poppler_gi: fix build on Darwin

pkgs/development/libraries/poppler/default.nix

@@ -10,7 +10,7 @@
 let
   mkFlag = optset: flag: "-DENABLE_${flag}=${if optset then "on" else "off"}";
 in
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (rec {
   name = "poppler-${suffix}-${version}";
   version = "21.02.0"; # beware: updates often break cups-filters build, check texlive and scribusUnstable too!
 
@@ -63,4 +63,17 @@ stdenv.mkDerivation rec {
     platforms = platforms.all;
     maintainers = with maintainers; [ ttuegel ] ++ teams.freedesktop.members;
   };
-}
+} // lib.optionalAttrs stdenv.isDarwin {
+  patches = [
+    # Fix build due to improperly used volatile in poppler-glib.
+    # https://gitlab.freedesktop.org/poppler/poppler/merge_requests/836
+    (fetchpatch {
+      url = "https://gitlab.freedesktop.org/poppler/poppler/commit/47de887d7658cfd68df44b3acf710971054f957b.patch";
+      sha256 = "uvYibBn2fOEqdotxK0Wpf8KhGYZXrpHdmS4jjlRNCj8=";
+    })
+    (fetchpatch {
+      url = "https://gitlab.freedesktop.org/poppler/poppler/commit/bdd110b45a38e8a4f80f522892e4c4a9e432abd5.patch";
+      sha256 = "WDUYXX6v5zk7tusz7DGBP58yFzgEvoBlNSLbfk7+QTc=";
+    })
+  ];
+})