[Bug c++/97710] New: Help with breaking change? cast point-to-member address in template parameter list

[mick.pearson at wildblue dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97710

            Bug ID: 97710
           Summary: Help with breaking change? cast point-to-member
                    address in template parameter list
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mick.pearson at wildblue dot net
  Target Milestone: ---

GCC used to agree with MSVC in letting pointer-to-member addresses be cast
inside templates, i.e. compile time constants. Cygwin updated me to 10.2.0 and
this now produces an "error: 'reinterpret_cast' is not a constant expression"
diagnostic.

The Clang tracker laughed at a request I made in the past to enable this for
Clang. (Please reach consensus? https://bugs.llvm.org/show_bug.cgi?id=33708) I
doubt Microsoft will break this in future versions of MSVC since that's not
it's style, so I wonder if this is an oversight in GCC, and if not what
recourse exists. 

Thank you, maybe related:
https://patchwork.ozlabs.org/project/gcc/patch/or604puqhd.fsf@lxoliva.fsfla.org/