[libcxx-commits] [PATCH] D148405: [libc++] Remove the chrono include from algorithm

[Ian Anderson via Phabricator via libcxx-commits]

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algorithm's include of chrono causes include cycles:

algorithm -> chrono -> __chrono/convert_to_tm.h -> __chrono/statically_widen.h -> __format/concepts.h -> __format/format_parse_context.h -> string_view -> algorithm

algorithm -> chrono -> __chrono/convert_to_tm.h -> __chrono/statically_widen.h -> __format/concepts.h -> __format/format_parse_context.h -> string_view -> functional -> __functional/boyer_moore_searcher.h -> array -> algorithm

algorithm -> chrono -> __chrono/convert_to_tm.h -> __chrono/statically_widen.h -> __format/concepts.h -> __format/format_parse_context.h -> string_view -> functional -> __functional/boyer_moore_searcher.h -> unordered_map -> algorithm

algorithm -> chrono -> __chrono/convert_to_tm.h -> __chrono/statically_widen.h -> __format/concepts.h -> __format/format_parse_context.h -> string_view -> functional -> __functional/boyer_moore_searcher.h -> vector -> algorithm

This is a problem for clang modules after the std mega module is broken up, because it becomes a module cycle which is a hard error.

All of the includes in the __chrono and __format headers are being used and so can't be removed. algorithm's include of chrono is already removed in C++20, whereas the array, string_view, unordered_map, vector includes of algorithm aren't removed until C++23 (and it's 4x the includes that would need removing). Unconditionally remove the chrono include from algorithm in all versions, so that the module breakup can happen (the module has to apply to all C++ versions).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148405

Files:
  libcxx/include/algorithm


Index: libcxx/include/algorithm
===================================================================
--- libcxx/include/algorithm
+++ libcxx/include/algorithm
@@ -1921,10 +1921,6 @@
 #  include <__pstl_algorithm>
 #endif
 
-#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 17
-#  include <chrono>
-#endif
-
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <atomic>
 #  include <bit>


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