[libcxx-commits] [libcxx] [libc++][ranges] optimize the performance of `ranges::starts_with` (PR #84570)

[Louis Dionne via libcxx-commits]

================
@@ -50,14 +54,36 @@ struct __fn {
       _Pred __pred   = {},
       _Proj1 __proj1 = {},
       _Proj2 __proj2 = {}) {
-    return __mismatch::__fn::__go(
+    if constexpr (sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2>) {
----------------
ldionne wrote:

Great, thanks! We don't have a code coverage generator right now. I think it's kinda tricky to do right with template instantiations but it could be worthwhile to have something that works well, if that's possible.

https://github.com/llvm/llvm-project/pull/84570