[libc++][NFC] Rename fold.h to ranges_fold.h (#109696)

This follows the pattern we use consistently for ranges algorithms.

Author: ldionne

libcxx/include/CMakeLists.txt

@@ -23,7 +23,6 @@ set(files
   __algorithm/find_if.h
   __algorithm/find_if_not.h
   __algorithm/find_segment_if.h
-  __algorithm/fold.h
   __algorithm/for_each.h
   __algorithm/for_each_n.h
   __algorithm/for_each_segment.h
@@ -98,6 +97,7 @@ set(files
   __algorithm/ranges_find_if.h
   __algorithm/ranges_find_if_not.h
   __algorithm/ranges_find_last.h
+  __algorithm/ranges_fold.h
   __algorithm/ranges_for_each.h
   __algorithm/ranges_for_each_n.h
   __algorithm/ranges_generate.h

libcxx/include/__algorithm/fold.h renamed to libcxx/include/__algorithm/ranges_fold.h

@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___ALGORITHM_FOLD_H
-#define _LIBCPP___ALGORITHM_FOLD_H
+#ifndef _LIBCPP___ALGORITHM_RANGES_FOLD_H
+#define _LIBCPP___ALGORITHM_RANGES_FOLD_H
 
 #include <__concepts/assignable.h>
 #include <__concepts/constructible.h>
@@ -126,4 +126,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
-#endif // _LIBCPP___ALGORITHM_FOLD_H
+#endif // _LIBCPP___ALGORITHM_RANGES_FOLD_H

libcxx/include/algorithm

@@ -2020,10 +2020,10 @@ template <class BidirectionalIterator, class Compare>
 #endif
 
 #if _LIBCPP_STD_VER >= 23
-#  include <__algorithm/fold.h>
 #  include <__algorithm/ranges_contains_subrange.h>
 #  include <__algorithm/ranges_ends_with.h>
 #  include <__algorithm/ranges_find_last.h>
+#  include <__algorithm/ranges_fold.h>
 #  include <__algorithm/ranges_starts_with.h>
 #endif // _LIBCPP_STD_VER >= 23
 

libcxx/include/module.modulemap

@@ -412,7 +412,6 @@ module std [system] {
     module find_if                                { header "__algorithm/find_if.h" }
     module find_segment_if                        { header "__algorithm/find_segment_if.h" }
     module find                                   { header "__algorithm/find.h" }
-    module fold                                   { header "__algorithm/fold.h" }
     module for_each_n                             { header "__algorithm/for_each_n.h" }
     module for_each_segment                       { header "__algorithm/for_each_segment.h" }
     module for_each                               { header "__algorithm/for_each.h" }
@@ -529,6 +528,7 @@ module std [system] {
     module ranges_find_if                         { header "__algorithm/ranges_find_if.h" }
     module ranges_find_last                       { header "__algorithm/ranges_find_last.h" }
     module ranges_find                            { header "__algorithm/ranges_find.h" }
+    module ranges_fold                            { header "__algorithm/ranges_fold.h" }
     module ranges_for_each_n {
       header "__algorithm/ranges_for_each_n.h"
       export std.algorithm.in_fun_result