cpp: add kconfig option STD_CPP23 for STD_CPP

to be able to choose c++23 dialect
deprecates c++2b, but we should keep the option c++2b for legacy

Signed-off-by: Adrian Bieri <adrian.bieri@loepfe.com>

Author: bia-bonobo

CMakeLists.txt

@@ -302,6 +302,9 @@ if(CONFIG_CPP)
   elseif(CONFIG_STD_CPP2B)
     set(STD_CPP_DIALECT_FLAGS $<TARGET_PROPERTY:compiler-cpp,dialect_cpp2b>)
     list(APPEND CMAKE_CXX_COMPILE_FEATURES ${compile_features_cpp20})
+  elseif(CONFIG_STD_CPP23)
+    set(STD_CPP_DIALECT_FLAGS $<TARGET_PROPERTY:compiler-cpp,dialect_cpp23>)
+    list(APPEND CMAKE_CXX_COMPILE_FEATURES ${compile_features_cpp23})
   else()
     message(FATAL_ERROR
       "Unreachable code. Expected C++ standard to have been chosen. See Kconfig.zephyr.")

cmake/compiler/arcmwdt/compiler_flags.cmake

@@ -127,10 +127,11 @@ set_property(TARGET compiler-cpp PROPERTY dialect_cpp11 "-std=c++11")
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp14 "-std=c++14")
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp17 "-std=c++17")
 
-#no support of C++2a, C++20, C++2b
+# no support of C++2a, C++20, C++2b, C++23
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2a "")
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp20 "")
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2b "")
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp23 "")
 
 # Flag for disabling strict aliasing rule in C and C++
 set_compiler_property(PROPERTY no_strict_aliasing -fno-strict-aliasing)

cmake/compiler/compiler_features.cmake

@@ -24,3 +24,4 @@ set(compile_features_cpp11 cxx_std_11 ${compile_features_cpp98})
 set(compile_features_cpp14 cxx_std_14 ${compile_features_cpp11})
 set(compile_features_cpp17 cxx_std_17 ${compile_features_cpp14})
 set(compile_features_cpp20 cxx_std_20 ${compile_features_cpp17})
+set(compile_features_cpp23 cxx_std_23 ${compile_features_cpp20})

cmake/compiler/compiler_flags_template.cmake

@@ -68,6 +68,7 @@ set_property(TARGET compiler-cpp PROPERTY dialect_cpp17)
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2a)
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp20)
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2b)
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp23)
 
 # Flag for disabling strict aliasing rule in C and C++
 set_compiler_property(PROPERTY no_strict_aliasing)

cmake/compiler/gcc/compiler_flags.cmake

@@ -146,6 +146,8 @@ set_property(TARGET compiler-cpp PROPERTY dialect_cpp20 "-std=c++20"
   "-Wno-register" "-Wno-volatile")
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2b "-std=c++2b"
   "-Wno-register" "-Wno-volatile")
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp23 "-std=c++23"
+  "-Wno-register" "-Wno-volatile")
 
 # Flag for disabling strict aliasing rule in C and C++
 set_compiler_property(PROPERTY no_strict_aliasing -fno-strict-aliasing)

cmake/compiler/iar/compiler_flags.cmake

@@ -120,6 +120,7 @@ set_property(TARGET compiler-cpp PROPERTY dialect_cpp17 --libc++)
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2a --libc++)
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp20 --libc++)
 set_property(TARGET compiler-cpp PROPERTY dialect_cpp2b --libc++)
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp23 --libc++)
 
 # Flag for disabling strict aliasing rule in C and C++
 set_compiler_property(PROPERTY no_strict_aliasing)

lib/cpp/Kconfig

@@ -18,7 +18,8 @@ config STD_CPP_VERSION
 	default 201103 if STD_CPP11
 	default 201402 if STD_CPP14
 	default 201703 if STD_CPP17
-	default 202002 if STD_CPP20 || STD_CPP2A || STD_CPP2B
+	default 202002 if STD_CPP20 || STD_CPP2A
+	default 202302 if STD_CPP23 || STD_CPP2B
 	help
 	  The version number of C++ standard being used (NOTE: this uses the
 	  full year and month, and is the same as the __cplusplus macro defined
@@ -75,6 +76,11 @@ config STD_CPP2B
 	help
 	  Next revision of the C++ standard, which is expected to be published in 2023.
 
+config STD_CPP23
+	bool "C++ 23"
+	help
+	  2023 C++ standard, previously known as C++2B.
+
 endchoice
 
 config REQUIRES_FULL_LIBCPP

tests/lib/cpp/cxx/testcase.yaml

@@ -70,8 +70,11 @@ tests:
       - CONFIG_STD_CPP20=y
   cpp.main.cpp2B:
     arch_exclude: posix
-    toolchain_exclude:
-      - xt-clang
     build_only: true
     extra_configs:
       - CONFIG_STD_CPP2B=y
+  cpp.main.cpp23:
+    arch_exclude: posix
+    build_only: true
+    extra_configs:
+      - CONFIG_STD_CPP23=y