dot edu
  Target Milestone: ---

Created attachment 52080
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D52080&action=3Dedit
check if __list=3D=3Dthis in std::forward_list::merge

C++ standard does not require 'do nothing' if std::forward_list::merge argu=
ment
equals to 'this', however it does not say 'undefined behavior' or 'infinite
loop' too.

I've attached my patch to fix and test it, but since I'm not an experienced=
 GCC
contributor, I don't know how to run the tests. Following instructions on
CONTRIBUTING page builds whole GCC ending with some problems with my machin=
e. I
would be grateful if you tell how I can test only libstdc++.=