[libc++][RFC] Only include what is required by-version in the umbrella headers #83740

philnik777 · 2024-03-03T19:39:31Z

This is a relatively low cost way of reducing the include sizes in older language modes compared to the effect. For example, in C++14 mode the include time of <algorithm> is reduced from 198ms to 127ms.

philnik777 · 2024-03-03T19:43:50Z

@mordante @ldionne What are your thoughts on this?

llvmbot · 2024-03-03T19:44:13Z

@llvm/pr-subscribers-libcxx

Author: Nikolas Klauser (philnik777)

Changes

This is a relatively low cost way of reducing the include sizes in older language modes compared to the effect. For example, in C++14 mode the include time of <algorithm> is reduced from 198ms to 127ms.

Patch is 28.70 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/83740.diff

14 Files Affected:

(modified) libcxx/include/algorithm (+213-207)
(modified) libcxx/include/bit (+18-13)
(modified) libcxx/include/charconv (+13-11)
(modified) libcxx/include/chrono (+24-20)
(modified) libcxx/include/compare (+16-13)
(modified) libcxx/include/concepts (+25-22)
(modified) libcxx/include/coroutine (+4)
(modified) libcxx/include/module.modulemap.in (+4-1)
(modified) libcxx/include/streambuf (+1)
(modified) libcxx/test/libcxx/algorithms/half_positive.pass.cpp (+2-2)
(modified) libcxx/test/libcxx/time/convert_to_tm.pass.cpp (+1)
(modified) libcxx/test/libcxx/transitive_includes/cxx03.csv (-1)
(modified) libcxx/test/libcxx/transitive_includes/cxx11.csv (-1)
(modified) libcxx/test/tools/clang_tidy_checks/CMakeLists.txt (+1-1)

diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 0f62de7fa83f98..39f24efafe0755 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -1796,213 +1796,219 @@ template <class BidirectionalIterator, class Compare>
 #include <__config>
 #include <version>
 
