[libc++] Add std::stacktrace (P0881R7)

libcxx/docs/FeatureTestMacroTable.rst

@@ -396,7 +396,7 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_spanstream``                                   *unimplemented*
     ---------------------------------------------------------- -----------------
-    ``__cpp_lib_stacktrace``                                   *unimplemented*
+    ``__cpp_lib_stacktrace``                                   ``202011L``
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_stdatomic_h``                                  ``202011L``
     ---------------------------------------------------------- -----------------

libcxx/docs/ReleaseNotes/22.rst

@@ -41,6 +41,8 @@ Implemented Papers
 - P2321R2: ``zip`` (`Github <https://github.com/llvm/llvm-project/issues/105169>`__) (The paper is partially
   implemented. ``zip_transform_view`` is implemented in this release)
 - P3168R2: Give ``std::optional`` Range Support (`Github <https://github.com/llvm/llvm-project/issues/105430>`__)
+- P0881R7: A Proposal to add stacktrace library (`Github <https://github.com/llvm/llvm-project/issues/105131>`__)
+- P2301R1: Add a `pmr` alias for `std::stacktrace` (`Github <https://github.com/llvm/llvm-project/issues/105167>`__)
 
 Improvements and New Features
 -----------------------------

libcxx/docs/Status/Cxx23Issues.csv

@@ -189,7 +189,7 @@
 "`LWG3028 <https://wg21.link/LWG3028>`__","Container requirements tables should distinguish ``const`` and non-``const`` variables","2022-11 (Kona)","","",""
 "`LWG3118 <https://wg21.link/LWG3118>`__","``fpos`` equality comparison unspecified","2022-11 (Kona)","","",""
 "`LWG3177 <https://wg21.link/LWG3177>`__","Limit permission to specialize variable templates to program-defined types","2022-11 (Kona)","|Nothing To Do|","",""
-"`LWG3515 <https://wg21.link/LWG3515>`__","§[stacktrace.basic.nonmem]: ``operator<<`` should be less templatized","2022-11 (Kona)","","",""
+"`LWG3515 <https://wg21.link/LWG3515>`__","§[stacktrace.basic.nonmem]: ``operator<<`` should be less templatized","2022-11 (Kona)","|Complete|","",""
 "`LWG3545 <https://wg21.link/LWG3545>`__","``std::pointer_traits`` should be SFINAE-friendly","2022-11 (Kona)","|Complete|","18",""
 "`LWG3569 <https://wg21.link/LWG3569>`__","``join_view`` fails to support ranges of ranges with non-default_initializable iterators","2022-11 (Kona)","","",""
 "`LWG3594 <https://wg21.link/LWG3594>`__","``inout_ptr`` — inconsistent ``release()`` in destructor","2022-11 (Kona)","|Complete|","19",""

libcxx/docs/Status/Cxx23Papers.csv

@@ -1,5 +1,5 @@
 "Paper #","Paper Name","Meeting","Status","First released version","Notes"
-"`P0881R7 <https://wg21.link/P0881R7>`__","A Proposal to add stacktrace library","2020-11 (Virtual)","","",""
+"`P0881R7 <https://wg21.link/P0881R7>`__","A Proposal to add stacktrace library","2020-11 (Virtual)","|Complete|","21",""
 "`P0943R6 <https://wg21.link/P0943R6>`__","Support C atomics in C++","2020-11 (Virtual)","|Complete|","15",""
 "`P1048R1 <https://wg21.link/P1048R1>`__","A proposal for a type trait to detect scoped enumerations","2020-11 (Virtual)","|Complete|","12",""
 "`P1679R3 <https://wg21.link/P1679R3>`__","string contains function","2020-11 (Virtual)","|Complete|","12",""
@@ -32,7 +32,7 @@
 "`P1675R2 <https://wg21.link/P1675R2>`__","``rethrow_exception`` must be allowed to copy","2021-10 (Virtual)","|Nothing To Do|","",""
 "`P2077R3 <https://wg21.link/P2077R3>`__","Heterogeneous erasure overloads for associative containers","2021-10 (Virtual)","","",""
 "`P2251R1 <https://wg21.link/P2251R1>`__","Require ``span`` & ``basic_string_view`` to be Trivially Copyable","2021-10 (Virtual)","|Complete|","14",""
-"`P2301R1 <https://wg21.link/P2301R1>`__","Add a ``pmr`` alias for ``std::stacktrace``","2021-10 (Virtual)","","",""
+"`P2301R1 <https://wg21.link/P2301R1>`__","Add a ``pmr`` alias for ``std::stacktrace``","2021-10 (Virtual)","|Complete|","21",""
 "`P2321R2 <https://wg21.link/P2321R2>`__","``zip``","2021-10 (Virtual)","|In Progress|","",""
 "`P2340R1 <https://wg21.link/P2340R1>`__","Clarifying the status of the 'C headers'","2021-10 (Virtual)","|Nothing To Do|","",""
 "`P2393R1 <https://wg21.link/P2393R1>`__","Cleaning up ``integer``-class types","2021-10 (Virtual)","","",""
@@ -110,7 +110,7 @@
 "`P2713R1 <https://wg21.link/P2713R1>`__","Escaping improvements in ``std::format``","2023-02 (Issaquah)","|Complete|","19",""
 "`P2675R1 <https://wg21.link/P2675R1>`__","``format``'s width estimation is too approximate and not forward compatible","2023-02 (Issaquah)","|Complete|","17",""
 "`P2572R1 <https://wg21.link/P2572R1>`__","``std::format`` fill character allowances","2023-02 (Issaquah)","|Complete|","17",""
-"`P2693R1 <https://wg21.link/P2693R1>`__","Formatting ``thread::id`` and ``stacktrace``","2023-02 (Issaquah)","|Partial|","","The formatter for ``stacktrace`` is not implemented, since ``stacktrace`` is not implemented yet"
+"`P2693R1 <https://wg21.link/P2693R1>`__","Formatting ``thread::id`` and ``stacktrace``","2023-02 (Issaquah)","|Partial|","","The formatter for ``stacktrace`` is not implemented yet"
 "`P2679R2 <https://wg21.link/P2679R2>`__","Fixing ``std::start_lifetime_as`` for arrays","2023-02 (Issaquah)","","",""
 "`P2674R1 <https://wg21.link/P2674R1>`__","A trait for implicit lifetime types","2023-02 (Issaquah)","|Complete|","20",""
 "`P2655R3 <https://wg21.link/P2655R3>`__","``common_reference_t`` of ``reference_wrapper`` Should Be a Reference Type","2023-02 (Issaquah)","|Complete|","21","The paper is implemented as a DR to C++20"

