From b52808f1ad485da9e6202ed840140e434ede3c00 Mon Sep 17 00:00:00 2001
From: Mario Rodas <marsam@users.noreply.github.com>
Date: Sun, 16 Aug 2020 10:00:00 -0500
Subject: [PATCH] buildRustPackage: add support for parallel build

---
 pkgs/build-support/rust/default.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pkgs/build-support/rust/default.nix b/pkgs/build-support/rust/default.nix
index c292b8ea4d43..f270fe97326c 100644
--- a/pkgs/build-support/rust/default.nix
+++ b/pkgs/build-support/rust/default.nix
@@ -181,7 +181,7 @@ stdenv.mkDerivation (args // {
       "CXX_${rust.toRustTarget stdenv.buildPlatform}"="${cxxForBuild}" \
       "CC_${rust.toRustTarget stdenv.hostPlatform}"="${ccForHost}" \
       "CXX_${rust.toRustTarget stdenv.hostPlatform}"="${cxxForHost}" \
-      cargo build \
+      cargo build -j $NIX_BUILD_CORES \
         ${stdenv.lib.optionalString (buildType == "release") "--release"} \
         --target ${rustTarget} \
         --frozen ${concatStringsSep " " cargoBuildFlags}
@@ -208,7 +208,7 @@ stdenv.mkDerivation (args // {
     ${stdenv.lib.optionalString (buildAndTestSubdir != null) "pushd ${buildAndTestSubdir}"}
     runHook preCheck
     echo "Running cargo test ${argstr} -- ''${checkFlags} ''${checkFlagsArray+''${checkFlagsArray[@]}}"
-    cargo test ${argstr} -- ''${checkFlags} ''${checkFlagsArray+"''${checkFlagsArray[@]}"}
+    cargo test -j $NIX_BUILD_CORES ${argstr} -- --test-threads=$NIX_BUILD_CORES ''${checkFlags} ''${checkFlagsArray+"''${checkFlagsArray[@]}"}
     runHook postCheck
     ${stdenv.lib.optionalString (buildAndTestSubdir != null) "popd"}
   '');