-#include <__algorithm/adjacent_find.h>
-#include <__algorithm/all_of.h>
-#include <__algorithm/any_of.h>
-#include <__algorithm/binary_search.h>
-#include <__algorithm/clamp.h>
-#include <__algorithm/comp.h>
-#include <__algorithm/comp_ref_type.h>
-#include <__algorithm/copy.h>
-#include <__algorithm/copy_backward.h>
-#include <__algorithm/copy_if.h>
-#include <__algorithm/copy_n.h>
-#include <__algorithm/count.h>
-#include <__algorithm/count_if.h>
-#include <__algorithm/equal.h>
-#include <__algorithm/equal_range.h>
-#include <__algorithm/fill.h>
-#include <__algorithm/fill_n.h>
-#include <__algorithm/find.h>
-#include <__algorithm/find_end.h>
-#include <__algorithm/find_first_of.h>
-#include <__algorithm/find_if.h>
-#include <__algorithm/find_if_not.h>
-#include <__algorithm/fold.h>
-#include <__algorithm/for_each.h>
-#include <__algorithm/for_each_n.h>
-#include <__algorithm/generate.h>
-#include <__algorithm/generate_n.h>
-#include <__algorithm/half_positive.h>
-#include <__algorithm/in_found_result.h>
-#include <__algorithm/in_fun_result.h>
-#include <__algorithm/in_in_out_result.h>
-#include <__algorithm/in_in_result.h>
-#include <__algorithm/in_out_out_result.h>
-#include <__algorithm/in_out_result.h>
-#include <__algorithm/includes.h>
-#include <__algorithm/inplace_merge.h>
-#include <__algorithm/is_heap.h>
-#include <__algorithm/is_heap_until.h>
-#include <__algorithm/is_partitioned.h>
-#include <__algorithm/is_permutation.h>
-#include <__algorithm/is_sorted.h>
-#include <__algorithm/is_sorted_until.h>
-#include <__algorithm/iter_swap.h>
-#include <__algorithm/lexicographical_compare.h>
-#include <__algorithm/lexicographical_compare_three_way.h>
-#include <__algorithm/lower_bound.h>
-#include <__algorithm/make_heap.h>
-#include <__algorithm/max.h>
-#include <__algorithm/max_element.h>
-#include <__algorithm/merge.h>
-#include <__algorithm/min.h>
-#include <__algorithm/min_element.h>
-#include <__algorithm/min_max_result.h>
-#include <__algorithm/minmax.h>
-#include <__algorithm/minmax_element.h>
-#include <__algorithm/mismatch.h>
-#include <__algorithm/move.h>
-#include <__algorithm/move_backward.h>
-#include <__algorithm/next_permutation.h>
-#include <__algorithm/none_of.h>
-#include <__algorithm/nth_element.h>
-#include <__algorithm/partial_sort.h>
-#include <__algorithm/partial_sort_copy.h>
-#include <__algorithm/partition.h>
-#include <__algorithm/partition_copy.h>
-#include <__algorithm/partition_point.h>
-#include <__algorithm/pop_heap.h>
-#include <__algorithm/prev_permutation.h>
-#include <__algorithm/pstl_any_all_none_of.h>
-#include <__algorithm/pstl_copy.h>
-#include <__algorithm/pstl_count.h>
-#include <__algorithm/pstl_equal.h>
-#include <__algorithm/pstl_fill.h>
-#include <__algorithm/pstl_find.h>
-#include <__algorithm/pstl_for_each.h>
-#include <__algorithm/pstl_generate.h>
-#include <__algorithm/pstl_is_partitioned.h>
-#include <__algorithm/pstl_merge.h>
-#include <__algorithm/pstl_move.h>
-#include <__algorithm/pstl_replace.h>
-#include <__algorithm/pstl_rotate_copy.h>
-#include <__algorithm/pstl_sort.h>
-#include <__algorithm/pstl_stable_sort.h>
-#include <__algorithm/pstl_transform.h>
-#include <__algorithm/push_heap.h>
-#include <__algorithm/ranges_adjacent_find.h>
-#include <__algorithm/ranges_all_of.h>
-#include <__algorithm/ranges_any_of.h>
-#include <__algorithm/ranges_binary_search.h>
