[libcxx-commits] [libcxx] [libc++][NFC] Don't use std::distance in std::equal (PR #177113)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Nikolas Klauser (philnik777)

<details>
<summary>Changes</summary>

We don't need to use `std::distance`, since we know for a fact that we have random access iterators in that place. Instead, we can just subtract the iterators, avoiding a bunch of template machinery and imrpoving compile times a bit.


---
Full diff: https://github.com/llvm/llvm-project/pull/177113.diff


1 Files Affected:

- (modified) libcxx/include/__algorithm/equal.h (+1-4) 


``````````diff
diff --git a/libcxx/include/__algorithm/equal.h b/libcxx/include/__algorithm/equal.h
index 753cac5a469e4..ca536dc61e235 100644
--- a/libcxx/include/__algorithm/equal.h
+++ b/libcxx/include/__algorithm/equal.h
@@ -16,15 +16,12 @@
 #include <__config>
 #include <__functional/identity.h>
 #include <__fwd/bit_reference.h>
-#include <__iterator/distance.h>
 #include <__iterator/iterator_traits.h>
-#include <__memory/pointer_traits.h>
 #include <__string/constexpr_c_functions.h>
 #include <__type_traits/desugars_to.h>
 #include <__type_traits/enable_if.h>
 #include <__type_traits/invoke.h>
 #include <__type_traits/is_equality_comparable.h>
-#include <__type_traits/is_same.h>
 #include <__type_traits/is_volatile.h>
 #include <__utility/move.h>
 
@@ -251,7 +248,7 @@ equal(_InputIterator1 __first1,
       __has_random_access_iterator_category<_InputIterator1>::value &&
       __has_random_access_iterator_category<_InputIterator2>::value;
   if constexpr (__both_random_access) {
-    if (std::distance(__first1, __last1) != std::distance(__first2, __last2))
+    if (__last1 - __first1 != __last2 - __first2)
       return false;
   }
   __identity __proj;

``````````

</details>


https://github.com/llvm/llvm-project/pull/177113