Only use -Wno-class-memaccess on gcc 8.0 or higher, as it didn't exist previously.

pcsx2/CMakeLists.txt

@@ -18,13 +18,21 @@ set(CommonFlags
     -Wstrict-aliasing # Allow to track strict aliasing issue.
     -Wno-char-subscripts # only impact svu which is deprecated
     -Wno-missing-braces
-    # Largely turning off because LegacyPluginAPI_Common in Plugins.h spams really badly in gcc 8 due to the memzero initialization.
-    # Should probably be fixed properly, but for now this should work.
-    -Wno-class-memaccess 
     #-Wno-ignored-attributes # don't remember why I put here but it is pure C option, therefore it complains for nothings on cpp files
     -DWX_PRECOMP
 	)
 
+# Largely turning off because LegacyPluginAPI_Common in Plugins.h spams really badly in gcc 8 due to the memzero initialization.
+# Should probably be fixed properly, but for now this should work.
+if(GCC_VERSION VERSION_EQUAL "8.0" OR GCC_VERSION VERSION_GREATER "8.0")
+    set(CommonFlags
+	    ${CommonFlags}
+	    -Wno-class-memaccess
+    )
+endif()
+
+
+
 if ("${PGO}" STREQUAL "generate")
     set(pcsx2FinalFlags -fprofile-generate)
 elseif("${PGO}" STREQUAL "use")

plugins/GSdx/CMakeLists.txt

@@ -14,12 +14,18 @@ set(CommonFlags
     -Wno-unknown-pragmas
     -Wno-parentheses
     -Wunused-variable # __dummy variable need to be investigated
-    # The next two need to be looked at, but spam really badly in gcc 8.
-    # Largely class alignment in GSDevice.h and memcpy in GSVector*.h.
-    -Wno-class-memaccess 
-    -Wno-packed-not-aligned
     )
 
+# The next two need to be looked at, but spam really badly in gcc 8.
+# Largely class alignment in GSDevice.h and memcpy in GSVector*.h.
+if(GCC_VERSION VERSION_EQUAL "8.0" OR GCC_VERSION VERSION_GREATER "8.0")
+    set(CommonFlags
+	    ${CommonFlags}
+        -Wno-class-memaccess
+        -Wno-packed-not-aligned
+    )
+endif()
+
 if(USE_ICC)
     set(CommonFlags "${CommonFlags} -restrict")
 endif()