-#include <__algorithm/ranges_clamp.h>
-#include <__algorithm/ranges_contains.h>
-#include <__algorithm/ranges_contains_subrange.h>
-#include <__algorithm/ranges_copy.h>
-#include <__algorithm/ranges_copy_backward.h>
-#include <__algorithm/ranges_copy_if.h>
-#include <__algorithm/ranges_copy_n.h>
-#include <__algorithm/ranges_count.h>
-#include <__algorithm/ranges_count_if.h>
-#include <__algorithm/ranges_ends_with.h>
-#include <__algorithm/ranges_equal.h>
-#include <__algorithm/ranges_equal_range.h>
-#include <__algorithm/ranges_fill.h>
-#include <__algorithm/ranges_fill_n.h>
-#include <__algorithm/ranges_find.h>
-#include <__algorithm/ranges_find_end.h>
-#include <__algorithm/ranges_find_first_of.h>
-#include <__algorithm/ranges_find_if.h>
-#include <__algorithm/ranges_find_if_not.h>
-#include <__algorithm/ranges_for_each.h>
-#include <__algorithm/ranges_for_each_n.h>
-#include <__algorithm/ranges_generate.h>
-#include <__algorithm/ranges_generate_n.h>
-#include <__algorithm/ranges_includes.h>
-#include <__algorithm/ranges_inplace_merge.h>
-#include <__algorithm/ranges_is_heap.h>
-#include <__algorithm/ranges_is_heap_until.h>
-#include <__algorithm/ranges_is_partitioned.h>
-#include <__algorithm/ranges_is_permutation.h>
-#include <__algorithm/ranges_is_sorted.h>
-#include <__algorithm/ranges_is_sorted_until.h>
-#include <__algorithm/ranges_lexicographical_compare.h>
-#include <__algorithm/ranges_lower_bound.h>
-#include <__algorithm/ranges_make_heap.h>
-#include <__algorithm/ranges_max.h>
-#include <__algorithm/ranges_max_element.h>
-#include <__algorithm/ranges_merge.h>
-#include <__algorithm/ranges_min.h>
-#include <__algorithm/ranges_min_element.h>
-#include <__algorithm/ranges_minmax.h>
-#include <__algorithm/ranges_minmax_element.h>
-#include <__algorithm/ranges_mismatch.h>
-#include <__algorithm/ranges_move.h>
-#include <__algorithm/ranges_move_backward.h>
-#include <__algorithm/ranges_next_permutation.h>
-#include <__algorithm/ranges_none_of.h>
-#include <__algorithm/ranges_nth_element.h>
-#include <__algorithm/ranges_partial_sort.h>
-#include <__algorithm/ranges_partial_sort_copy.h>
-#include <__algorithm/ranges_partition.h>
-#include <__algorithm/ranges_partition_copy.h>
-#include <__algorithm/ranges_partition_point.h>
-#include <__algorithm/ranges_pop_heap.h>
-#include <__algorithm/ranges_prev_permutation.h>
-#include <__algorithm/ranges_push_heap.h>
-#include <__algorithm/ranges_remove.h>
-#include <__algorithm/ranges_remove_copy.h>
-#include <__algorithm/ranges_remove_copy_if.h>
-#include <__algorithm/ranges_remove_if.h>
-#include <__algorithm/ranges_replace.h>
-#include <__algorithm/ranges_replace_copy.h>
-#include <__algorithm/ranges_replace_copy_if.h>
-#include <__algorithm/ranges_replace_if.h>
-#include <__algorithm/ranges_reverse.h>
-#include <__algorithm/ranges_reverse_copy.h>
-#include <__algorithm/ranges_rotate.h>
-#include <__algorithm/ranges_rotate_copy.h>
-#include <__algorithm/ranges_sample.h>
-#include <__algorithm/ranges_search.h>
-#include <__algorithm/ranges_search_n.h>
-#include <__algorithm/ranges_set_difference.h>
-#include <__algorithm/ranges_set_intersection.h>
-#include <__algorithm/ranges_set_symmetric_difference.h>
-#include <__algorithm/ranges_set_union.h>
-#include <__algorithm/ranges_shuffle.h>
-#include <__algorithm/ranges_sort.h>
-#include <__algorithm/ranges_sort_heap.h>
-#include <__algorithm/ranges_stable_partition.h>
