buildRustCrate: extracted builder scripts into dedicated files

The build expression got quiet large over time and to make it a bit
easier to grasp the different scripts involved in the build are now
separated from the nix file.

4 files changed, 343 insertions, 494 deletions

diff --git a/pkgs/build-support/rust/build-rust-crate.nix b/pkgs/build-support/rust/build-rust-crate.nix
deleted file mode 100644
index cfdf38958a8..00000000000
--- a/pkgs/build-support/rust/build-rust-crate.nix
+++ /dev/null
@@ -1,494 +0,0 @@
-# Code for buildRustCrate, a Nix function that builds Rust code, just
-# like Cargo, but using Nix instead.
-#
-# This can be useful for deploying packages with NixOps, and to share
-# binary dependencies between projects.
-
-{ lib, stdenv, defaultCrateOverrides, fetchCrate, ncurses, rustc  }:
-
-let makeDeps = dependencies:
-      (lib.concatMapStringsSep " " (dep:
-        let extern = lib.strings.replaceStrings ["-"] ["_"] dep.libName; in
-        (if dep.crateType == "lib" then
-           " --extern ${extern}=${dep.out}/lib/lib${extern}-${dep.metadata}.rlib"
-         else
-           " --extern ${extern}=${dep.out}/lib/lib${extern}-${dep.metadata}${stdenv.hostPlatform.extensions.sharedLibrary}")
-      ) dependencies);
-
-    # This doesn't appear to be officially documented anywhere yet.
-    # See https://github.com/rust-lang-nursery/rust-forge/issues/101.
-    target_os = if stdenv.hostPlatform.isDarwin
-      then "macos"
-      else stdenv.hostPlatform.parsed.kernel.name;
-
-    echo_build_heading = colors: ''
-      echo_build_heading() {
-       start=""
-       end=""
-       if [[ "${colors}" == "always" ]]; then
-         start="$(printf '\033[0;1;32m')" #set bold, and set green.
-         end="$(printf '\033[0m')" #returns to "normal"
-       fi
-       if (( $# == 1 )); then
-         echo "$start""Building $1""$end"
-       else
-         echo "$start""Building $1 ($2)""$end"
-       fi
-      }
-    '';
-    noisily = colors: verbose: ''
-      noisily() {
-        start=""
-        end=""
-        if [[ "${colors}" == "always" ]]; then
-          start="$(printf '\033[0;1;32m')" #set bold, and set green.
-          end="$(printf '\033[0m')" #returns to "normal"
-        fi
-	${lib.optionalString verbose ''
-            echo -n "$start"Running "$end"
-            echo $@
-	''}
-	$@
-      }
-    '';
-
-    configureCrate =
-      { crateName, crateVersion, crateAuthors, build, libName, crateFeatures, colors, libPath, release, buildDependencies, completeDeps, completeBuildDeps, verbose, workspace_member, extraLinkFlags }:
-      let version_ = lib.splitString "-" crateVersion;
-          versionPre = if lib.tail version_ == [] then "" else builtins.elemAt version_ 1;
-          version = lib.splitString "." (lib.head version_);
-          rustcOpts = (if release then "-C opt-level=3" else "-C debuginfo=2");
-          buildDeps = makeDeps buildDependencies;
-          authors = lib.concatStringsSep ":" crateAuthors;
-          optLevel = if release then 3 else 0;
-          completeDepsDir = lib.concatStringsSep " " completeDeps;
-          completeBuildDepsDir = lib.concatStringsSep " " completeBuildDeps;
-      in ''
-      cd ${workspace_member}
-      runHook preConfigure
-      ${echo_build_heading colors}
-      ${noisily colors verbose}
-      symlink_dependency() {
-        # $1 is the nix-store path of a dependency
-        # $2 is the target path
-        i=$1
-        ln -s -f $i/lib/*.rlib $2 #*/
-        ln -s -f $i/lib/*.so $i/lib/*.dylib $2 #*/
-        if [ -e "$i/lib/link" ]; then
-            cat $i/lib/link >> target/link
-            cat $i/lib/link >> target/link.final
-        fi
-        if [ -e $i/env ]; then
-            source $i/env
-        fi
-      }
-
-      mkdir -p target/{deps,lib,build,buildDeps}
-      chmod uga+w target -R
-      echo ${extraLinkFlags} > target/link
-      echo ${extraLinkFlags} > target/link.final
-      for i in ${completeDepsDir}; do
-        symlink_dependency $i target/deps
-      done
-      for i in ${completeBuildDepsDir}; do
-         symlink_dependency $i target/buildDeps
-      done
-      if [[ -e target/link ]]; then
-        sort -u target/link > target/link.sorted
-        mv target/link.sorted target/link
-        sort -u target/link.final > target/link.final.sorted
-        mv target/link.final.sorted target/link.final
-        tr '\n' ' ' < target/link > target/link_
-      fi
-      EXTRA_BUILD=""
-      BUILD_OUT_DIR=""
-      export CARGO_PKG_NAME=${crateName}
-      export CARGO_PKG_VERSION=${crateVersion}
-      export CARGO_PKG_AUTHORS="${authors}"
-
-      export CARGO_CFG_TARGET_ARCH=${stdenv.hostPlatform.parsed.cpu.name}
-      export CARGO_CFG_TARGET_OS=${target_os}
-      export CARGO_CFG_TARGET_FAMILY="unix"
-      export CARGO_CFG_UNIX=1
-      export CARGO_CFG_TARGET_ENV="gnu"
-      export CARGO_CFG_TARGET_ENDIAN=${if stdenv.hostPlatform.parsed.cpu.significantByte.name == "littleEndian" then "little" else "big"}
-      export CARGO_CFG_TARGET_POINTER_WIDTH=${toString stdenv.hostPlatform.parsed.cpu.bits}
-      export CARGO_CFG_TARGET_VENDOR=${stdenv.hostPlatform.parsed.vendor.name}
-
-      export CARGO_MANIFEST_DIR="."
