[Bug c++/68012] g++ incorrectly accepts forward declaration of constexpr variable template

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68012

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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           Keywords|                            |diagnostic
                 CC|                            |jason at gcc dot gnu.org

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> ---
This seems like an ill-formed, no diagnostic required situation because no
valid specialization can be generated; if you try to instantiate the template,
G++ complains then.  I agree that giving a diagnostic would be better, but the
conformance issue is that G++ allows you to redefine it (PR 92576).