-#include <__algorithm/ranges_stable_sort.h>
-#include <__algorithm/ranges_starts_with.h>
-#include <__algorithm/ranges_swap_ranges.h>
-#include <__algorithm/ranges_transform.h>
-#include <__algorithm/ranges_unique.h>
-#include <__algorithm/ranges_unique_copy.h>
-#include <__algorithm/ranges_upper_bound.h>
-#include <__algorithm/remove.h>
-#include <__algorithm/remove_copy.h>
-#include <__algorithm/remove_copy_if.h>
-#include <__algorithm/remove_if.h>
-#include <__algorithm/replace.h>
-#include <__algorithm/replace_copy.h>
-#include <__algorithm/replace_copy_if.h>
-#include <__algorithm/replace_if.h>
-#include <__algorithm/reverse.h>
-#include <__algorithm/reverse_copy.h>
-#include <__algorithm/rotate.h>
-#include <__algorithm/rotate_copy.h>
-#include <__algorithm/sample.h>
-#include <__algorithm/search.h>
-#include <__algorithm/search_n.h>
-#include <__algorithm/set_difference.h>
-#include <__algorithm/set_intersection.h>
-#include <__algorithm/set_symmetric_difference.h>
-#include <__algorithm/set_union.h>
-#include <__algorithm/shift_left.h>
-#include <__algorithm/shift_right.h>
-#include <__algorithm/shuffle.h>
-#include <__algorithm/sift_down.h>
-#include <__algorithm/sort.h>
-#include <__algorithm/sort_heap.h>
-#include <__algorithm/stable_partition.h>
-#include <__algorithm/stable_sort.h>
-#include <__algorithm/swap_ranges.h>
-#include <__algorithm/transform.h>
-#include <__algorithm/unique.h>
-#include <__algorithm/unique_copy.h>
-#include <__algorithm/unwrap_iter.h>
-#include <__algorithm/upper_bound.h>
+#if 1 // C++03/11
+#  include <__algorithm/adjacent_find.h>
+#  include <__algorithm/all_of.h>
+#  include <__algorithm/any_of.h>
+#  include <__algorithm/binary_search.h>
+#  include <__algorithm/copy.h>
+#  include <__algorithm/copy_backward.h>
+#  include <__algorithm/copy_if.h>
+#  include <__algorithm/copy_n.h>
+#  include <__algorithm/count.h>
+#  include <__algorithm/count_if.h>
+#  include <__algorithm/equal.h>
+#  include <__algorithm/equal_range.h>
+#  include <__algorithm/fill.h>
+#  include <__algorithm/fill_n.h>
+#  include <__algorithm/find.h>
+#  include <__algorithm/find_end.h>
+#  include <__algorithm/find_first_of.h>
+#  include <__algorithm/find_if.h>
+#  include <__algorithm/find_if_not.h>
+#  include <__algorithm/for_each.h>
+#  include <__algorithm/generate.h>
+#  include <__algorithm/generate_n.h>
+#  include <__algorithm/includes.h>
+#  include <__algorithm/inplace_merge.h>
+#  include <__algorithm/is_heap.h>
+#  include <__algorithm/is_heap_until.h>
+#  include <__algorithm/is_partitioned.h>
+#  include <__algorithm/is_permutation.h>
+#  include <__algorithm/is_sorted.h>
+#  include <__algorithm/is_sorted_until.h>
+#  include <__algorithm/iter_swap.h>
+#  include <__algorithm/lexicographical_compare.h>
+#  include <__algorithm/lower_bound.h>
+#  include <__algorithm/make_heap.h>
+#  include <__algorithm/max.h>
+#  include <__algorithm/max_element.h>
+#  include <__algorithm/merge.h>
+#  include <__algorithm/min.h>
+#  include <__algorithm/min_element.h>
+#  include <__algorithm/minmax.h>
+#  include <__algorithm/minmax_element.h>
+#  include <__algorithm/mismatch.h>
+#  include <__algorithm/move.h>
+#  include <__algorithm/move_backward.h>
+#  include <__algorithm/next_permutation.h>
+#  include <__algorithm/none_of.h>
+#  include <__algorithm/nth_element.h>
+#  include <__algorithm/partial_sort.h>
