[libc++] Refactor the configuration macros to being always defined (#112094)

This is a follow-up to #89178. This updates the `<__config_site>`
macros.

Author: philnik777

libcxx/CMakeLists.txt

@@ -641,6 +641,8 @@ target_compile_options(cxx-sanitizer-flags INTERFACE ${SANITIZER_FLAGS})
 string(FIND "${LLVM_USE_SANITIZER}" "Address" building_with_asan)
 if (NOT "${building_with_asan}" STREQUAL "-1")
   config_define(ON _LIBCPP_INSTRUMENTED_WITH_ASAN)
+else()
+  config_define(OFF _LIBCPP_INSTRUMENTED_WITH_ASAN)
 endif()
 
 # Link system libraries =======================================================
@@ -734,26 +736,26 @@ endfunction()
 # Configuration file flags =====================================================
 config_define(${LIBCXX_ABI_VERSION} _LIBCPP_ABI_VERSION)
 config_define(${LIBCXX_ABI_NAMESPACE} _LIBCPP_ABI_NAMESPACE)
-config_define_if(LIBCXX_ABI_FORCE_ITANIUM _LIBCPP_ABI_FORCE_ITANIUM)
-config_define_if(LIBCXX_ABI_FORCE_MICROSOFT _LIBCPP_ABI_FORCE_MICROSOFT)
-config_define_if_not(LIBCXX_ENABLE_THREADS _LIBCPP_HAS_NO_THREADS)
-config_define_if_not(LIBCXX_ENABLE_MONOTONIC_CLOCK _LIBCPP_HAS_NO_MONOTONIC_CLOCK)
-config_define_if_not(LIBCXX_HAS_TERMINAL_AVAILABLE _LIBCPP_HAS_NO_TERMINAL)
+config_define(${LIBCXX_ABI_FORCE_ITANIUM} _LIBCPP_ABI_FORCE_ITANIUM)
+config_define(${LIBCXX_ABI_FORCE_MICROSOFT} _LIBCPP_ABI_FORCE_MICROSOFT)
+config_define(${LIBCXX_ENABLE_THREADS} _LIBCPP_HAS_THREADS)
+config_define(${LIBCXX_ENABLE_MONOTONIC_CLOCK} _LIBCPP_HAS_MONOTONIC_CLOCK)
+config_define(${LIBCXX_HAS_TERMINAL_AVAILABLE} _LIBCPP_HAS_TERMINAL)
 if (NOT LIBCXX_TYPEINFO_COMPARISON_IMPLEMENTATION STREQUAL "default")
   config_define("${LIBCXX_TYPEINFO_COMPARISON_IMPLEMENTATION}" _LIBCPP_TYPEINFO_COMPARISON_IMPLEMENTATION)
 endif()
-config_define_if(LIBCXX_HAS_PTHREAD_API _LIBCPP_HAS_THREAD_API_PTHREAD)
-config_define_if(LIBCXX_HAS_EXTERNAL_THREAD_API _LIBCPP_HAS_THREAD_API_EXTERNAL)
-config_define_if(LIBCXX_HAS_WIN32_THREAD_API _LIBCPP_HAS_THREAD_API_WIN32)
-config_define_if(LIBCXX_HAS_MUSL_LIBC _LIBCPP_HAS_MUSL_LIBC)
+config_define(${LIBCXX_HAS_PTHREAD_API} _LIBCPP_HAS_THREAD_API_PTHREAD)
+config_define(${LIBCXX_HAS_EXTERNAL_THREAD_API} _LIBCPP_HAS_THREAD_API_EXTERNAL)
+config_define(${LIBCXX_HAS_WIN32_THREAD_API} _LIBCPP_HAS_THREAD_API_WIN32)
+config_define(${LIBCXX_HAS_MUSL_LIBC} _LIBCPP_HAS_MUSL_LIBC)
 config_define_if(LIBCXX_NO_VCRUNTIME _LIBCPP_NO_VCRUNTIME)
-config_define_if_not(LIBCXX_ENABLE_FILESYSTEM _LIBCPP_HAS_NO_FILESYSTEM)
-config_define_if_not(LIBCXX_ENABLE_RANDOM_DEVICE _LIBCPP_HAS_NO_RANDOM_DEVICE)
-config_define_if_not(LIBCXX_ENABLE_LOCALIZATION _LIBCPP_HAS_NO_LOCALIZATION)
-config_define_if_not(LIBCXX_ENABLE_UNICODE _LIBCPP_HAS_NO_UNICODE)
-config_define_if_not(LIBCXX_ENABLE_WIDE_CHARACTERS _LIBCPP_HAS_NO_WIDE_CHARACTERS)
-config_define_if_not(LIBCXX_ENABLE_TIME_ZONE_DATABASE _LIBCPP_HAS_NO_TIME_ZONE_DATABASE)
-config_define_if_not(LIBCXX_ENABLE_VENDOR_AVAILABILITY_ANNOTATIONS _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
+config_define(${LIBCXX_ENABLE_FILESYSTEM} _LIBCPP_HAS_FILESYSTEM)
+config_define(${LIBCXX_ENABLE_RANDOM_DEVICE} _LIBCPP_HAS_RANDOM_DEVICE)
+config_define(${LIBCXX_ENABLE_LOCALIZATION} _LIBCPP_HAS_LOCALIZATION)
+config_define(${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)
 
 # TODO: Remove in LLVM 21. We're leaving an error to make this fail explicitly.
 if (LIBCXX_ENABLE_ASSERTIONS)

libcxx/docs/DesignDocs/ThreadingSupportAPI.rst

@@ -45,9 +45,9 @@ API but leaves out the implementation.
 Threading Configuration Macros
 ==============================
 
-**_LIBCPP_HAS_NO_THREADS**
-  This macro is defined when libc++ is built without threading support. It
-  should not be manually defined by the user.
+**_LIBCPP_HAS_THREADS**
+  This macro is set to 1 when libc++ is built with threading support. Otherwise
+  it is set to 0. It should not be manually defined by the user.
 
 **_LIBCPP_HAS_THREAD_API_EXTERNAL**
   This macro is defined when libc++ should use the ``<__external_threading>``