From d8b853799d6658582a6039be8febfbd925d967aa Mon Sep 17 00:00:00 2001
From: Symphorien Gibol <symphorien+git@xlumurb.eu>
Date: Wed, 25 Mar 2020 12:00:00 +0000
Subject: [PATCH 1/2] buildRustCrate: don't sort link flags

Linkage order is significant and sorting can result in link errors.
---
 pkgs/build-support/rust/build-rust-crate/configure-crate.nix | 2 +-
 pkgs/build-support/rust/build-rust-crate/lib.sh              | 5 -----
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/pkgs/build-support/rust/build-rust-crate/configure-crate.nix b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
index 61c39c6b21c0..ed8100537090 100644
--- a/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
+++ b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
@@ -172,7 +172,7 @@ in ''
      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/${crateName}.opt | tr '\n' ' ' | sort -u)
+     EXTRA_LINK=$(sed -n "s/^cargo:rustc-link-lib=\(.*\)/\1/p" target/build/${crateName}.opt | tr '\n' ' ')
      EXTRA_LINK_SEARCH=$(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
diff --git a/pkgs/build-support/rust/build-rust-crate/lib.sh b/pkgs/build-support/rust/build-rust-crate/lib.sh
index 5843ee98b0d5..6cf3481754b2 100644
--- a/pkgs/build-support/rust/build-rust-crate/lib.sh
+++ b/pkgs/build-support/rust/build-rust-crate/lib.sh
@@ -105,11 +105,6 @@ setup_link_paths() {
   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

From 2f7fb1c49732105c8937b66b7d92402c04546073 Mon Sep 17 00:00:00 2001
From: Symphorien Gibol <symphorien+git@xlumurb.eu>
Date: Sat, 28 Mar 2020 12:00:00 +0000
Subject: [PATCH 2/2] buildRustCrateTests: add regression test for link order

---
 .../rust/build-rust-crate/test/default.nix    | 54 ++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/pkgs/build-support/rust/build-rust-crate/test/default.nix b/pkgs/build-support/rust/build-rust-crate/test/default.nix
index f24583c41fcb..2251a1b40f2e 100644
--- a/pkgs/build-support/rust/build-rust-crate/test/default.nix
+++ b/pkgs/build-support/rust/build-rust-crate/test/default.nix
@@ -1,4 +1,4 @@
-{ lib, buildRustCrate, runCommand, writeTextFile, symlinkJoin, callPackage, releaseTools }:
+{ lib, buildRustCrate, runCommand, runCommandCC, writeTextFile, symlinkJoin, callPackage, releaseTools }:
 let
   mkCrate = args: let
     p = {
@@ -258,6 +258,58 @@ let
           ];
         };
       };
+      # Regression test for https://github.com/NixOS/nixpkgs/pull/83379
+      # link flag order should be preserved
+      linkOrder = {
+        src = symlinkJoin {
+          name = "buildrs-out-dir-overlay";
+          paths = [
+            (mkFile "build.rs" ''
+              fn main() {
+                // in the other order, linkage will fail
+                println!("cargo:rustc-link-lib=b");
+                println!("cargo:rustc-link-lib=a");
+              }
+            '')
+            (mkFile "src/main.rs" ''
+              extern "C" {
+                fn hello_world();
+              }
+              fn main() {
+                unsafe {
+                  hello_world();
+                }
+              }
+            '')
+          ];
+        };
+        buildInputs = let
+          compile = name: text: runCommandCC name {} ''
+            mkdir -p $out/lib
+            $CC -shared -o $out/lib/${name}.so ${writeTextFile {
+              name = "${name}-src.c";
+              inherit text;
+            }}
+          '';
+          b = compile "libb" ''
+            #include <stdio.h>
+
+            void hello();
+
+            void hello_world() {
+              hello();
+              printf(" world!\n");
+            }
+          '';
+          a = compile "liba" ''
+            #include <stdio.h>
+
+            void hello() {
+              printf("hello");
+            }
+          '';
+        in [ a b ];
+      };
       rustCargoTomlInSubDir = {
         # The "workspace_member" can be set to the sub directory with the crate to build.
         # By default ".", meaning the top level directory is assumed.