We generally disable PCH in Gentoo because of how buggy it is.
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -400,7 +400,7 @@ endif()
 
 # Add frequently included header files for pre-compiling.
 # target_precompile_headers is supported by CMake 3.16.0 or newer.
-if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.16.0")
+if(FALSE)
   if(MOLD_IS_SOLD)
     target_precompile_headers(mold PRIVATE
       "$<$<COMPILE_LANGUAGE:CXX>:${CMAKE_SOURCE_DIR}/elf/mold.h>"