[clang] [clang][Sema] Allow splat initialization of a sizeless vector in a C++ code (PR #205432)

[Benjamin Maxwell via cfe-commits]

https://github.com/MacDue commented:

>From the commit message I'd assumed this was allowing something already supported generally for fixed-length vectors. However, from testing locally, I see we don't allow this for standard NEON types (e.g. https://godbolt.org/z/5bTaq87ve).

With your patch applied these conversions work (and result in splats), but only for SVE types: https://godbolt.org/z/8b59KKGcG

Is this intentional? I'd assumed this was about parity between fixed/scalable types.

https://github.com/llvm/llvm-project/pull/205432