build: IWYU enabled on GCC

CMakeLists.txt

@@ -38,10 +38,6 @@ ensure_entry_point()
 include(ccache)
 enable_ccache(BASE_DIR ${PROJECT_SOURCE_DIR})
 
-# set restrictive compilation warnings
-include(warnings)
-set_warnings()
-
 # enable include-what-you-use
 option(${projectPrefix}DEV_IWYU "Enables include-what-you-use" OFF)
 
@@ -53,6 +49,11 @@ if(${projectPrefix}DEV_IWYU)
         MAX_LINE_LENGTH 120
         NO_COMMENTS
     )
+else()
+    # set restrictive compilation warnings
+    # (some gcc warnings are not recognized by IWYU which is based on clang)
+    include(warnings)
+    set_warnings()
 endif()
 
 # enable_clang_tidy()

cmake/include-what-you-use.cmake

@@ -22,12 +22,6 @@
 
 cmake_minimum_required(VERSION 3.7)
 
-if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-    # run IWYU only for clang compiler
-    # other compilers will generate i.e. unknown compilation flags warnings
-    return()
-endif()
-
 set(IWYU_VERBOSITY_LEVEL 3 CACHE STRING "IWYU verbosity level (the higher the level, the more output)")
 
 macro(_iwyu_args_append arg)