libcxx/include/CMakeLists.txt

@@ -740,6 +740,8 @@ set(files
   __ranges/zip_transform_view.h
   __ranges/zip_view.h
   __split_buffer
+  __stacktrace/basic_stacktrace.h
+  __stacktrace/stacktrace_entry.h
   __std_mbstate_t.h
   __stop_token/atomic_unique_lock.h
   __stop_token/intrusive_list_view.h
@@ -1058,6 +1060,7 @@ set(files
   span
   sstream
   stack
+  stacktrace
   stdatomic.h
   stdbool.h
   stddef.h

libcxx/include/__config

@@ -965,6 +965,33 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_NOINLINE
 #  endif
 
+// Some functions, e.g. std::stacktrace::current, need to avoid being
+// tail-called by (and tail-calling other) functions, for proper enumeration of
+// call-stack frames.
+// clang-format off
+
+// Disables tail-call optimization for "outbound" calls
+// performed in the function annotated with this attribute.
+#  if __has_cpp_attribute(_Clang::__disable_tail_calls__)
+#    define _LIBCPP_NO_TAIL_CALLS_OUT [[_Clang::__disable_tail_calls__]]
+#  elif __has_cpp_attribute(__gnu__::__optimize__)
+#    define _LIBCPP_NO_TAIL_CALLS_OUT [[__gnu__::__optimize__("no-optimize-sibling-calls")]]
+#  else
+#    define _LIBCPP_NO_TAIL_CALLS_OUT
+#  endif
+
+// Disables tail-call optimization for "inbound" calls -- that is,
+// calls from some other function calling the one having this attribute.
+#  if __has_cpp_attribute(_Clang::__not_tail_called__)
+#    define _LIBCPP_NO_TAIL_CALLS_IN [[_Clang::__not_tail_called__]]
+#  else
+#    define _LIBCPP_NO_TAIL_CALLS_IN
+#  endif
+
+// Disable TCO for calls into, and out from, the annotated function.
+#  define _LIBCPP_NO_TAIL_CALLS _LIBCPP_NO_TAIL_CALLS_IN _LIBCPP_NO_TAIL_CALLS_OUT
+// clang-format on
+
 // We often repeat things just for handling wide characters in the library.
 // When wide characters are disabled, it can be useful to have a quick way of
 // disabling it without having to resort to #if-#endif, which has a larger

libcxx/include/__configuration/availability.h

@@ -355,6 +355,10 @@
 #define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE _LIBCPP_INTRODUCED_IN_LLVM_21
 // No attribute, since we've had bad_function_call::what() in the headers before
 
+// This controls the availability of C++23 <stacktrace>.
+#define _LIBCPP_AVAILABILITY_HAS_STACKTRACE _LIBCPP_INTRODUCED_IN_LLVM_21
+#define _LIBCPP_AVAILABILITY_STACKTRACE _LIBCPP_INTRODUCED_IN_LLVM_21_ATTRIBUTE
+
 // Define availability attributes that depend on both
 // _LIBCPP_HAS_EXCEPTIONS and _LIBCPP_HAS_RTTI.
 #if !_LIBCPP_HAS_EXCEPTIONS || !_LIBCPP_HAS_RTTI