+#  include <__algorithm/partial_sort_copy.h>
+#  include <__algorithm/partition.h>
+#  include <__algorithm/partition_copy.h>
+#  include <__algorithm/partition_point.h>
+#  include <__algorithm/pop_heap.h>
+#  include <__algorithm/prev_permutation.h>
+#  include <__algorithm/push_heap.h>
+#  include <__algorithm/remove.h>
+#  include <__algorithm/remove_copy.h>
+#  include <__algorithm/remove_copy_if.h>
+#  include <__algorithm/remove_if.h>
+#  include <__algorithm/replace.h>
+#  include <__algorithm/replace_copy.h>
+#  include <__algorithm/replace_copy_if.h>
+#  include <__algorithm/replace_if.h>
+#  include <__algorithm/reverse.h>
+#  include <__algorithm/reverse_copy.h>
+#  include <__algorithm/rotate.h>
+#  include <__algorithm/rotate_copy.h>
+#  include <__algorithm/search.h>
+#  include <__algorithm/search_n.h>
+#  include <__algorithm/set_difference.h>
+#  include <__algorithm/set_intersection.h>
+#  include <__algorithm/set_symmetric_difference.h>
+#  include <__algorithm/set_union.h>
+#  include <__algorithm/shuffle.h>
+#  include <__algorithm/sort.h>
+#  include <__algorithm/sort_heap.h>
+#  include <__algorithm/stable_partition.h>
+#  include <__algorithm/stable_sort.h>
+#  include <__algorithm/swap_ranges.h>
+#  include <__algorithm/transform.h>
+#  include <__algorithm/unique.h>
+#  include <__algorithm/unique_copy.h>
+#  include <__algorithm/upper_bound.h>
+#endif // 1 // C++03/11
+
+#if _LIBCPP_STD_VER >= 17
+#  include <__algorithm/clamp.h>
+#  include <__algorithm/for_each_n.h>
+#  include <__algorithm/pstl_any_all_none_of.h>
+#  include <__algorithm/pstl_copy.h>
+#  include <__algorithm/pstl_count.h>
+#  include <__algorithm/pstl_equal.h>
+#  include <__algorithm/pstl_fill.h>
+#  include <__algorithm/pstl_find.h>
+#  include <__algorithm/pstl_for_each.h>
+#  include <__algorithm/pstl_generate.h>
+#  include <__algorithm/pstl_is_partitioned.h>
+#  include <__algorithm/pstl_merge.h>
+#  include <__algorithm/pstl_move.h>
+#  include <__algorithm/pstl_replace.h>
+#  include <__algorithm/pstl_rotate_copy.h>
+#  include <__algorithm/pstl_sort.h>
+#  include <__algorithm/pstl_stable_sort.h>
+#  include <__algorithm/pstl_transform.h>
+#  include <__algorithm/sample.h>
+#endif // _LIBCPP_STD_VER >= 17
+
+#if _LIBCPP_STD_VER >= 20
+#  include <__algorithm/in_found_result.h>
+#  include <__algorithm/in_fun_result.h>
+#  include <__algorithm/in_in_out_result.h>
+#  include <__algorithm/in_in_result.h>
+#  include <__algorithm/in_out_out_result.h>
+#  include <__algorithm/in_out_result.h>
+#  include <__algorithm/lexicographical_compare_three_way.h>
+#  include <__algorithm/min_max_result.h>
+#  include <__algorithm/ranges_adjacent_find.h>
+#  include <__algorithm/ranges_all_of.h>
+#  include <__algorithm/ranges_any_of.h>
+#  include <__algorithm/ranges_binary_search.h>
+#  include <__algorithm/ranges_clamp.h>
+#  include <__algorithm/ranges_contains.h>
+#  include <__algorithm/ranges_copy.h>
+#  include <__algorithm/ranges_copy_backward.h>
+#  include <__algorithm/ranges_copy_if.h>
+#  include <__algorithm/ranges_copy_n.h>
+#  include <__algorithm/ranges_count.h>
+#  include <__algorithm/ranges_count_if.h>
+#  include <__algorithm/ranges_equal.h>
+#  include <__algorithm/ranges_equal_range.h>
+#  include <__algorithm/ranges_fill.h>
+#  include <__algorithm/ranges_fill_n.h>
+#  include <__algorithm/ranges_find.h>
