[libc++] Remove <locale> includes from <format> (#85478)

This reduces the include time from 767ms to 691ms.

11 files changed, 65 insertions, 8 deletions

diff --git a/libcxx/include/__format/format_context.h b/libcxx/include/__format/format_context.h
index d131e94..bf603c5 100644
--- a/libcxx/include/__format/format_context.h
+++ b/libcxx/include/__format/format_context.h
@@ -27,7 +27,7 @@
 #include <cstddef>
 
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
-#  include <locale>
+#  include <__locale>
 #  include <optional>
 #endif
 
diff --git a/libcxx/include/__format/format_functions.h b/libcxx/include/__format/format_functions.h
index 3ee5353..c781014 100644
--- a/libcxx/include/__format/format_functions.h
+++ b/libcxx/include/__format/format_functions.h
@@ -41,7 +41,7 @@
 #include <string_view>
 
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
-#  include <locale>
+#  include <__locale>
 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/__format/formatter_floating_point.h b/libcxx/include/__format/formatter_floating_point.h
index f01d323..1d94cc3 100644
--- a/libcxx/include/__format/formatter_floating_point.h
+++ b/libcxx/include/__format/formatter_floating_point.h
@@ -39,7 +39,7 @@
 #include <cstddef>
 
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
-#  include <locale>
+#  include <__locale>
 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/format b/libcxx/include/format
index c0485c5..1466134 100644
--- a/libcxx/include/format
+++ b/libcxx/include/format
@@ -221,4 +221,8 @@ namespace std {
 #  pragma GCC system_header
 #endif
 
+#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
+#  include <locale>
+#endif
+
 #endif // _LIBCPP_FORMAT
diff --git a/libcxx/test/libcxx/transitive_includes/cxx03.csv b/libcxx/test/libcxx/transitive_includes/cxx03.csv
index 678a986..c65b9b9 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx03.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx03.csv
@@ -266,9 +266,14 @@ filesystem system_error
 filesystem type_traits
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
 format locale
diff --git a/libcxx/test/libcxx/transitive_includes/cxx11.csv b/libcxx/test/libcxx/transitive_includes/cxx11.csv
index c3875fa2..b3d9e32 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx11.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx11.csv
@@ -267,9 +267,14 @@ filesystem system_error
 filesystem type_traits
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
 format locale
diff --git a/libcxx/test/libcxx/transitive_includes/cxx14.csv b/libcxx/test/libcxx/transitive_includes/cxx14.csv
index e28e0cd..d723409 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx14.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx14.csv
@@ -269,9 +269,14 @@ filesystem system_error
 filesystem type_traits
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
 format locale
diff --git a/libcxx/test/libcxx/transitive_includes/cxx17.csv b/libcxx/test/libcxx/transitive_includes/cxx17.csv
index e28e0cd..d723409 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx17.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx17.csv
@@ -269,9 +269,14 @@ filesystem system_error
 filesystem type_traits
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
 format locale
diff --git a/libcxx/test/libcxx/transitive_includes/cxx20.csv b/libcxx/test/libcxx/transitive_includes/cxx20.csv
index eec71f4..b355e7b 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx20.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx20.csv
@@ -113,17 +113,21 @@ charconv type_traits
 charconv version
 chrono array
 chrono bit
+chrono cctype
+chrono cerrno
 chrono charconv
+chrono clocale
 chrono cmath
 chrono compare
 chrono concepts
 chrono cstddef
 chrono cstdint
+chrono cstdlib
 chrono cstring
 chrono ctime
+chrono cwchar
 chrono forward_list
 chrono limits
-chrono locale
 chrono optional
 chrono ostream
 chrono ratio
@@ -275,9 +279,14 @@ filesystem system_error
 filesystem type_traits
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
 format locale
diff --git a/libcxx/test/libcxx/transitive_includes/cxx23.csv b/libcxx/test/libcxx/transitive_includes/cxx23.csv
index ccba100..8150f09 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx23.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx23.csv
@@ -68,15 +68,20 @@ charconv limits
 charconv new
 charconv version
 chrono array
+chrono cctype
+chrono cerrno
+chrono clocale
 chrono cmath
 chrono compare
 chrono cstddef
 chrono cstdint
+chrono cstdlib
+chrono cstring
 chrono ctime
+chrono cwchar
 chrono forward_list
 chrono initializer_list
 chrono limits
-chrono locale
 chrono new
 chrono optional
 chrono ostream
@@ -85,6 +90,8 @@ chrono sstream
 chrono stdexcept
 chrono string
 chrono string_view
+chrono tuple
+chrono typeinfo
 chrono vector
 chrono version
 cinttypes cstdint
@@ -184,12 +191,16 @@ filesystem string
 filesystem string_view
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
-format locale
 format new
 format optional
 format queue
@@ -198,6 +209,7 @@ format stdexcept
 format string
 format string_view
 format tuple
+format typeinfo
 format version
 forward_list compare
 forward_list cstddef
diff --git a/libcxx/test/libcxx/transitive_includes/cxx26.csv b/libcxx/test/libcxx/transitive_includes/cxx26.csv
index ccba100..8150f09 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx26.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx26.csv
@@ -68,15 +68,20 @@ charconv limits
 charconv new
 charconv version
 chrono array
+chrono cctype
+chrono cerrno
+chrono clocale
 chrono cmath
 chrono compare
 chrono cstddef
 chrono cstdint
+chrono cstdlib
+chrono cstring
 chrono ctime
+chrono cwchar
 chrono forward_list
 chrono initializer_list
 chrono limits
-chrono locale
 chrono new
 chrono optional
 chrono ostream
@@ -85,6 +90,8 @@ chrono sstream
 chrono stdexcept
 chrono string
 chrono string_view
+chrono tuple
+chrono typeinfo
 chrono vector
 chrono version
 cinttypes cstdint
@@ -184,12 +191,16 @@ filesystem string
 filesystem string_view
 filesystem version
 format array
+format cctype
+format clocale
 format cmath
 format cstddef
 format cstdint
+format cstdlib
+format cstring
+format cwchar
 format initializer_list
 format limits
-format locale
 format new
 format optional
 format queue
@@ -198,6 +209,7 @@ format stdexcept
 format string
 format string_view
 format tuple
+format typeinfo
 format version
 forward_list compare
 forward_list cstddef