[clang] [clang][docs] assert.h is not a good candidate for a textual header (PR #165057)

[Ian Anderson via cfe-commits]

ian-twilightcoder wrote:

Maybe this is a bigger discussion than this PR. Maybe we should just leave with "it's complicated" and not talk about assert.h at all in the documentation?

https://github.com/llvm/llvm-project/pull/165057