emscriptenfastcomp: build using cmake and use cc-wrapper

pkgs/development/compilers/emscripten-fastcomp/default.nix

@@ -1,13 +1,13 @@
-{ stdenv, fetchFromGitHub, python }:
+{ stdenv, fetchFromGitHub, cmake, python, ... }:
 
 let
   rev = "1.36.4";
+  gcc = if stdenv.cc.isGNU then stdenv.cc.cc else stdenv.cc.cc.gcc;
 in
-
 stdenv.mkDerivation rec {
   name = "emscripten-fastcomp-${rev}";
 
-  srcFC = fetchFromGitHub {
+  src = fetchFromGitHub {
     owner = "kripken";
     repo = "emscripten-fastcomp";
     sha256 = "0838rl0n9hyq5dd0gmj5rvigbmk5mhrhzyjk0zd8mjs2mk8z510l";
@@ -21,24 +21,32 @@ stdenv.mkDerivation rec {
     inherit rev;
   };
 
-  buildInputs = [ python ];
-  buildCommand = ''
-    cp -as ${srcFC} $TMPDIR/src
-    chmod +w $TMPDIR/src/tools
-    cp -as ${srcFL} $TMPDIR/src/tools/clang
-
-    chmod +w $TMPDIR/src
-    mkdir $TMPDIR/src/build
-    cd $TMPDIR/src/build
-
-    ../configure --enable-optimized --disable-assertions --enable-targets=host,js
-    make
-    cp -a Release/bin $out
+  nativeBuildInputs = [ cmake python ];
+  preConfigure = ''
+    cp -Lr ${srcFL} tools/clang
+    chmod +w -R tools/clang
   '';
+  cmakeFlags = [
+    "-DCMAKE_BUILD_TYPE=Release"
+    "-DLLVM_TARGETS_TO_BUILD='X86;JSBackend'"
+    "-DLLVM_INCLUDE_EXAMPLES=OFF"
+    "-DLLVM_INCLUDE_TESTS=OFF"
+    # "-DCLANG_INCLUDE_EXAMPLES=OFF"
+    "-DCLANG_INCLUDE_TESTS=OFF"
+  ] ++ (stdenv.lib.optional stdenv.isLinux
+    # necessary for clang to find crtend.o
+    "-DGCC_INSTALL_PREFIX=${gcc}"
+  );
+  enableParallelBuilding = true;
+
+  passthru = {
+    isClang = true;
+    inherit gcc;
+  };
 
   meta = with stdenv.lib; {
     homepage = https://github.com/kripken/emscripten-fastcomp;
-    description = "Emscripten llvm";
+    description = "Emscripten LLVM";
     platforms = platforms.all;
     maintainers = with maintainers; [ qknight matthewbauer ];
     license = stdenv.lib.licenses.ncsa;