libhttpseverywhere: build with latest vala

pkgs/development/libraries/libhttpseverywhere/default.nix

@@ -1,5 +1,5 @@
-{ stdenv, fetchurl, pkgconfig, meson, ninja, makeFontsConf, vala_0_40
-, gnome3, glib, json-glib, libarchive, libsoup, gobject-introspection }:
+{ stdenv, fetchurl, pkgconfig, meson, ninja, makeFontsConf, vala, fetchpatch
+, gnome3, glib, json-glib, libarchive, libsoup, gobject-introspection, valadoc }:
 
 let
   pname = "libhttpseverywhere";
@@ -12,10 +12,17 @@ in stdenv.mkDerivation rec {
     sha256 = "1jmn6i4vsm89q1axlq4ajqkzqmlmjaml9xhw3h9jnal46db6y00w";
   };
 
-  # Broken with newest Vala https://gitlab.gnome.org/GNOME/libhttpseverywhere/issues/1
-  nativeBuildInputs = [ vala_0_40 gobject-introspection meson ninja pkgconfig ];
+  nativeBuildInputs = [ vala gobject-introspection meson ninja pkgconfig ];
   buildInputs = [ glib gnome3.libgee json-glib libsoup libarchive ];
 
+  # Fixes build with vala >=0.42
+  patches = [
+    (fetchpatch {
+      url = "https://gitlab.gnome.org/GNOME/libhttpseverywhere/commit/6da08ef1ade9ea267cecf14dd5cb2c3e6e5e50cb.patch";
+      sha256 = "1nwjlh8iqgjayccwdh0fbpq2g1h8bg1k1g9i324f2bhhvyhmpq8f";
+    })
+  ];
+
   mesonFlags = [ "-Denable_valadoc=true" ];
 
   doCheck = true;