[libc++] Remove the type_traits includes from limits and new

type_traits is currently unable to include __type_traits/noexcept_move_assign_container.h, because it would cause several include cycles.

type_traits -> __type_traits/noexcept_move_assign_container.h -> __memory/allocator_traits.h -> __memory/construct_at.h -> new -> exception -> type_traits

type_traits -> __type_traits/noexcept_move_assign_container.h -> __memory/allocator_traits.h -> __memory/construct_at.h -> new -> type_traits

type_traits -> __type_traits/noexcept_move_assign_container.h -> __memory/allocator_traits.h -> limits -> type_traits

This is a problem for clang modules after the std mega module is broken up (D144322), because it becomes a module cycle which is a hard error.

Unconditionally remove the type_traits includes from limits and new in all versions, and also remove the exception include from new. (These are already removed in C++23.)

Reviewed By: ldionne, Mordante, #libc

Differential Revision: https://reviews.llvm.org/D153214

libcxx/docs/ReleaseNotes.rst

@@ -83,6 +83,10 @@ Deprecations and Removals
 
 - ``<algorithm>`` no longer includes ``<chrono>`` in any C++ version (it was previously included in C++17 and earlier).
 
+- ``<limits>`` no longer includes ``<type_traits>`` in any C++ version (it was previously included in C++20 and earlier).
+
+- ``<new>`` no longer includes ``<exception>`` or ``<type_traits>`` in any C++ version (they were previously included in C++20 and earlier).
+
 - ``<string>`` no longer includes ``<vector>`` in any C++ version (it was previously included in C++20 and earlier).
 
 - ``<string>``, ``<string_view>``, and ``<mutex>`` no longer include ``<functional>``

libcxx/include/limits

@@ -823,8 +823,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
-#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
-#  include <type_traits>
-#endif
-
 #endif // _LIBCPP_LIMITS

libcxx/include/new

@@ -365,9 +365,4 @@ inline constexpr size_t hardware_constructive_interference_size = __GCC_CONSTRUC
 
 _LIBCPP_END_NAMESPACE_STD
 
-#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
-#  include <exception>
-#  include <type_traits>
-#endif
-
 #endif // _LIBCPP_NEW

libcxx/test/libcxx/transitive_includes/cxx03.csv

@@ -456,7 +456,6 @@ latch limits
 latch ratio
 latch type_traits
 latch version
-limits type_traits
 limits version
 list algorithm
 list atomic
@@ -571,8 +570,6 @@ mutex typeinfo
 mutex version
 new cstddef
 new cstdlib
-new exception
-new type_traits
 new version
 numbers concepts
 numbers type_traits
@@ -639,6 +636,7 @@ ostream version
 queue compare
 queue concepts
 queue cstddef
+queue cstdint
 queue cstdlib
 queue deque
 queue functional
@@ -774,6 +772,7 @@ sstream version
 stack compare
 stack concepts
 stack cstddef
+stack cstdint
 stack deque
 stack functional
 stack initializer_list
@@ -936,6 +935,7 @@ valarray algorithm
 valarray cmath
 valarray concepts
 valarray cstddef
+valarray cstdint
 valarray cstdlib
 valarray cstring
 valarray functional

libcxx/test/libcxx/transitive_includes/cxx11.csv

@@ -456,7 +456,6 @@ latch limits
 latch ratio
 latch type_traits
 latch version
-limits type_traits
 limits version
 list algorithm
 list atomic
@@ -572,8 +571,6 @@ mutex typeinfo
 mutex version
 new cstddef
 new cstdlib
-new exception
-new type_traits
 new version
 numbers concepts
 numbers type_traits
@@ -640,6 +637,7 @@ ostream version
 queue compare
 queue concepts
 queue cstddef
+queue cstdint
 queue cstdlib
 queue deque
 queue functional
@@ -775,6 +773,7 @@ sstream version
 stack compare
 stack concepts
 stack cstddef
+stack cstdint
 stack deque
 stack functional
 stack initializer_list
@@ -937,6 +936,7 @@ valarray algorithm
 valarray cmath
 valarray concepts
 valarray cstddef
+valarray cstdint
 valarray cstdlib
 valarray cstring
 valarray functional

libcxx/test/libcxx/transitive_includes/cxx14.csv

@@ -458,7 +458,6 @@ latch limits
 latch ratio
 latch type_traits
 latch version
-limits type_traits
 limits version
 list algorithm
 list atomic
@@ -574,8 +573,6 @@ mutex typeinfo
 mutex version
 new cstddef
 new cstdlib
-new exception
-new type_traits
 new version
 numbers concepts
 numbers type_traits
@@ -642,6 +639,7 @@ ostream version
 queue compare
 queue concepts
 queue cstddef
+queue cstdint
 queue cstdlib
 queue deque
 queue functional
@@ -777,6 +775,7 @@ sstream version
 stack compare
 stack concepts
 stack cstddef
+stack cstdint
 stack deque
 stack functional
 stack initializer_list
@@ -939,6 +938,7 @@ valarray algorithm
 valarray cmath
 valarray concepts
 valarray cstddef
+valarray cstdint
 valarray cstdlib
 valarray cstring
 valarray functional

libcxx/test/libcxx/transitive_includes/cxx17.csv

@@ -458,7 +458,6 @@ latch limits
 latch ratio
 latch type_traits
 latch version
-limits type_traits
 limits version
 list algorithm
 list atomic
@@ -574,8 +573,6 @@ mutex typeinfo
 mutex version
 new cstddef
 new cstdlib
-new exception
-new type_traits
 new version
 numbers concepts
 numbers type_traits
@@ -642,6 +639,7 @@ ostream version
 queue compare
 queue concepts
 queue cstddef
+queue cstdint
 queue cstdlib
 queue deque
 queue functional
@@ -777,6 +775,7 @@ sstream version
 stack compare
 stack concepts
 stack cstddef
+stack cstdint
 stack deque
 stack functional
 stack initializer_list
@@ -939,6 +938,7 @@ valarray algorithm
 valarray cmath
 valarray concepts
 valarray cstddef
+valarray cstdint
 valarray cstdlib
 valarray cstring
 valarray functional

libcxx/test/libcxx/transitive_includes/cxx20.csv

@@ -464,7 +464,6 @@ latch limits
 latch ratio
 latch type_traits
 latch version
-limits type_traits
 limits version
 list algorithm
 list atomic
@@ -580,8 +579,6 @@ mutex typeinfo
 mutex version
 new cstddef
 new cstdlib
-new exception
-new type_traits
 new version
 numbers concepts
 numbers type_traits
@@ -648,6 +645,7 @@ ostream version
 queue compare
 queue concepts
 queue cstddef
+queue cstdint
 queue cstdlib
 queue deque
 queue functional
@@ -783,6 +781,7 @@ sstream version
 stack compare
 stack concepts
 stack cstddef
+stack cstdint
 stack deque
 stack functional
 stack initializer_list
@@ -944,6 +943,7 @@ valarray algorithm
 valarray cmath
 valarray concepts
 valarray cstddef
+valarray cstdint
 valarray cstdlib
 valarray cstring
 valarray functional