Merge remote-tracking branch 'upstream/gcc-8' into staging-next

Earlier the gcc8 branch was merged instead of the gcc-8 branch (note the dash)...

pkgs/development/ruby-modules/gem-config/default.nix

@@ -242,7 +242,20 @@ in
     nativeBuildInputs = [ pkgconfig ];
     buildInputs = [ openssl ];
     hardeningDisable = [ "format" ];
-    NIX_CFLAGS_COMPILE = [ "-Wno-error=stringop-overflow" "-Wno-error=implicit-fallthrough" ];
+    NIX_CFLAGS_COMPILE = [
+      "-Wno-error=stringop-overflow"
+      "-Wno-error=implicit-fallthrough"
+      "-Wno-error=sizeof-pointer-memaccess"
+      "-Wno-error=cast-function-type"
+      "-Wno-error=class-memaccess"
+      "-Wno-error=ignored-qualifiers"
+      "-Wno-error=tautological-compare"
+    ];
+    dontBuild = false;
+    postPatch = ''
+      substituteInPlace Makefile \
+        --replace '-Wno-invalid-source-encoding' ""
+    '';
   };
 
   hitimes = attrs: {