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From: "serge.ayoun at outlook dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/110321] New: Double precision comaprison does not seem to
 work well when -std=c++17 option is selected
Date: Tue, 20 Jun 2023 15:14:41 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 13.1.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: serge.ayoun at outlook dot com
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X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110321

            Bug ID: 110321
           Summary: Double precision comaprison does not seem to work well
                    when -std=3Dc++17 option is selected
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: serge.ayoun at outlook dot com
  Target Milestone: ---

The following code:

int main(int, char**)
{=20
    double a =3D 2.2;
    if ( a =3D=3D 2.2) return 1;=20
    return 0;=20
}


compiled and link with the following instruction:

g++ -O0 -m32 -std=3Dc++17

with gcc 11.1, returns 1 as expected
with gcc 13.1, returns 0.

when -std=3Dc++17 is removed, both return 0 as expected.

for exact reproduction See:

https://godbolt.org/#z:OYLghAFBqd5QCxAYwPYBMCmBRdBLAF1QCcAaPECAMzwBtMA7AQwF=
tMQByARg9KtQYEAysib0QXACx8BBAKoBnTAAUAHpwAMvAFYTStJg1DIApACYAQuYukl9ZATwDKj=
dAGFUtAK4sGe1wAyeAyYAHI%2BAEaYxHoADqgKhE4MHt6%2BcQlJAkEh4SxRMVy2mPaOAkIETMQ=
EqT5%2BRXaYDskVVQQ5YZHRegqV1bXpDX3twZ353VwAlLaoXsTI7BzBBADULEzBEMukK8gIVQBU=
B5MmGgCCJgDsFiunZysPK%2BizEfQrTLcAzAAiK2YAdGYTJ8rOdHis8FQVhB3l9vsDfgCzJMVsR=
MAQ5gwVlxgTc7uC0RjiFiNLjbucrt8ONNaJwAKy8PwcLSkVCcNzWawrBSzeaYW5mT48UgETTU6Y=
AaxAkku/zpAE4uBoAGzyz6fDRceXyy7Kun6TiSRli1mcXgKEAaEVi6ZwWAwRAoVAsWJ0aLkShoF=
1umLALhC0hYABueAWADU8JgAO4AeVijE4wpotAI0QtEAiJoiwSqAE9E7xs8xiLmYxFtE1RdxeF6=
2IIYwxaPnmbwsBEvMA3GJaBbq4HMOsjOIW4G8GjmkHML2WZhVE0vKmC%2BRBCUTbQ8BFiHmPFgT=
QRiHgWAXplQDMAFBHo3GE33%2BIIRGJ2FIZIJFCp1CPdEUDEYUJzLPoG4WpA0yoLEZQML2AC0MY=
aCsUEsJ8Zjwb06AIqYljWFwly8Kgk7EAeWDARA0yNM0zgQK4Az1KQgSjHkBQZIkEHUUxWQMB0DE=
TMUpQtMMrENCUlZ8W0nFdIUtj8Z4dQ9MMYnjIUpG8gsEg0vSxojmyHArKoAAcypQcqkgrMAyDIN=
inz/Fw0K4IQJACkKky8FWWiTJKIB0latIcEapBHpI8r/Boum6ZcZjypqyqXPpdKXKQTIslp5qWt=
aLa2g6EBIF6rr0GQFAQNlPogH6XBFMGoaYJesbxkySZ0KmxDppmI5FnmS6tSWZYVg4S61owBANk=
2Jpth2Xa0D2S5YIOwDDiy%2BDjo4k7Trws7zoufbLKuI7rpu24YIsLL7oex58GeF6RtVN5JrID7=
iM%2Bd7yEoagmroZj6IYxj/jYO3EaB4HJNBsHwYhyFQah6FfdhuH4YRU7wKRQnkX4lEMO40mDLR=
qPyYxRTxMxyQCaQePsdj3FkRBrT9OjNHkyJ1SkxJvRtITTP0/R4mqTMcwqVMBocAy8UmlpOn6YZ=
xmmeZpVWTZ%2BBEMQDlTM5NrTAgmBMFgMQkXzvlHp5/yKlwZiXBo8q6Uh/qSJ8guaWatgpS54qk=
FKdIApIwVqiqqq6RoGiCvq3mfBpiW2w7bl82YQe4SHyukPhiTOJIQA%3D

Thanks,
Serge=