fix: add missing warning for incompatible pointer types in CMake configuration

Author: lum1n0us

build-scripts/warnings.cmake

@@ -16,10 +16,17 @@ else ()
   #
   # -fpermissive causes warnings like "-fpermissive is valid for C++/ObjC++ but not for C"
   #
+  # Reference:
+  #   - gcc-4.8 https://gcc.gnu.org/onlinedocs/gcc-4.8.4/gcc/Warning-Options.html
+  #   - gcc-11.5 https://gcc.gnu.org/onlinedocs/gcc-11.5.0/gcc/Warning-Options.html
   add_compile_options (
-    $<$<COMPILE_LANGUAGE:C>:-Wincompatible-pointer-types>
     $<$<COMPILE_LANGUAGE:C>:-Wimplicit-function-declaration>
   )
+  # https://gcc.gnu.org/gcc-5/changes.html introduces incompatible-pointer-types
+  if (CMAKE_C_COMPILER_ID STREQUAL "GNU" AND CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL "5.1")
+    add_compile_options($<$<COMPILE_LANGUAGE:C>:-Wincompatible-pointer-types>)
+  endif()
+  # options benefit embedded system.
   add_compile_options (
     -Wdouble-promotion
   )