[clang] [Clang] disallow # operators in attribute argument lists (PR #147308)

[Corentin Jabot via cfe-commits]

cor3ntin wrote:

There is divergence between C and C++, I sent a mail to core https://lists.isocpp.org/liaison/2025/07/1549.php

https://github.com/llvm/llvm-project/pull/147308