[CMake][NFC] Disable mismatched-new-delete warning in GCC (#19)

The warning triggers for the overloads for operator new/delete in
BumpAllocator, because the BumpAllocator class is templated with the
SlabSize. GCC does select the correct overload of operator new/delete,
but produces a warning. Since we build with -Wall -Werror this results
in a compile error. We are in the process of reporting this to GCC, but
for now let's disable the warning.

Author: marcauberer

CMakeLists.txt

@@ -52,6 +52,12 @@ else ()
         # We often add unreachable() to default cases
         add_compile_options(-Wno-covered-switch-default)
         add_compile_options(-Wsign-compare)
+    elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+        # Operator new/delete overloads with templated arguments trigger this. This is likely a bug in GCC.
+        # GCC does the right thing but emits a warning.
+        # Bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123513
+        # Since we compile with -Wall -Werror we need to disable this warning for now.
+        add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wno-mismatched-new-delete>)
     endif ()
 
     check_linker_flag(CXX "LINKER:--gc-sections" HAVE_GC_SECTIONS)