-      export DEBUG="${toString (!release)}"
-      export OPT_LEVEL="${toString optLevel}"
-      export TARGET="${stdenv.hostPlatform.config}"
-      export HOST="${stdenv.hostPlatform.config}"
-      export PROFILE=${if release then "release" else "debug"}
-      export OUT_DIR=$(pwd)/target/build/${crateName}.out
-      export CARGO_PKG_VERSION_MAJOR=${builtins.elemAt version 0}
-      export CARGO_PKG_VERSION_MINOR=${builtins.elemAt version 1}
-      export CARGO_PKG_VERSION_PATCH=${builtins.elemAt version 2}
-      if [[ -n "${versionPre}" ]]; then
-        export CARGO_PKG_VERSION_PRE="${versionPre}"
-      fi
-
-      BUILD=""
-      if [[ ! -z "${build}" ]] ; then
-         BUILD=${build}
-      elif [[ -e "build.rs" ]]; then
-         BUILD="build.rs"
-      fi
-      if [[ ! -z "$BUILD" ]] ; then
-         echo_build_heading "$BUILD" ${libName}
-         mkdir -p target/build/${crateName}
-         EXTRA_BUILD_FLAGS=""
-         if [ -e target/link_ ]; then
-           EXTRA_BUILD_FLAGS=$(cat target/link_)
-         fi
-         if [ -e target/link.build ]; then
-           EXTRA_BUILD_FLAGS="$EXTRA_BUILD_FLAGS $(cat target/link.build)"
-         fi
-         noisily rustc --crate-name build_script_build $BUILD --crate-type bin ${rustcOpts} \
-           ${crateFeatures} --out-dir target/build/${crateName} --emit=dep-info,link \
-           -L dependency=target/buildDeps ${buildDeps} --cap-lints allow $EXTRA_BUILD_FLAGS --color ${colors}
-
-         mkdir -p target/build/${crateName}.out
-         export RUST_BACKTRACE=1
-         BUILD_OUT_DIR="-L $OUT_DIR"
-         mkdir -p $OUT_DIR
-         target/build/${crateName}/build_script_build > target/build/${crateName}.opt
-         set +e
-         EXTRA_BUILD=$(sed -n "s/^cargo:rustc-flags=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
-         EXTRA_FEATURES=$(sed -n "s/^cargo:rustc-cfg=\(.*\)/--cfg \1/p" target/build/${crateName}.opt | tr '\n' ' ')
-         EXTRA_LINK=$(sed -n "s/^cargo:rustc-link-lib=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
-         EXTRA_LINK_SEARCH=$(sed -n "s/^cargo:rustc-link-search=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
-
-         for env in $(sed -n "s/^cargo:rustc-env=\(.*\)/\1/p" target/build/${crateName}.opt); do
-           export $env
-         done
-
-         CRATENAME=$(echo ${crateName} | sed -e "s/\(.*\)-sys$/\U\1/")
-         grep -P "^cargo:(?!(rustc-|warning=|rerun-if-changed=|rerun-if-env-changed))" target/build/${crateName}.opt \
-           | sed -e "s/cargo:\([^=]*\)=\(.*\)/export DEP_$(echo $CRATENAME)_\U\1\E=\2/" > target/env
-
-         set -e
-         if [[ -n "$(ls target/build/${crateName}.out)" ]]; then
-
-            if [[ -e "${libPath}" ]]; then
-               cp -r target/build/${crateName}.out/* $(dirname ${libPath}) #*/
-            else
-               cp -r target/build/${crateName}.out/* src #*/
-            fi
-         fi
-      fi
-      runHook postConfigure
-    '';
-
-    buildCrate = { crateName,
-                   dependencies,
-                   crateFeatures, libName, release, libPath,
-                   crateType, metadata, crateBin, finalBins,
-                   extraRustcOpts, verbose, colors }:
-
-      let deps = makeDeps dependencies;
-          rustcOpts =
-            lib.lists.foldl' (opts: opt: opts + " " + opt)
-              (if release then "-C opt-level=3" else "-C debuginfo=2")
-              (["-C codegen-units=1"] ++ extraRustcOpts);
-          rustcMeta = "-C metadata=${metadata} -C extra-filename=-${metadata}";
-      in ''
-      runHook preBuild
-      norm=""
-      bold=""
-      green=""
-      boldgreen=""
-      if [[ "${colors}" == "always" ]]; then
-        norm="$(printf '\033[0m')" #returns to "normal"
-        bold="$(printf '\033[0;1m')" #set bold
-        green="$(printf '\033[0;32m')" #set green
-        boldgreen="$(printf '\033[0;1;32m')" #set bold, and set green.
