build: suppress clang private field warning

Author: darwin67

CMakeLists.txt

@@ -45,6 +45,7 @@ include(limit_jobs)
 if(DEFINED ENV{NIX_CC})
   add_compile_options(-DFMT_CONSTEVAL=)
   add_compile_options(-Wno-deprecated-literal-operator)
+  add_compile_options(-Wno-unused-private-field)
 endif()
 set(CMAKE_CXX_STANDARD "23" CACHE INTERNAL "")
 set(CMAKE_CXX_EXTENSIONS ON CACHE INTERNAL "")

configure.py

@@ -1676,7 +1676,7 @@ def dynamic_linker_option():
     user_cflags += ' -march=' + args.target
 
 if os.environ.get('NIX_CC'):
-    user_cflags += ' -DFMT_CONSTEVAL= -Wno-deprecated-literal-operator'
+    user_cflags += ' -DFMT_CONSTEVAL= -Wno-deprecated-literal-operator -Wno-unused-private-field'
 
 user_cflags = user_cflags.strip()