difftastic: use existing tree-sitter grammars when possible

pkgs/tools/text/difftastic/default.nix

@@ -1,4 +1,4 @@
-{ lib, fetchFromGitHub, rustPlatform }:
+{ lib, fetchFromGitHub, rustPlatform, tree-sitter }:
 
 rustPlatform.buildRustPackage rec {
   pname = "difftastic";
@@ -13,11 +13,22 @@ rustPlatform.buildRustPackage rec {
 
   cargoSha256 = "sha256-2xGwS4wjLQ7zmfZ2gMdlUAkjPDF6SmUaiX2j1KYy0vo=";
 
+  postPatch = ''
+    pushd vendor
+    for grammar in */; do
+      if [ -d "${tree-sitter.grammars}/$grammar" ]; then
+        rm -r "$grammar"
+        ln -s "${tree-sitter.grammars}/$grammar"
+      fi
+    done
+    popd
+  '';
+
   meta = with lib; {
     description = "A syntax-aware diff";
     homepage = "https://github.com/Wilfred/difftastic";
     changelog = "https://github.com/Wilfred/difftastic/raw/${version}/CHANGELOG.md";
     license = licenses.mit;
-    maintainers = with maintainers; [ ethancedwards8 ];
+    maintainers = with maintainers; [ ethancedwards8 figsoda ];
   };
 }