-      fi
-      ${echo_build_heading colors}
-      ${noisily colors verbose}
-
-      build_lib() {
-         lib_src=$1
-         echo_build_heading $lib_src ${libName}
-
-         noisily rustc --crate-name $CRATE_NAME $lib_src --crate-type ${crateType} \
-           ${rustcOpts} ${rustcMeta} ${crateFeatures} --out-dir target/lib \
-           --emit=dep-info,link -L dependency=target/deps ${deps} --cap-lints allow \
-           $BUILD_OUT_DIR $EXTRA_BUILD $EXTRA_FEATURES --color ${colors}
-
-         EXTRA_LIB=" --extern $CRATE_NAME=target/lib/lib$CRATE_NAME-${metadata}.rlib"
-         if [ -e target/deps/lib$CRATE_NAME-${metadata}${stdenv.hostPlatform.extensions.sharedLibrary} ]; then
-            EXTRA_LIB="$EXTRA_LIB --extern $CRATE_NAME=target/lib/lib$CRATE_NAME-${metadata}${stdenv.hostPlatform.extensions.sharedLibrary}"
-         fi
-      }
-
-      build_bin() {
-        crate_name=$1
-        crate_name_=$(echo $crate_name | sed -e "s/-/_/g")
-        main_file=""
-        if [[ ! -z $2 ]]; then
-          main_file=$2
-        fi
-        echo_build_heading $@
-        noisily rustc --crate-name $crate_name_ $main_file --crate-type bin ${rustcOpts}\
-          ${crateFeatures} --out-dir target/bin --emit=dep-info,link -L dependency=target/deps \
-          $LINK ${deps}$EXTRA_LIB --cap-lints allow \
-          $BUILD_OUT_DIR $EXTRA_BUILD $EXTRA_FEATURES --color ${colors}
-        if [ "$crate_name_" != "$crate_name" ]; then
-          mv target/bin/$crate_name_ target/bin/$crate_name
-        fi
-      }
-
-
-      EXTRA_LIB=""
-      CRATE_NAME=$(echo ${libName} | sed -e "s/-/_/g")
-
-      if [[ -e target/link_ ]]; then
-        EXTRA_BUILD="$(cat target/link_) $EXTRA_BUILD"
-      fi
-
-      if [[ -e "${libPath}" ]]; then
-         build_lib ${libPath}
-      elif [[ -e src/lib.rs ]]; then
-         build_lib src/lib.rs
-      elif [[ -e src/${libName}.rs ]]; then
-         build_lib src/${libName}.rs
-      fi
-
-      echo "$EXTRA_LINK_SEARCH" | while read i; do
-         if [[ ! -z "$i" ]]; then
-           for lib in $i; do
-             echo "-L $lib" >> target/link
-             L=$(echo $lib | sed -e "s#$(pwd)/target/build#$out/lib#")
-             echo "-L $L" >> target/link.final
-           done
-         fi
-      done
-      echo "$EXTRA_LINK" | while read i; do
-         if [[ ! -z "$i" ]]; then
-           for lib in $i; do
-             echo "-l $lib" >> target/link
-             echo "-l $lib" >> target/link.final
-           done
-         fi
-      done
-
-      if [[ -e target/link ]]; then
-         sort -u target/link.final > target/link.final.sorted
-         mv target/link.final.sorted target/link.final
-         sort -u target/link > target/link.sorted
-         mv target/link.sorted target/link
-
-         tr '\n' ' ' < target/link > target/link_
-         LINK=$(cat target/link_)
-      fi
-
-      mkdir -p target/bin
-      printf "%s\n" "${crateBin}" | head -n1 | tr -s ',' '\n' | while read -r BIN_NAME BIN_PATH; do
-        # filter empty entries / empty "lines"
-        if [[ -z "$BIN_NAME" ]]; then
-             continue
-        fi
-
-        if [[ -z "$BIN_PATH" ]]; then
-          # heuristic to "guess" the correct source file as found in cargo:
-          # https://github.com/rust-lang/cargo/blob/90fc9f620190d5fa3c80b0c8c65a1e1361e6b8ae/src/cargo/util/toml/targets.rs#L308-L325
-
-          # the first two cases are the "new" default IIRC
-          BIN_NAME_=$(echo $BIN_NAME | sed -e 's/-/_/g')
-          FILES="src/bin/$BIN_NAME_.rs src/bin/$BIN_NAME_/main.rs src/bin/main.rs src/main.rs"
-
-          if ! [ -e "${libPath}" -o -e src/lib.rs -o -e "src/${libName}.rs" ]; then
-            # if this is not a library the following path is also valid
-            FILES="src/$BIN_NAME_.rs $FILES"
-          fi
-
-          echo $FILES
-          for file in $FILES;
-          do
-            echo "checking file $file"
-            # first file that exists wins
-            if [[ -e "$file" ]]; then
-                    BIN_PATH="$file"
-                    break
-            fi
-          done
-
-          if [[ -z "$BIN_PATH" ]]; then
-            echo "failed to find file for binary target: $BIN_NAME" >&2
-            exit 1
