rustc: re-add missing file from staging

I'm not sure why it has disappeared.
Also try to fixup with multiple-output changes.

pkgs/development/compilers/rustc/generic.nix

@@ -0,0 +1,168 @@
+{ stdenv, fetchurl, fetchgit, fetchzip, file, python2, tzdata, procps
+, llvmPackages_37, jemalloc, ncurses, binutils
+
+, shortVersion, isRelease
+, srcSha, srcRev ? ""
+, snapshotHashLinux686, snapshotHashLinux64
+, snapshotHashDarwin686, snapshotHashDarwin64
+, snapshotDate, snapshotRev
+, configureFlags ? []
+
+, patches
+}:
+
+assert !stdenv.isFreeBSD;
+
+/* Rust's build process has a few quirks :
+
+- The Rust compiler is written is Rust, so it requires a bootstrap
+  compiler, which is downloaded during the build. To make the build
+  pure, we download it ourself before and put it where it is
+  expected. Once the language is stable (1.0) , we might want to
+  switch it to use nix's packaged rust compiler. This might not be possible
+  as the compiler is highly coupled to the bootstrap.
+
+NOTE : some derivation depend on rust. When updating this, please make
+sure those derivations still compile. (racer, for example).
+
+*/
+
+assert (if isRelease then srcRev == "" else srcRev != "");
+
+let version = if isRelease then
+        "${shortVersion}"
+      else
+        "${shortVersion}-g${builtins.substring 0 7 srcRev}";
+
+    name = "rustc-${version}";
+
+    platform = if stdenv.system == "i686-linux"
+      then "linux-i386"
+      else if stdenv.system == "x86_64-linux"
+      then "linux-x86_64"
+      else if stdenv.system == "i686-darwin"
+      then "macos-i386"
+      else if stdenv.system == "x86_64-darwin"
+      then "macos-x86_64"
+      else abort "no snapshot to bootstrap for this platform (missing platform url suffix)";
+
+    target = if stdenv.system == "i686-linux"
+      then "i686-unknown-linux-gnu"
+      else if stdenv.system == "x86_64-linux"
+      then "x86_64-unknown-linux-gnu"
+      else if stdenv.system == "i686-darwin"
+      then "i686-apple-darwin"
+      else if stdenv.system == "x86_64-darwin"
+      then "x86_64-apple-darwin"
+      else abort "no snapshot to bootstrap for this platform (missing target triple)";
+
+    meta = with stdenv.lib; {
+      homepage = http://www.rust-lang.org/;
+      description = "A safe, concurrent, practical language";
+      maintainers = with maintainers; [ madjar cstrahan wizeman globin havvy wkennington ];
+      license = [ licenses.mit licenses.asl20 ];
+      platforms = platforms.linux;
+    };
+
+    snapshotHash = if stdenv.system == "i686-linux"
+      then snapshotHashLinux686
+      else if stdenv.system == "x86_64-linux"
+      then snapshotHashLinux64
+      else if stdenv.system == "i686-darwin"
+      then snapshotHashDarwin686
+      else if stdenv.system == "x86_64-darwin"
+      then snapshotHashDarwin64
+      else abort "no snapshot for platform ${stdenv.system}";
+    snapshotName = "rust-stage0-${snapshotDate}-${snapshotRev}-${platform}-${snapshotHash}.tar.bz2";
+in
+
+stdenv.mkDerivation {
+  inherit name;
+  inherit version;
+  inherit meta;
+
+  __impureHostDeps = [ "/usr/lib/libedit.3.dylib" ];
+
+  src = if isRelease then
+      fetchzip {
+        url = "http://static.rust-lang.org/dist/rustc-${version}-src.tar.gz";
+        sha256 = srcSha;
+      }
+    else
+      fetchgit {
+        url = https://github.com/rust-lang/rust;
+        rev = srcRev;
+        sha256 = srcSha;
+      };
+
+  # We need rust to build rust. If we don't provide it, configure will try to download it.
+  snapshot = stdenv.mkDerivation {
+    name = "rust-stage0";
+    src = fetchurl {
+      url = "http://static.rust-lang.org/stage0-snapshots/${snapshotName}";
+      sha1 = snapshotHash;
+    };
+    dontStrip = true;
+    installPhase = ''
+      mkdir -p "$out"
+      cp -r bin "$out/bin"
+    '' + stdenv.lib.optionalString stdenv.isLinux ''
+      patchelf --interpreter "${stdenv.glibc.out}/lib/${stdenv.cc.dynamicLinker}" \
+               --set-rpath "${stdenv.cc.cc.lib}/lib/:${stdenv.cc.cc.lib}/lib64/" \
+               "$out/bin/rustc"
+    '';
+  };
+
+  configureFlags = configureFlags
+                ++ [ "--enable-local-rust" "--local-rust-root=$snapshot" "--enable-rpath" ]
+                ++ [ "--llvm-root=${llvmPackages_37.llvm}" ] #"--jemalloc-root=${jemalloc}/lib" ]
+                ++ [ "--default-linker=${stdenv.cc}/bin/cc" "--default-ar=${binutils}/bin/ar" ]
+                ++ stdenv.lib.optional (stdenv.cc.cc ? isClang) "--enable-clang";
+
+  inherit patches;
+
+  postPatch = ''
+    substituteInPlace src/rust-installer/gen-install-script.sh \
+      --replace /bin/echo "$(type -P echo)"
+    substituteInPlace src/rust-installer/gen-installer.sh \
+      --replace /bin/echo "$(type -P echo)"
+
+    # Workaround for NixOS/nixpkgs#8676
+    substituteInPlace mk/rustllvm.mk \
+      --replace "\$\$(subst  /,//," "\$\$(subst /,/,"
+
+    # Fix dynamic linking against llvm
+    sed -i 's/, kind = \\"static\\"//g' src/etc/mklldeps.py
+
+    # Fix the configure script to not require curl as we won't use it
+    sed -i configure \
+      -e '/probe_need CFG_CURLORWGET/d'
+
+    # Fix the use of jemalloc prefixes which our jemalloc doesn't have
+    # TODO: reenable if we can figure out how to get our jemalloc to work
+    #[ -f src/liballoc_jemalloc/lib.rs ] && sed -i 's,je_,,g' src/liballoc_jemalloc/lib.rs
+    #[ -f src/liballoc/heap.rs ] && sed -i 's,je_,,g' src/liballoc/heap.rs # Remove for 1.4.0+
+
+    # Useful debugging parameter
+    #export VERBOSE=1
+  '';
+
+  preConfigure = ''
+    # Needed flags as the upstream configure script has a broken prefix substitution
+    configureFlagsArray+=("--datadir=$out/share")
+    configureFlagsArray+=("--infodir=$out/share/info")
+  '';
+
+  # Procps is needed for one of the test cases
+  nativeBuildInputs = [ file python2 ]
+    ++ stdenv.lib.optionals stdenv.isLinux [ procps ];
+  buildInputs = [ llvmPackages_37.llvm ncurses ];
+
+  enableParallelBuilding = true;
+
+  outputs = [ "out" "doc" ];
+
+  preCheck = "export TZDIR=${tzdata}/share/zoneinfo";
+
+  doCheck = true;
+}