+#  include <__algorithm/ranges_find_end.h>
+#  include <__algorithm/ranges_find_first_of.h>
+#  include <__algorithm/ranges_find_if.h>
+#  include <__algorithm/ranges_find_if_not.h>
+#  include <__algorithm/ranges_for_each.h>
+#  include <__algorithm/ranges_for_each_n.h>
+#  include <__algorithm/ranges_generate.h>
+#  include <__algorithm/ranges_generate_n.h>
+#  include <__algorithm/ranges_includes.h>
+#  include <__algorithm/ranges_inplace_merge.h>
+#  include <__algorithm/ranges_is_heap.h>
+#  include <__algorithm/ranges_is_heap_until.h>
+#  include <__algorithm/ranges_is_partitioned.h>
+#  include <__algorithm/ranges_is_permutation.h>
+#  include <__algorithm/ranges_is_sorted.h>
+#  include <__algorithm/ranges_is_sorted_until.h>
+#  include <__algorithm/ranges_lexicographical_compare.h>
+#  include <__algorithm/ranges_lower_bound.h>
+#  include <__algorithm/ranges_make_heap.h>
+#  include <__algorithm/ranges_max.h>
+#  include <__algorithm/ranges_max_element.h>
+#  include <__algorithm/ranges_merge.h>
+#  include <__algorithm/ranges_min.h>
+#  include <__algorithm/ranges_min_element.h>
+#  include <__algorithm/ranges_minmax.h>
+#  include <__algorithm/ranges_minmax_element.h>
+#  include <__algorithm/ranges_mismatch.h>
+#  include <__algorithm/ranges_move.h>
+#  include <__algorithm/ranges_move_backward.h>
+#  include <__algorithm/ranges_next_permutation.h>
+#  include <__algorithm/ranges_none_of.h>
+#  include <__algorithm/ranges_nth_element.h>
+#  include <__algorithm/ranges_partial_sort.h>
+#  include <__algorithm/ranges_partial_sort_copy.h>
+#  include <__algorithm/ranges_partition.h>
+#  include <__algorithm/ranges_partition_copy.h>
+#  include <__algorithm/ranges_partition_point.h>
+#  include <__algorithm/ranges_pop_heap.h>
+#  include <__algorithm/ranges_prev_permutation.h>
+#  include <__algorithm/ranges_push_heap.h>
+#  include <__algorithm/ranges_remove.h>
+#  include <__algorithm/ranges_remove_copy.h>
+#  include <__algorithm/ranges_remove_copy_if.h>
+#  include <__algorithm/ranges_remove_if.h>
+#  include <__algorithm/ranges_replace.h>
+#  include <__algorithm/ranges_replace_copy.h>
+#  include <__algorithm/ranges_replace_copy_if.h>
+#  include <__algorithm/ranges_replace_if.h>
+#  include <__algorithm/ranges_reverse.h>
+#  include <__algorithm/ranges_reverse_copy.h>
+#  include <__algorithm/ranges_rotate.h>
+#  include <__algorithm/ranges_rotate_copy.h>
+#  include <__algorithm/ranges_sample.h>
+#  include <__algorithm/ranges_search.h>
+#  include <__algorithm/ranges_search_n.h>
+#  include <__algorithm/ranges_set_difference.h>
+#  include <__algorithm/ranges_set_intersection.h>
+#  include <__algorithm/ranges_set_symmetric_difference.h>
+#  include <__algorithm/ranges_set_union.h>
+#  include <__algorithm/ranges_shuffle.h>
+#  include <__algorithm/ranges_sort.h>
+#  include <__algorithm/ranges_sort_heap.h>
+#  include <__algorithm/ranges_stable_partition.h>
+#  include <__algorithm/ranges_stable_sort.h>
+#  include <__algorithm/ranges_swap_ranges.h>
+#  include <__algorithm/ranges_transform.h>
+#  include <__algorithm/ranges_unique.h>
+#  include <__algorithm/ranges_unique_copy.h>
+#  include <__algorithm/ranges_upper_bound.h>
+#  include <__algorithm/shift_left.h>
+#  include <__algorithm/shift_right.h>
+#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_starts_with.h>
+#endif // _LIBCPP_STD_VER >= 23
 