-          fi
-        fi
-        build_bin $BIN_NAME $BIN_PATH
-      done
-
-
-      ${lib.optionalString (crateBin == "") ''
-        if [[ -e src/main.rs ]]; then
-          build_bin ${crateName} src/main.rs
-        fi
-        for i in src/bin/*.rs; do #*/
-          build_bin "$(basename $i .rs)" "$i"
-        done
-      ''}
-      # Remove object files to avoid "wrong ELF type"
-      find target -type f -name "*.o" -print0 | xargs -0 rm -f
-    '' + finalBins + ''
-      runHook postBuild
-    '';
-
-    installCrate = crateName: metadata: ''
-      runHook preInstall
-      mkdir -p $out
-      if [[ -s target/env ]]; then
-        cp target/env $out/env
-      fi
-      if [[ -s target/link.final ]]; then
-        mkdir -p $out/lib
-        cp target/link.final $out/lib/link
-      fi
-      if [[ "$(ls -A target/lib)" ]]; then
-        mkdir -p $out/lib
-        cp target/lib/* $out/lib #*/
-        for lib in $out/lib/*.so $out/lib/*.dylib; do #*/
-          ln -s $lib $(echo $lib | sed -e "s/-${metadata}//")
-        done
-      fi
-      if [[ "$(ls -A target/build)" ]]; then # */
-        mkdir -p $out/lib
-        cp -r target/build/* $out/lib # */
-      fi
-      if [[ "$(ls -A target/bin)" ]]; then
-        mkdir -p $out/bin
-        cp -P target/bin/* $out/bin # */
-      fi
-      runHook postInstall
-    '';
-in
-
-crate_: lib.makeOverridable ({ rust, release, verbose, features, buildInputs, crateOverrides,
-  dependencies, buildDependencies,
-  extraRustcOpts,
-  preUnpack, postUnpack, prePatch, patches, postPatch,
-  preConfigure, postConfigure, preBuild, postBuild, preInstall, postInstall }:
-
-let crate = crate_ // (lib.attrByPath [ crate_.crateName ] (attr: {}) crateOverrides crate_);
-    dependencies_ = dependencies;
-    buildDependencies_ = buildDependencies;
-    processedAttrs = [
-      "src" "buildInputs" "crateBin" "crateLib" "libName" "libPath"
-      "buildDependencies" "dependencies" "features"
-      "crateName" "version" "build" "authors" "colors"
-    ];
-    extraDerivationAttrs = lib.filterAttrs (n: v: ! lib.elem n processedAttrs) crate;
-    buildInputs_ = buildInputs;
-in
-stdenv.mkDerivation (rec {
-
-    inherit (crate) crateName;
-    inherit preUnpack postUnpack prePatch patches postPatch preConfigure postConfigure preBuild postBuild preInstall postInstall;
-
-    src = if lib.hasAttr "src" crate then
-        crate.src
-      else
-        fetchCrate { inherit (crate) crateName version sha256; };
-    name = "rust_${crate.crateName}-${crate.version}";
-    buildInputs = [ rust ncurses ] ++ (crate.buildInputs or []) ++ buildInputs_;
-    dependencies =
-      builtins.map
-        (dep: dep.override { rust = rust; release = release; verbose = verbose; crateOverrides = crateOverrides; })
-        dependencies_;
-
-    buildDependencies =
-      builtins.map
-        (dep: dep.override { rust = rust; release = release; verbose = verbose; crateOverrides = crateOverrides; })
-        buildDependencies_;
-
-    completeDeps = lib.lists.unique (dependencies ++ lib.lists.concatMap (dep: dep.completeDeps) dependencies);
-    completeBuildDeps = lib.lists.unique (
-      buildDependencies
-      ++ lib.lists.concatMap (dep: dep.completeBuildDeps ++ dep.completeDeps) buildDependencies
-    );
-
-    crateFeatures = if crate ? features then
-        lib.concatMapStringsSep " " (f: "--cfg feature=\\\"${f}\\\"") (crate.features ++ features) #"
-      else "";
-
-    libName = if crate ? libName then crate.libName else crate.crateName;
-    libPath = if crate ? libPath then crate.libPath else "";
-
-    depsMetadata = builtins.foldl' (str: dep: str + dep.metadata) "" (dependencies ++ buildDependencies);
-    metadata = builtins.substring 0 10 (builtins.hashString "sha256" (crateName + "-" + crateVersion + "___" + toString crateFeatures + "___" + depsMetadata ));
-
-    crateBin = if crate ? crateBin then
-       builtins.foldl' (bins: bin: let
-            _name = (if bin ? name then bin.name else crateName);
-            name = lib.strings.replaceStrings ["-"] ["_"] _name;
-            path = if bin ? path then bin.path else "";
-          in
-          bins + (if bin == "" then "" else ",") + "${name} ${path}"
-
-       ) "" crate.crateBin
