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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/96182] GCC accepts constexpr function with no
 return-statement
Date: Mon, 13 Jul 2020 12:28:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96182

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
           Keywords|accepts-invalid             |diagnostic
   Last reconfirmed|                            |2020-07-13
           Severity|normal                      |enhancement

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
[decl.constexpr] p6 in the C++ standard says:

"if no argument values exist such that an invocation of the function or
constructor could be an evaluated subexpression of a core constant expressi=
on
[...] the program is ill-formed, no diagnostic required."

So the foo() function is ill-formed, but implementations are not required to
diagnose it unless the function is actually evaluated.

So this is not accepts-invalid, but I'll confirm it as a request for a
diagnostic enhancement.=