[libc++] Use availability to rely on key functions for bad_expected_access and bad_function_call (#87390)

This patch uses our availability machinery to allow defining a key
function for bad_function_call and bad_expected_access at all times but
only rely on it when we can. This prevents compilers from complaining
about weak vtables and reduces code bloat and the amount of work done by
the dynamic linker.

rdar://111917845

Author: ldionne

libcxx/include/__availability

@@ -160,6 +160,15 @@
 #  define _LIBCPP_AVAILABILITY_HAS_TZDB 1
 #  define _LIBCPP_AVAILABILITY_TZDB
 
+// These macros determine whether we assume that std::bad_function_call and
+// std::bad_expected_access provide a key function in the dylib. This allows
+// centralizing their vtable and typeinfo instead of having all TUs provide
+// a weak definition that then gets deduplicated.
+#  define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_KEY_FUNCTION 1
+#  define _LIBCPP_AVAILABILITY_BAD_FUNCTION_CALL_KEY_FUNCTION
+#  define _LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION 1
+#  define _LIBCPP_AVAILABILITY_BAD_EXPECTED_ACCESS_KEY_FUNCTION
+
 #elif defined(__APPLE__)
 
 #  define _LIBCPP_AVAILABILITY_HAS_BAD_OPTIONAL_ACCESS                                                                 \
@@ -290,6 +299,13 @@
 #  else
 #    define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 1
 #  endif
+
+#  define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_KEY_FUNCTION 0
+#  define _LIBCPP_AVAILABILITY_BAD_FUNCTION_CALL_KEY_FUNCTION __attribute__((unavailable))
+
+#  define _LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION 0
+#  define _LIBCPP_AVAILABILITY_BAD_EXPECTED_ACCESS_KEY_FUNCTION __attribute__((unavailable))
+
 #else
 
 // ...New vendors can add availability markup here...

libcxx/include/__config

@@ -120,14 +120,11 @@
 #    define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
 #    define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
 #    define _LIBCPP_ABI_FIX_UNORDERED_CONTAINER_SIZE_TYPE
-// Define a key function for `bad_function_call` in the library, to centralize
-// its vtable and typeinfo to libc++ rather than having all other libraries
-// using that class define their own copies.
-#    define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
-// Override the default return value of exception::what() for
-// bad_function_call::what() with a string that is specific to
-// bad_function_call (see http://wg21.link/LWG2233). This is an ABI break
-// because it changes the vtable layout of bad_function_call.
+// Override the default return value of exception::what() for bad_function_call::what()
+// with a string that is specific to bad_function_call (see http://wg21.link/LWG2233).
+// This is an ABI break on platforms that sign and authenticate vtable function pointers
+// because it changes the mangling of the virtual function located in the vtable, which
+// changes how it gets signed.
 #    define _LIBCPP_ABI_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE
 // Enable optimized version of __do_get_(un)signed which avoids redundant copies.
 #    define _LIBCPP_ABI_OPTIMIZED_LOCALE_NUM_GET
@@ -197,19 +194,6 @@
 #    if defined(__FreeBSD__) && __FreeBSD__ < 14
 #      define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 #    endif
-// For XCOFF linkers, we have problems if we see a weak hidden version of a symbol
-// in user code (like you get with -fvisibility-inlines-hidden) and then a strong def
-// in the library, so we need to always rely on the library version.
-#    if defined(_AIX)
-#      define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
-#    endif
-#  endif
-
-#  if defined(_LIBCPP_BUILDING_LIBRARY) || _LIBCPP_ABI_VERSION >= 2
-// Define a key function for `bad_function_call` in the library, to centralize
-// its vtable and typeinfo to libc++ rather than having all other libraries
-// using that class define their own copies.
-#    define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
 #  endif
 
 // We had some bugs where we use [[no_unique_address]] together with construct_at,

libcxx/include/__expected/bad_expected_access.h

@@ -9,6 +9,7 @@
 #ifndef _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H
 #define _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H
 
+#include <__availability>
 #include <__config>
 #include <__exception/exception.h>
 #include <__utility/move.h>
@@ -28,9 +29,11 @@ template <class _Err>
 class bad_expected_access;
 