-    else "";
-
-    finalBins = if crate ? crateBin then
-       builtins.foldl' (bins: bin:
-          let name = lib.strings.replaceStrings ["-"] ["_"]
-                      (if bin ? name then bin.name else crateName);
-              new_name = if bin ? name then bin.name else crateName;
-          in
-          if name == new_name then bins else
-          (bins + "mv target/bin/${name} target/bin/${new_name};")
-
-       ) "" crate.crateBin
-    else "";
-
-    build = crate.build or "";
-    workspace_member = crate.workspace_member or ".";
-    crateVersion = crate.version;
-    crateAuthors = if crate ? authors && lib.isList crate.authors then crate.authors else [];
-    crateType =
-      if lib.attrByPath ["procMacro"] false crate then "proc-macro" else
-      if lib.attrByPath ["plugin"] false crate then "dylib" else
-      (crate.type or "lib");
-    colors = lib.attrByPath [ "colors" ] "always" crate;
-    extraLinkFlags = builtins.concatStringsSep " " (crate.extraLinkFlags or []);
-    configurePhase = configureCrate {
-      inherit crateName buildDependencies completeDeps completeBuildDeps
-              crateFeatures libName build workspace_member release libPath crateVersion
-              extraLinkFlags
-              crateAuthors verbose colors;
-    };
-    extraRustcOpts = if crate ? extraRustcOpts then crate.extraRustcOpts else [];
-    buildPhase = buildCrate {
-      inherit crateName dependencies
-              crateFeatures libName release libPath crateType
-              metadata crateBin finalBins verbose colors
-              extraRustcOpts;
-    };
-    installPhase = installCrate crateName metadata;
-
-} // extraDerivationAttrs
-)) {
-  rust = rustc;
-  release = crate_.release or true;
-  verbose = crate_.verbose or true;
-  extraRustcOpts = [];
-  features = [];
-  buildInputs = [];
-  crateOverrides = defaultCrateOverrides;
-  preUnpack = crate_.preUnpack or "";
-  postUnpack = crate_.postUnpack or "";
-  prePatch = crate_.prePatch or "";
-  patches = crate_.patches or [];
-  postPatch = crate_.postPatch or "";
-  preConfigure = crate_.preConfigure or "";
-  postConfigure = crate_.postConfigure or "";
-  preBuild = crate_.preBuild or "";
-  postBuild = crate_.postBuild or "";
-  preInstall = crate_.preInstall or "";
-  postInstall = crate_.postInstall or "";
-  dependencies = crate_.dependencies or [];
-  buildDependencies = crate_.buildDependencies or [];
-}
diff --git a/pkgs/build-support/rust/build-rust-crate/configure-crate.nix b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
new file mode 100644
index 00000000000..37fef2abd77
--- /dev/null
+++ b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
@@ -0,0 +1,129 @@
+{ lib, stdenv, echo_build_heading, noisily, makeDeps }:
+{ build, buildDependencies, colors, completeBuildDeps, completeDeps, crateAuthors, crateFeatures, crateName, crateVersion, extraLinkFlags, libName, libPath, release, target_os, verbose, workspace_member }:
+let version_ = lib.splitString "-" crateVersion;
+    versionPre = if lib.tail version_ == [] then "" else builtins.elemAt version_ 1;
+    version = lib.splitString "." (lib.head version_);
+    rustcOpts = (if release then "-C opt-level=3" else "-C debuginfo=2");
+    buildDeps = makeDeps buildDependencies;
+    authors = lib.concatStringsSep ":" crateAuthors;
+    optLevel = if release then 3 else 0;
+    completeDepsDir = lib.concatStringsSep " " completeDeps;
+    completeBuildDepsDir = lib.concatStringsSep " " completeBuildDeps;
+in ''
+  cd ${workspace_member}
+  runHook preConfigure
+  ${echo_build_heading colors}
+  ${noisily colors verbose}
+  symlink_dependency() {
+    # $1 is the nix-store path of a dependency
+    # $2 is the target path
+    i=$1
+    ln -s -f $i/lib/*.rlib $2 #*/
+    ln -s -f $i/lib/*.so $i/lib/*.dylib $2 #*/
+    if [ -e "$i/lib/link" ]; then
+        cat $i/lib/link >> target/link
+        cat $i/lib/link >> target/link.final
+    fi
+    if [ -e $i/env ]; then
+        source $i/env
+    fi
+  }
+
+  mkdir -p target/{deps,lib,build,buildDeps}
+  chmod uga+w target -R
+  echo ${extraLinkFlags} > target/link
+  echo ${extraLinkFlags} > target/link.final
+  for i in ${completeDepsDir}; do
+    symlink_dependency $i target/deps
