emacs-irony: prebuild irony-server executable

This has melpaBuild compile the irony-server executable automatically.
This means each user of the irony executable doesn’t have to wait for
it to compile on each new use. This depends on this PR to work
correctly:

https://github.com/Sarcasm/irony-mode/pull/537

pkgs/top-level/all-packages.nix

@@ -17600,7 +17600,7 @@ in
       inherit (pythonPackages) elpy;
       inherit
         autoconf automake git libffi libpng pkgconfig poppler rtags w3m zlib
-        substituteAll rustPlatform;
+        substituteAll rustPlatform cmake llvmPackages;
     };
   };
 

pkgs/top-level/emacs-packages.nix

@@ -288,6 +288,45 @@ let
 
   icicles = callPackage ../applications/editors/emacs-modes/icicles { };
 
+  irony = melpaBuild rec {
+    pname = "irony";
+    ename = "irony";
+    version = "20190516";
+    src = fetchFromGitHub {
+      owner = "Sarcasm";
+      repo = "irony-mode";
+      rev = "c3ae899b61124a747ebafc705086345e460ac08e";
+      sha256 = "06ld83vzyklfmrfi6pp893mvlnhacv9if75c9pbipjvy6nwfb63r";
+    };
+    recipe = fetchurl {
+      url = "https://raw.githubusercontent.com/milkypostman/melpa/3cfa28c7314fa57fa9a3aaaadf9ef83f8ae541a9/recipes/irony";
+      sha256 = "1xcxrdrs7imi31nxpszgpaywq4ivni75hrdl4zzrf103xslqpl8a";
+      name = "recipe";
+    };
+    preConfigure = ''
+      cd server
+    '';
+    preBuild = ''
+      make
+    '';
+    postInstall = ''
+      mkdir -p $out
+      mv $out/share/emacs/site-lisp/elpa/*/server/bin $out
+      rm -rf $out/share/emacs/site-lisp/*/server
+    '';
+    preCheck = ''
+      cd source/server
+    '';
+    dontUseCmakeBuildDir = true;
+    doCheck = true;
+    packageRequires = [ emacs ];
+    nativeBuildInputs = [ external.cmake external.llvmPackages.llvm ];
+    meta = {
+      homepage = "https://melpa.org/#/irony";
+      license = lib.licenses.gpl3;
+    };
+  };
+
   redshank = callPackage ../applications/editors/emacs-modes/redshank { };
 
   rtags = melpaBuild rec {