Add C++23 stacktrace

Author: elsteveogrande

libcxx/CMakeLists.txt

@@ -131,6 +131,11 @@ option(LIBCXX_ENABLE_VENDOR_AVAILABILITY_ANNOTATIONS
    the shared library they shipped should turn this on and see `include/__configuration/availability.h`
    for more details." OFF)
 
+option(LIBCPP_STACKTRACE_ALLOW_TOOLS_AT_RUNTIME
+   "For C++23 <stacktrace>: whether to allow invocation of `addr2line`, `llvm-addr2line` or `atos`
+   at runtime (if it's available in PATH) to resolve call-chain addresses in the stacktrace
+   into source locations, if other methods are not available." ON)
+
 if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
   set(LIBCXX_DEFAULT_TEST_CONFIG "llvm-libc++-shared-gcc.cfg.in")
 elseif(MINGW)
@@ -757,6 +762,7 @@ config_define(${LIBCXX_ENABLE_UNICODE} _LIBCPP_HAS_UNICODE)
 config_define(${LIBCXX_ENABLE_WIDE_CHARACTERS} _LIBCPP_HAS_WIDE_CHARACTERS)
 config_define(${LIBCXX_ENABLE_TIME_ZONE_DATABASE} _LIBCPP_HAS_TIME_ZONE_DATABASE)
 config_define(${LIBCXX_ENABLE_VENDOR_AVAILABILITY_ANNOTATIONS} _LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS)
+config_define(${LIBCPP_STACKTRACE_ALLOW_TOOLS_AT_RUNTIME} _LIBCPP_STACKTRACE_ALLOW_TOOLS_AT_RUNTIME)
 
 # TODO: Remove in LLVM 21. We're leaving an error to make this fail explicitly.
 if (LIBCXX_ENABLE_ASSERTIONS)

libcxx/docs/UserDocumentation.rst

@@ -70,6 +70,7 @@ when ``-fexperimental-library`` is passed:
 
 * The parallel algorithms library (``<execution>`` and the associated algorithms)
 * ``std::chrono::tzdb`` and related time zone functionality
+* ``<stacktrace>``
 * ``<syncstream>``
 
 .. note::

libcxx/docs/VendorDocumentation.rst

@@ -185,6 +185,14 @@ General purpose options
    ship the IANA time zone database. When time zones are not supported,
    time zone support in <chrono> will be disabled.
 
+.. option:: LIBCPP_STACKTRACE_ALLOW_TOOLS_AT_RUNTIME:BOOL
+
+   **Default**: ``OFF``
+
+   For C++23 <stacktrace>: whether to allow invocation of ``addr2line`` or ``llvm-addr2line``
+   at runtime (if it's available in PATH) to resolve call-chain addresses in the stacktrace
+   into source locations, if other methods are not available.
+
 .. option:: LIBCXX_INSTALL_LIBRARY_DIR:PATH
 
   **Default**: ``lib${LIBCXX_LIBDIR_SUFFIX}``

libcxx/include/CMakeLists.txt

@@ -991,10 +991,17 @@ set(files
   experimental/__simd/traits.h
   experimental/__simd/utility.h
   experimental/__simd/vec_ext.h
+  experimental/__stacktrace/basic_stacktrace.h
+  experimental/__stacktrace/detail/alloc.h
+  experimental/__stacktrace/detail/context.h
+  experimental/__stacktrace/detail/entry.h
+  experimental/__stacktrace/detail/to_string.h
+  experimental/__stacktrace/stacktrace_entry.h
   experimental/iterator
   experimental/memory
   experimental/propagate_const
   experimental/simd
+  experimental/stacktrace
   experimental/type_traits
   experimental/utility
   ext/__hash

libcxx/include/__config

@@ -977,6 +977,33 @@ 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/__config_site.in

@@ -33,6 +33,7 @@
 #cmakedefine _LIBCPP_HAS_NO_STD_MODULES
 #cmakedefine01 _LIBCPP_HAS_TIME_ZONE_DATABASE
 #cmakedefine01 _LIBCPP_INSTRUMENTED_WITH_ASAN
+#cmakedefine01 _LIBCPP_STACKTRACE_ALLOW_TOOLS_AT_RUNTIME
 
 // PSTL backends
 #cmakedefine _LIBCPP_PSTL_BACKEND_SERIAL

libcxx/include/__ostream/basic_ostream.h

@@ -570,7 +570,7 @@ _LIBCPP_HIDE_FROM_ABI _Stream&& operator<<(_Stream&& __os, const _Tp& __x) {
 }
 
 template <class _CharT, class _Traits, class _Allocator>
-basic_ostream<_CharT, _Traits>&
+_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, const basic_string<_CharT, _Traits, _Allocator>& __str) {
   return std::__put_character_sequence(__os, __str.data(), __str.size());
 }