 _LIBCPP_DIAGNOSTIC_PUSH
+#  if !_LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wweak-vtables")
+#  endif
 template <>
-class bad_expected_access<void> : public exception {
+class _LIBCPP_EXPORTED_FROM_ABI bad_expected_access<void> : public exception {
 protected:
   _LIBCPP_HIDE_FROM_ABI bad_expected_access() noexcept                                      = default;
   _LIBCPP_HIDE_FROM_ABI bad_expected_access(const bad_expected_access&) noexcept            = default;
@@ -40,11 +43,11 @@ class bad_expected_access<void> : public exception {
   _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~bad_expected_access() override                             = default;
 
 public:
-  // The way this has been designed (by using a class template below) means that we'll already
-  // have a profusion of these vtables in TUs, and the dynamic linker will already have a bunch
-  // of work to do. So it is not worth hiding the <void> specialization in the dylib, given that
-  // it adds deployment target restrictions.
+#  if _LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION
+  const char* what() const noexcept override;
+#  else
   _LIBCPP_HIDE_FROM_ABI_VIRTUAL const char* what() const noexcept override { return "bad access to std::expected"; }
+#  endif
 };
 _LIBCPP_DIAGNOSTIC_POP
 

libcxx/include/__functional/function.h

@@ -11,6 +11,7 @@
 #define _LIBCPP___FUNCTIONAL_FUNCTION_H
 
 #include <__assert>
+#include <__availability>
 #include <__config>
 #include <__exception/exception.h>
 #include <__functional/binary_function.h>
@@ -55,7 +56,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 // bad_function_call
 
 _LIBCPP_DIAGNOSTIC_PUSH
+#  if !_LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_KEY_FUNCTION
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wweak-vtables")
+#  endif
 class _LIBCPP_EXPORTED_FROM_ABI bad_function_call : public exception {
 public:
   _LIBCPP_HIDE_FROM_ABI bad_function_call() _NOEXCEPT                                    = default;
@@ -64,7 +67,7 @@ class _LIBCPP_EXPORTED_FROM_ABI bad_function_call : public exception {
 // Note that when a key function is not used, every translation unit that uses
 // bad_function_call will end up containing a weak definition of the vtable and
 // typeinfo.
-#  ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
+#  if _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_KEY_FUNCTION
   ~bad_function_call() _NOEXCEPT override;
 #  else
   _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~bad_function_call() _NOEXCEPT override {}

libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist

@@ -575,6 +575,7 @@
 {'is_defined': True, 'name': '__ZNKSt3__118__time_get_storageIcE15__do_date_orderEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNKSt3__118__time_get_storageIwE15__do_date_orderEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNKSt3__119__shared_weak_count13__get_deleterERKSt9type_info', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNKSt3__119bad_expected_accessIvE4whatEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNKSt3__120__codecvt_utf8_utf16IDiE10do_unshiftER11__mbstate_tPcS4_RS4_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNKSt3__120__codecvt_utf8_utf16IDiE11do_encodingEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNKSt3__120__codecvt_utf8_utf16IDiE13do_max_lengthEv', 'type': 'FUNC'}
@@ -2073,6 +2074,7 @@
 {'is_defined': True, 'name': '__ZTINSt3__117moneypunct_bynameIwLb1EEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__118basic_stringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__119__shared_weak_countE', 'size': 0, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '__ZTINSt3__119bad_expected_accessIvEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__119basic_ostringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTINSt3__120__codecvt_utf8_utf16IDiEE', 'size': 0, 'type': 'OBJECT'}
@@ -2264,6 +2266,7 @@
 {'is_defined': True, 'name': '__ZTSNSt3__117moneypunct_bynameIwLb0EEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__117moneypunct_bynameIwLb1EEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__118basic_stringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '__ZTSNSt3__119bad_expected_accessIvEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__119basic_ostringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTSNSt3__13pmr15memory_resourceE', 'size': 0, 'type': 'OBJECT'}
@@ -2482,6 +2485,7 @@
 {'is_defined': True, 'name': '__ZTVNSt3__117moneypunct_bynameIwLb1EEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__118basic_stringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__119__shared_weak_countE', 'size': 0, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '__ZTVNSt3__119bad_expected_accessIvEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__119basic_ostringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZTVNSt3__120__codecvt_utf8_utf16IDiEE', 'size': 0, 'type': 'OBJECT'}

libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist

@@ -209,6 +209,7 @@
 {'is_defined': True, 'name': '_ZNKSt6__ndk118__time_get_storageIcE15__do_date_orderEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNKSt6__ndk118__time_get_storageIwE15__do_date_orderEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNKSt6__ndk119__shared_weak_count13__get_deleterERKSt9type_info', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNKSt6__ndk119bad_expected_accessIvE4whatEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNKSt6__ndk120__codecvt_utf8_utf16IDiE10do_unshiftER9mbstate_tPcS4_RS4_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNKSt6__ndk120__codecvt_utf8_utf16IDiE11do_encodingEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNKSt6__ndk120__codecvt_utf8_utf16IDiE13do_max_lengthEv', 'type': 'FUNC'}
@@ -1722,6 +1723,7 @@
 {'is_defined': True, 'name': '_ZTINSt6__ndk118__time_get_storageIwEE', 'size': 12, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt6__ndk118basic_stringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 12, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt6__ndk119__shared_weak_countE', 'size': 24, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '_ZTINSt6__ndk119bad_expected_accessIvEE', 'size': 12, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt6__ndk119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 12, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt6__ndk119basic_ostringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 12, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTINSt6__ndk120__codecvt_utf8_utf16IDiEE', 'size': 12, 'type': 'OBJECT'}
@@ -1958,6 +1960,7 @@
 {'is_defined': True, 'name': '_ZTSNSt6__ndk118__time_get_storageIwEE', 'size': 35, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt6__ndk118basic_stringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 72, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt6__ndk119__shared_weak_countE', 'size': 33, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '_ZTSNSt6__ndk119bad_expected_accessIvEE', 'size': 36, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt6__ndk119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 73, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt6__ndk119basic_ostringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 73, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTSNSt6__ndk120__codecvt_utf8_utf16IDiEE', 'size': 38, 'type': 'OBJECT'}
@@ -2188,6 +2191,7 @@
 {'is_defined': True, 'name': '_ZTVNSt6__ndk117moneypunct_bynameIwLb1EEE', 'size': 56, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt6__ndk118basic_stringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 60, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt6__ndk119__shared_weak_countE', 'size': 28, 'type': 'OBJECT'}
+{'is_defined': True, 'name': '_ZTVNSt6__ndk119bad_expected_accessIvEE', 'size': 20, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt6__ndk119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 40, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt6__ndk119basic_ostringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE', 'size': 40, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZTVNSt6__ndk120__codecvt_utf8_utf16IDiEE', 'size': 48, 'type': 'OBJECT'}

libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist

@@ -99,6 +99,7 @@
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__118__time_get_storageIcE15__do_date_orderEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__118__time_get_storageIwE15__do_date_orderEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__119__shared_weak_count13__get_deleterERKSt9type_info', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__119bad_expected_accessIvE4whatEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__120__codecvt_utf8_utf16IDiE10do_unshiftERPcS2_S2_S3_', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__120__codecvt_utf8_utf16IDiE11do_encodingEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNKSt3__120__codecvt_utf8_utf16IDiE13do_max_lengthEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
@@ -910,6 +911,7 @@
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__117__widen_from_utf8ILm32EEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__117bad_function_callE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__119__shared_weak_countE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__119bad_expected_accessIvEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__120__codecvt_utf8_utf16IDiEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__120__codecvt_utf8_utf16IDsEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTINSt3__120__codecvt_utf8_utf16IwEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
@@ -969,6 +971,7 @@
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__117__widen_from_utf8ILm32EEE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__117bad_function_callE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__119__shared_weak_countE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__119bad_expected_accessIvEE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__120__codecvt_utf8_utf16IDiEE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__120__codecvt_utf8_utf16IDsEE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTSNSt3__120__codecvt_utf8_utf16IwEE', 'storage_mapping_class': 'RO', 'type': 'OBJECT'}
@@ -1031,6 +1034,7 @@
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__117__widen_from_utf8ILm32EEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__117bad_function_callE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__119__shared_weak_countE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__119bad_expected_accessIvEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__120__codecvt_utf8_utf16IDiEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__120__codecvt_utf8_utf16IDsEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZTVNSt3__120__codecvt_utf8_utf16IwEE', 'storage_mapping_class': 'RW', 'type': 'OBJECT'}