add the correct flags to the build for char8_t

Author: phlptp

units/CMakeLists.txt

@@ -223,11 +223,20 @@ endif()
 
 if(UNITS_BUILD_CXX_MODULE)
     add_library(module)
-    target_link_libraries(module PUBLIC ${UNITS_LC_PROJECT_NAME}::units)
+    target_link_libraries(
+        module PUBLIC ${UNITS_LC_PROJECT_NAME}::units PRIVATE compile_flags_target
+    )
     target_compile_features(module PUBLIC cxx_std_20)
     set_target_properties(
         module PROPERTIES CXX_STANDARD ${CMAKE_CXX_STANDARD} CXX_STANDARD_REQUIRED ON
     )
+    if(CMAKE_CXX_STANDARD GREATER 19)
+        if(MSVC)
+            target_compile_options(module PUBLIC /Zc:char8_t-)
+        else()
+            target_compile_options(module PUBLIC -fno-char8_t)
+        endif()
+    endif()
     target_sources(
         module PUBLIC FILE_SET cxx_modules TYPE CXX_MODULES FILES ${units_module_files}
     )