 // standard-mandated includes
 
diff --git a/libcxx/include/bit b/libcxx/include/bit
index b8e4bdc2dfe202..a40c44a3d4a8b6 100644
--- a/libcxx/include/bit
+++ b/libcxx/include/bit
@@ -61,19 +61,24 @@ namespace std {
 
 */
 
-#include <__bit/bit_cast.h>
-#include <__bit/bit_ceil.h>
-#include <__bit/bit_floor.h>
-#include <__bit/bit_log2.h>
-#include <__bit/bit_width.h>
-#include <__bit/blsr.h>
-#include <__bit/byteswap.h>
-#include <__bit/countl.h>
-#include <__bit/countr.h>
-#include <__bit/endian.h>
-#include <__bit/has_single_bit.h>
-#include <__bit/popcount.h>
-#include <__bit/rotate.h>
+#if _LIBCPP_STD_VER >= 20
+#  include <__bit/bit_cast.h>
+#  include <__bit/bit_ceil.h>
+#  include <__bit/bit_floor.h>
+#  include <__bit/bit_log2.h>
+#  include <__bit/bit_width.h>
+#  include <__bit/countl.h>
+#  include <__bit/countr.h>
+#  include <__bit/endian.h>
+#  include <__bit/has_single_bit.h>
+#  include <__bit/popcount.h>
+#  include <__bit/rotate.h>
+#endif
+
+#if _LIBCPP_STD_VER >= 23
+#  include <__bit/byteswap.h>
+#endif
+
 #include <__config>
 #include <version>
 
diff --git a/libcxx/include/charconv b/libcxx/include/charconv
index 5bc7b9011be024..5840f412bad89a 100644
--- a/libcxx/include/charconv
+++ b/libcxx/include/charconv
@@ -69,18 +69,20 @@ namespace std {
 
 */
 
-#include <__charconv/chars_format.h>
-#include <__charconv/from_chars_integral.h>
-#include <__charconv/from_chars_result.h>
-#include <__charconv/tables.h>
-#include <__charconv/to_chars.h>
-#include <__charconv/to_chars_base_10.h>
-#include <__charconv/to_chars_floating_point.h>
-#include <__charconv/to_chars_integral.h>
-#include <__charconv/to_chars_result.h>
-#include <__charconv/traits.h>
+#if _LIBCPP_STD_VER >= 17
+#  include <__charconv/chars_format.h>
+#  include <__charconv/from_chars_integral.h>
+#  include <__charconv/from_chars_result.h>
+#  include <__charconv/tables.h>
+#  include <__charconv/to_chars.h>
+#  include <__charconv/to_chars_base_10.h>
+#  include <__charconv/to_chars_floating_point.h>
+#  include <__charconv/to_chars_integral.h>
+#  include <__charconv/to_chars_result.h>
+#  include <__charconv/traits.h>
+#endif // _LIBCPP_STD_VER >= 17
+
 #include <__config>
-#include <__system_error/errc.h>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
index b3b260c2a998e6..888499c22216de 100644
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -825,26 +825,30 @@ constexpr chrono::year                                  operator ""y(unsigned lo
 
 // clang-format on
 
-#include <__chrono/calendar.h>
-#include <__chrono/convert_to_timespec.h>
-#include <__chrono/convert_to_tm.h>
-#include <__chrono/day.h>
-#include <__chrono/duration.h>
-#include <__chrono/file_clock.h>
-#include <__chrono/hh_mm_ss.h>
-#include <__chrono/high_resolution_clock.h>
-#include <__chrono/literals.h>
-#include <__chrono/month.h>
-#include <__chrono/month_weekday.h>
-#include <__chrono/monthday.h>
-#include <__chrono/steady_clock.h>
-#include <__chrono/system_cl...
[truncated]

mordante

As mentioned earlier I had a patch on Phab with a slightly different approach. So yes in general I like the idea of reducing the size of the includes.

I wonder about the approach you take; your examples only show how to handle granularized headers. I wonder what do you propose for non-granularized headers?

For example, <ostream> includes <print> the <print> header has been introduced in C++23. This header has some includes not used in <ostream>.

Do you propose to keep the <ostream> header unchanged or do you want to guard the include of <print> with C++23?

libcxx/include/bit

libcxx/include/algorithm

libcxx/include/chrono

libcxx/include/module.modulemap.in

libcxx/test/tools/clang_tidy_checks/CMakeLists.txt

philnik777 · 2024-03-07T12:37:55Z

As mentioned earlier I had a patch on Phab with a slightly different approach. So yes in general I like the idea of reducing the size of the includes.

