From 19698d15ce44e51a4b875f1cae05af70ffc5656a Mon Sep 17 00:00:00 2001
From: Andreas Rammhold <andreas@rammhold.de>
Date: Tue, 28 Jan 2020 14:00:38 +0100
Subject: [PATCH 1/2] buildRustCrateTests: add regression test for #74071

---
 .../rust/build-rust-crate/test/default.nix    | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

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 cdffb30d9b3c..6aad02992c1b 100644
--- a/pkgs/build-support/rust/build-rust-crate/test/default.nix
+++ b/pkgs/build-support/rust/build-rust-crate/test/default.nix
@@ -199,6 +199,27 @@ let
           })
         ];
       };
+      # Regression test for https://github.com/NixOS/nixpkgs/issues/74071
+      # Whenevever a build.rs file is generating files those should not be overlayed onto the actual source dir
+      buildRsOutDirOverlay = {
+        src = symlinkJoin {
+          name = "buildrs-out-dir-overlay";
+          paths = [
+            (mkLib "src/lib.rs")
+            (mkFile "build.rs" ''
+              use std::env;
+              use std::ffi::OsString;
+              use std::fs;
+              use std::path::Path;
+              fn main() {
+                let out_dir = env::var_os("OUT_DIR").expect("OUT_DIR not set");
+                let out_file = Path::new(&out_dir).join("lib.rs");
+                fs::write(out_file, "invalid rust code!").expect("failed to write lib.rs");
+              }
+            '')
+          ];
+        };
+      };
     };
     brotliCrates = (callPackage ./brotli-crates.nix {});
   in lib.mapAttrs (key: value: mkTest (value // lib.optionalAttrs (!value?crateName) { crateName = key; })) cases // {

From a57d0fe0bba9a76d7185cb489bad9326dc3570fe Mon Sep 17 00:00:00 2001
From: Andreas Rammhold <andreas@rammhold.de>
Date: Tue, 28 Jan 2020 14:03:21 +0100
Subject: [PATCH 2/2] buildRustCrate: fix #78412

`build.rs` files might create files. Those files are supposed to go into
`OUT_DIR` (envirionment variable) and not be overlayed onto the source
tree.
---
 .../rust/build-rust-crate/configure-crate.nix            | 9 ---------
 1 file changed, 9 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 efc538f0fd61..c146ffef5ff6 100644
--- a/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
+++ b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
@@ -137,16 +137,7 @@ in ''
      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
 ''