+  done
+  for i in ${completeBuildDepsDir}; do
+     symlink_dependency $i target/buildDeps
+  done
+  if [[ -e target/link ]]; then
+    sort -u target/link > target/link.sorted
+    mv target/link.sorted target/link
+    sort -u target/link.final > target/link.final.sorted
+    mv target/link.final.sorted target/link.final
+    tr '\n' ' ' < target/link > target/link_
+  fi
+  EXTRA_BUILD=""
+  BUILD_OUT_DIR=""
+  export CARGO_PKG_NAME=${crateName}
+  export CARGO_PKG_VERSION=${crateVersion}
+  export CARGO_PKG_AUTHORS="${authors}"
+
+  export CARGO_CFG_TARGET_ARCH=${stdenv.hostPlatform.parsed.cpu.name}
+  export CARGO_CFG_TARGET_OS=${target_os}
+  export CARGO_CFG_TARGET_FAMILY="unix"
+  export CARGO_CFG_UNIX=1
+  export CARGO_CFG_TARGET_ENV="gnu"
+  export CARGO_CFG_TARGET_ENDIAN=${if stdenv.hostPlatform.parsed.cpu.significantByte.name == "littleEndian" then "little" else "big"}
+  export CARGO_CFG_TARGET_POINTER_WIDTH=${toString stdenv.hostPlatform.parsed.cpu.bits}
+  export CARGO_CFG_TARGET_VENDOR=${stdenv.hostPlatform.parsed.vendor.name}
+
+  export CARGO_MANIFEST_DIR="."
+  export DEBUG="${toString (!release)}"
+  export OPT_LEVEL="${toString optLevel}"
+  export TARGET="${stdenv.hostPlatform.config}"
+  export HOST="${stdenv.hostPlatform.config}"
+  export PROFILE=${if release then "release" else "debug"}
+  export OUT_DIR=$(pwd)/target/build/${crateName}.out
+  export CARGO_PKG_VERSION_MAJOR=${builtins.elemAt version 0}
+  export CARGO_PKG_VERSION_MINOR=${builtins.elemAt version 1}
+  export CARGO_PKG_VERSION_PATCH=${builtins.elemAt version 2}
+  if [[ -n "${versionPre}" ]]; then
+    export CARGO_PKG_VERSION_PRE="${versionPre}"
+  fi
+
+  BUILD=""
+  if [[ ! -z "${build}" ]] ; then
+     BUILD=${build}
+  elif [[ -e "build.rs" ]]; then
+     BUILD="build.rs"
+  fi
+  if [[ ! -z "$BUILD" ]] ; then
+     echo_build_heading "$BUILD" ${libName}
+     mkdir -p target/build/${crateName}
+     EXTRA_BUILD_FLAGS=""
+     if [ -e target/link_ ]; then
+       EXTRA_BUILD_FLAGS=$(cat target/link_)
+     fi
+     if [ -e target/link.build ]; then
+       EXTRA_BUILD_FLAGS="$EXTRA_BUILD_FLAGS $(cat target/link.build)"
+     fi
+     noisily rustc --crate-name build_script_build $BUILD --crate-type bin ${rustcOpts} \
+       ${crateFeatures} --out-dir target/build/${crateName} --emit=dep-info,link \
+       -L dependency=target/buildDeps ${buildDeps} --cap-lints allow $EXTRA_BUILD_FLAGS --color ${colors}
+
+     mkdir -p target/build/${crateName}.out
+     export RUST_BACKTRACE=1
+     BUILD_OUT_DIR="-L $OUT_DIR"
+     mkdir -p $OUT_DIR
+     target/build/${crateName}/build_script_build > target/build/${crateName}.opt
+     set +e
+     EXTRA_BUILD=$(sed -n "s/^cargo:rustc-flags=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
+     EXTRA_FEATURES=$(sed -n "s/^cargo:rustc-cfg=\(.*\)/--cfg \1/p" target/build/${crateName}.opt | tr '\n' ' ')
+     EXTRA_LINK=$(sed -n "s/^cargo:rustc-link-lib=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
+     EXTRA_LINK_SEARCH=$(sed -n "s/^cargo:rustc-link-search=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ' | sort -u)
+
+     for env in $(sed -n "s/^cargo:rustc-env=\(.*\)/\1/p" target/build/${crateName}.opt); do
+       export $env
+     done
+
+     CRATENAME=$(echo ${crateName} | sed -e "s/\(.*\)-sys$/\U\1/")
+     grep -P "^cargo:(?!(rustc-|warning=|rerun-if-changed=|rerun-if-env-changed))" target/build/${crateName}.opt \
+       | sed -e "s/cargo:\([^=]*\)=\(.*\)/export DEP_$(echo $CRATENAME)_\U\1\E=\2/" > target/env
+
+     set -e
+     if [[ -n "$(ls target/build/${crateName}.out)" ]]; then
+
+        if [[ -e "${libPath}" ]]; then
+           cp -r target/build/${crateName}.out/* $(dirname ${libPath}) #*/
+        else
+           cp -r target/build/${crateName}.out/* src #*/
+        fi
+     fi
+  fi
+  runHook postConfigure
+''
+
diff --git a/pkgs/build-support/rust/build-rust-crate/default.nix b/pkgs/build-support/rust/build-rust-crate/default.nix
new file mode 100644
index 00000000000..db7f72acfb9
--- /dev/null
+++ b/pkgs/build-support/rust/build-rust-crate/default.nix
@@ -0,0 +1,186 @@
+# Code for buildRustCrate, a Nix function that builds Rust code, just
+# like Cargo, but using Nix instead.