I wonder about the approach you take; your examples only show how to handle granularized headers. I wonder what do you propose for non-granularized headers?

For example, <ostream> includes <print> the <print> header has been introduced in C++23. This header has some includes not used in <ostream>.

Do you propose to keep the <ostream> header unchanged or do you want to guard the include of <print> with C++23?

I propose to either keep them unchanged, or to granularize it if we think it's worth the reduced include size. IIUC the main problem we have is <format> and the different formatter specializations that have to be provided through different headers resulting in huge amounts of transitive includes. Since they can be implemented separately from the rest of the files, we can simply move them into new detail headers and include these detail headers conditionally in the umbrella header.
In essence, I want the only place where we conditionally include headers to be the umbrella headers.

mordante · 2024-03-09T12:12:12Z

As mentioned earlier I had a patch on Phab with a slightly different approach. So yes in general I like the idea of reducing the size of the includes.
I wonder about the approach you take; your examples only show how to handle granularized headers. I wonder what do you propose for non-granularized headers?
For example, <ostream> includes <print> the <print> header has been introduced in C++23. This header has some includes not used in <ostream>.
Do you propose to keep the <ostream> header unchanged or do you want to guard the include of <print> with C++23?

I propose to either keep them unchanged, or to granularize it if we think it's worth the reduced include size. IIUC the main problem we have is <format> and the different formatter specializations that have to be provided through different headers resulting in huge amounts of transitive includes. Since they can be implemented separately from the rest of the files, we can simply move them into new detail headers and include these detail headers conditionally in the umbrella header. In essence, I want the only place where we conditionally include headers to be the umbrella headers.

I'm not sure how feasible splitting-off format would be. For example the formatter for vector needs to know about vector. IMO that is something we can look into for a separate patch if we want to solve these includes.

I think the approach you suggest is simple and easy to maintain. I think we could do more, but that might have an different maintenance trade-off. Taking this approach does not block other optimizations. So I'm happy to move forward with this direction.

ldionne

This direction LGTM. There are a few bugs as pointed out by Mark, but with those fixed I think this patch makes a lot of sense.

libcxx/include/algorithm

…ders

…a headers (llvm#83740) This is a relatively low cost way of reducing the include sizes in older language modes compared to the effect. For example, in C++14 mode the include time of `<algorithm>` is reduced from 198ms to 127ms.

…rella headers (#96032) This is a follow-up to #83740.

…rella headers (#96032) Summary: This is a follow-up to #83740. Test Plan: Reviewers: Subscribers: Tasks: Tags: Differential Revision: https://phabricator.intern.facebook.com/D60250970

philnik777 marked this pull request as ready for review March 3, 2024 19:43

philnik777 requested a review from a team as a code owner March 3, 2024 19:43

llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Mar 3, 2024

philnik777 changed the title ~~[libc++] Only include what is required by-version in the umbrella headers~~ [libc++][RFC] Only include what is required by-version in the umbrella headers Mar 3, 2024

mordante reviewed Mar 4, 2024

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ldionne approved these changes Apr 5, 2024

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philnik777 force-pushed the reduce_include_size branch 2 times, most recently from acf7ea0 to a0cec7f Compare April 13, 2024 16:53

[libc++] Only include what is required by-version in the umbrella hea…

74c6a48

…ders

philnik777 force-pushed the reduce_include_size branch from a0cec7f to 74c6a48 Compare April 14, 2024 06:55

philnik777 merged commit d5c654b into llvm:main Apr 14, 2024

philnik777 deleted the reduce_include_size branch April 14, 2024 13:53

philnik777 mentioned this pull request Jun 19, 2024

[libc++] Include the rest of the detail headers by version in the umbrella headers #96032

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philnik777 added a commit that referenced this pull request Jul 18, 2024

[libc++] Include the rest of the detail headers by version in the umb…

dfddc0c

…rella headers (#96032) This is a follow-up to #83740.

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