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From: "gcc at pauldreik dot se" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/111162] New: signed integer overflow triggered by
 std::chrono::parse
Date: Sat, 26 Aug 2023 12:42:13 +0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 14.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: gcc at pauldreik dot se
X-Bugzilla-Status: UNCONFIRMED
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111162

            Bug ID: 111162
           Summary: signed integer overflow triggered by
                    std::chrono::parse
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at pauldreik dot se
  Target Milestone: ---

The following program:

#include <chrono>
#include <format>
#include <sstream>
int main() {
    std::istringstream is("21474837");
    std::chrono::minutes x;
    is >> std::chrono::parse("%8C", x);
}

invokes undefined behaviour. If compiled with the current gcc trunk, one ge=
ts
this when executed:
/opt/compiler-explorer/gcc-trunk-20230824/include/c++/14.0.0/bits/chrono_io=
.h:3174:20:
runtime error: signed integer overflow: 21474837 * 100 cannot be represente=
d in
type 'int'

link to reproducer (uses gcc trunk, may go stale quick):
https://godbolt.org/z/h617GT4EY=