+#
+# This can be useful for deploying packages with NixOps, and to share
+# binary dependencies between projects.
+
+{ lib, stdenv, defaultCrateOverrides, fetchCrate, ncurses, rustc  }:
+
+let
+    # This doesn't appear to be officially documented anywhere yet.
+    # See https://github.com/rust-lang-nursery/rust-forge/issues/101.
+    target_os = if stdenv.hostPlatform.isDarwin
+      then "macos"
+      else stdenv.hostPlatform.parsed.kernel.name;
+
+    makeDeps = dependencies:
+      (lib.concatMapStringsSep " " (dep:
+        let extern = lib.strings.replaceStrings ["-"] ["_"] dep.libName; in
+        (if dep.crateType == "lib" then
+           " --extern ${extern}=${dep.out}/lib/lib${extern}-${dep.metadata}.rlib"
+         else
+           " --extern ${extern}=${dep.out}/lib/lib${extern}-${dep.metadata}${stdenv.hostPlatform.extensions.sharedLibrary}")
+      ) dependencies);
+
+    echo_build_heading = colors: ''
+      echo_build_heading() {
+       start=""
+       end=""
+       if [[ "${colors}" == "always" ]]; then
+         start="$(printf '\033[0;1;32m')" #set bold, and set green.
+         end="$(printf '\033[0m')" #returns to "normal"
+       fi
+       if (( $# == 1 )); then
+         echo "$start""Building $1""$end"
+       else
+         echo "$start""Building $1 ($2)""$end"
+       fi
+      }
+    '';
+    noisily = colors: verbose: ''
+      noisily() {
+        start=""
+        end=""
+        if [[ "${colors}" == "always" ]]; then
+          start="$(printf '\033[0;1;32m')" #set bold, and set green.
+          end="$(printf '\033[0m')" #returns to "normal"
+        fi
+	${lib.optionalString verbose ''
+            echo -n "$start"Running "$end"
+            echo $@
+	''}
+	$@
+      }
+    '';
+
+    configureCrate = import ./configure-crate.nix { inherit lib stdenv echo_build_heading noisily makeDeps; };
+    buildCrate = import ./build-crate.nix { inherit lib stdenv echo_build_heading noisily makeDeps; };
+    installCrate = import ./install-crate.nix;
+
+    in
+
+crate_: lib.makeOverridable ({ rust, release, verbose, features, buildInputs, crateOverrides,
+  dependencies, buildDependencies,
+  extraRustcOpts,
+  preUnpack, postUnpack, prePatch, patches, postPatch,
+  preConfigure, postConfigure, preBuild, postBuild, preInstall, postInstall }:
+
+let crate = crate_ // (lib.attrByPath [ crate_.crateName ] (attr: {}) crateOverrides crate_);
+    dependencies_ = dependencies;
+    buildDependencies_ = buildDependencies;
+    processedAttrs = [
+      "src" "buildInputs" "crateBin" "crateLib" "libName" "libPath"
+      "buildDependencies" "dependencies" "features"
+      "crateName" "version" "build" "authors" "colors"
+    ];
+    extraDerivationAttrs = lib.filterAttrs (n: v: ! lib.elem n processedAttrs) crate;
+    buildInputs_ = buildInputs;
+in
+stdenv.mkDerivation (rec {
+
+    inherit (crate) crateName;
+    inherit preUnpack postUnpack prePatch patches postPatch preConfigure postConfigure preBuild postBuild preInstall postInstall;
+
+    src = if lib.hasAttr "src" crate then
+        crate.src
+      else
+        fetchCrate { inherit (crate) crateName version sha256; };
+    name = "rust_${crate.crateName}-${crate.version}";
+    buildInputs = [ rust ncurses ] ++ (crate.buildInputs or []) ++ buildInputs_;
+    dependencies =
+      builtins.map
+        (dep: dep.override { rust = rust; release = release; verbose = verbose; crateOverrides = crateOverrides; })
+        dependencies_;
+
+    buildDependencies =
+      builtins.map
+        (dep: dep.override { rust = rust; release = release; verbose = verbose; crateOverrides = crateOverrides; })
+        buildDependencies_;
+
+    completeDeps = lib.lists.unique (dependencies ++ lib.lists.concatMap (dep: dep.completeDeps) dependencies);
+    completeBuildDeps = lib.lists.unique (
+      buildDependencies
+      ++ lib.lists.concatMap (dep: dep.completeBuildDeps ++ dep.completeDeps) buildDependencies
+    );
+
+    crateFeatures = if crate ? features then
+        lib.concatMapStringsSep " " (f: "--cfg feature=\\\"${f}\\\"") (crate.features ++ features) #"
+      else "";
+
+    libName = if crate ? libName then crate.libName else crate.crateName;
