constexpr not allowed on member function of type with a virtual base.

[i-photon]

Virtual constexpr has been allowed since C++20.
What happened?

Here's my sentiment: https://godbolt.org/z/f8hYGYMab

This is causing a needless headache trying to re-use interfaces in constexpr.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: None (i-photon)

Virtual constexpr has been allowed since C++20. What happened?

Here's my sentiment: https://godbolt.org/z/f8hYGYMab

This is causing a needless headache trying to re-use interfaces in constexpr.

[llvmbot]

@llvm/issue-subscribers-c-20

Author: None (i-photon)

Virtual constexpr has been allowed since C++20. What happened?

Here's my sentiment: https://godbolt.org/z/f8hYGYMab

This is causing a needless headache trying to re-use interfaces in constexpr.

[cor3ntin]

The restriction only applies to structors https://eel.is/c++draft/dcl.dcl#dcl.constexpr-3

[frederick-vs-ja]

Looks like a duplicate of #97266.

Virtual constexpr has been allowed since C++20.

This is unrelated to virtual base classes.

[PJBoy]

Ran into this myself. Here's a cutdown testcase https://godbolt.org/z/aozcG9f1f
Virtual base classes are allowed all the way back to C++11 for non-ctor/dtors, here's some citations for reference
C++11 https://timsong-cpp.github.io/cppwp/n3337/dcl.constexpr#3
C++23 https://timsong-cpp.github.io/cppwp/n4950/dcl.constexpr#3
Trunk (which no longer has the ctor/dtor condition) https://eel.is/c++draft/dcl.constexpr#3