+    libPath = if crate ? libPath then crate.libPath else "";
+
+    depsMetadata = builtins.foldl' (str: dep: str + dep.metadata) "" (dependencies ++ buildDependencies);
+    metadata = builtins.substring 0 10 (builtins.hashString "sha256" (crateName + "-" + crateVersion + "___" + toString crateFeatures + "___" + depsMetadata ));
+
+    crateBin = if crate ? crateBin then
+       builtins.foldl' (bins: bin: let
+            _name = (if bin ? name then bin.name else crateName);
+            name = lib.strings.replaceStrings ["-"] ["_"] _name;
+            path = if bin ? path then bin.path else "";
+          in
+          bins + (if bin == "" then "" else ",") + "${name} ${path}"
+
+       ) "" crate.crateBin
+    else "";
+
+    finalBins = if crate ? crateBin then
+       builtins.foldl' (bins: bin:
+          let name = lib.strings.replaceStrings ["-"] ["_"]
+                      (if bin ? name then bin.name else crateName);
+              new_name = if bin ? name then bin.name else crateName;
+          in
+          if name == new_name then bins else
+          (bins + "mv target/bin/${name} target/bin/${new_name};")
+
+       ) "" crate.crateBin
+    else "";
+
+    build = crate.build or "";
+    workspace_member = crate.workspace_member or ".";
+    crateVersion = crate.version;
+    crateAuthors = if crate ? authors && lib.isList crate.authors then crate.authors else [];
+    crateType =
+      if lib.attrByPath ["procMacro"] false crate then "proc-macro" else
+      if lib.attrByPath ["plugin"] false crate then "dylib" else
+      (crate.type or "lib");
+    colors = lib.attrByPath [ "colors" ] "always" crate;
+    extraLinkFlags = builtins.concatStringsSep " " (crate.extraLinkFlags or []);
+    configurePhase = configureCrate {
+      inherit crateName buildDependencies completeDeps completeBuildDeps
+              crateFeatures libName build workspace_member release libPath crateVersion
+              extraLinkFlags
+              crateAuthors verbose colors target_os;
+    };
+    extraRustcOpts = if crate ? extraRustcOpts then crate.extraRustcOpts else [];
+    buildPhase = buildCrate {
+      inherit crateName dependencies
+              crateFeatures libName release libPath crateType
+              metadata crateBin finalBins verbose colors
+              extraRustcOpts;
+    };
+    installPhase = installCrate crateName metadata;
+
+} // extraDerivationAttrs
+)) {
+  rust = rustc;
+  release = crate_.release or true;
+  verbose = crate_.verbose or true;
+  extraRustcOpts = [];
+  features = [];
+  buildInputs = [];
+  crateOverrides = defaultCrateOverrides;
+  preUnpack = crate_.preUnpack or "";
+  postUnpack = crate_.postUnpack or "";
+  prePatch = crate_.prePatch or "";
+  patches = crate_.patches or [];
+  postPatch = crate_.postPatch or "";
+  preConfigure = crate_.preConfigure or "";
+  postConfigure = crate_.postConfigure or "";
+  preBuild = crate_.preBuild or "";
+  postBuild = crate_.postBuild or "";
+  preInstall = crate_.preInstall or "";
+  postInstall = crate_.postInstall or "";
+  dependencies = crate_.dependencies or [];
+  buildDependencies = crate_.buildDependencies or [];
+}
diff --git a/pkgs/build-support/rust/build-rust-crate/install-crate.nix b/pkgs/build-support/rust/build-rust-crate/install-crate.nix
new file mode 100644
index 00000000000..c41df34ca39
--- /dev/null
+++ b/pkgs/build-support/rust/build-rust-crate/install-crate.nix
@@ -0,0 +1,28 @@
+crateName: metadata:
+''
+  runHook preInstall
+  mkdir -p $out
+  if [[ -s target/env ]]; then
+    cp target/env $out/env
+  fi
+  if [[ -s target/link.final ]]; then
+    mkdir -p $out/lib
+    cp target/link.final $out/lib/link
+  fi
+  if [[ "$(ls -A target/lib)" ]]; then
+    mkdir -p $out/lib
+    cp target/lib/* $out/lib #*/
+    for lib in $out/lib/*.so $out/lib/*.dylib; do #*/
+      ln -s $lib $(echo $lib | sed -e "s/-${metadata}//")
+    done
+  fi
+  if [[ "$(ls -A target/build)" ]]; then # */
+    mkdir -p $out/lib
+    cp -r target/build/* $out/lib # */
+  fi
+  if [[ "$(ls -A target/bin)" ]]; then
+    mkdir -p $out/bin
+    cp -P target/bin/* $out/bin # */
+  fi
+  runHook postInstall
+''