Merge pull request #4257 from hercules-ci/issue-4197-nix-build-output-order

Issue 4197 nix build output order

src/nix-build/nix-build.cc

@@ -487,6 +487,7 @@ static void main_nix_build(int argc, char * * argv)
     else {
 
         std::vector<StorePathWithOutputs> pathsToBuild;
+        std::vector<std::pair<StorePath, std::string>> pathsToBuildOrdered;
 
         std::map<StorePath, std::pair<size_t, StringSet>> drvMap;
 
@@ -498,6 +499,7 @@ static void main_nix_build(int argc, char * * argv)
                 throw Error("derivation '%s' lacks an 'outputName' attribute", store->printStorePath(drvPath));
 
             pathsToBuild.push_back({drvPath, {outputName}});
+            pathsToBuildOrdered.push_back({drvPath, {outputName}});
 
             auto i = drvMap.find(drvPath);
             if (i != drvMap.end())
@@ -513,15 +515,14 @@ static void main_nix_build(int argc, char * * argv)
 
         std::vector<StorePath> outPaths;
 
-        for (auto & [drvPath, info] : drvMap) {
+        for (auto & [drvPath, outputName] : pathsToBuildOrdered) {
-            auto & [counter, wantedOutputs] = info;
+            auto & [counter, _wantedOutputs] = drvMap.at({drvPath});
             std::string drvPrefix = outLink;
             if (counter)
                 drvPrefix += fmt("-%d", counter + 1);
 
             auto builtOutputs = store->queryDerivationOutputMap(drvPath);
 
-            for (auto & outputName : wantedOutputs) {
             auto outputPath = builtOutputs.at(outputName);
 
             if (auto store2 = store.dynamic_pointer_cast<LocalFSStore>()) {
@@ -532,7 +533,6 @@ static void main_nix_build(int argc, char * * argv)
 
             outPaths.push_back(outputPath);
         }
-        }
 
         logger->stop();
 

tests/nix-build-examples.nix

@@ -0,0 +1,33 @@
+with import ./config.nix;
+
+rec {
+
+  input0 = mkDerivation {
+    name = "dependencies-input-0";
+    buildCommand = "mkdir $out; echo foo > $out/bar";
+  };
+
+  input1 = mkDerivation {
+    name = "dependencies-input-1";
+    buildCommand = "mkdir $out; echo FOO > $out/foo";
+  };
+
+  input2 = mkDerivation {
+    name = "dependencies-input-2";
+    buildCommand = ''
+      mkdir $out
+      echo BAR > $out/bar
+      echo ${input0} > $out/input0
+    '';
+  };
+
+  body = mkDerivation {
+    name = "dependencies-top";
+    builder = ./dependencies.builder0.sh + "/FOOBAR/../.";
+    input1 = input1 + "/.";
+    input2 = "${input2}/.";
+    input1_drv = input1;
+    meta.description = "Random test package";
+  };
+
+}

tests/nix-build.sh

@@ -26,3 +26,18 @@ outPath2=$(nix-build $(nix-instantiate dependencies.nix)!out --no-out-link)
 
 outPath2=$(nix-store -r $(nix-instantiate --add-root $TEST_ROOT/indirect dependencies.nix)!out)
 [[ $outPath = $outPath2 ]]
+
+# The order of the paths on stdout must correspond to the -A options
+# https://github.com/NixOS/nix/issues/4197
+
+input0="$(nix-build nix-build-examples.nix -A input0 --no-out-link)"
+input1="$(nix-build nix-build-examples.nix -A input1 --no-out-link)"
+input2="$(nix-build nix-build-examples.nix -A input2 --no-out-link)"
+body="$(nix-build nix-build-examples.nix -A body --no-out-link)"
+
+outPathsA="$(echo $(nix-build nix-build-examples.nix -A input0 -A input1 -A input2 -A body --no-out-link))"
+[[ "$outPathsA" = "$input0 $input1 $input2 $body" ]]
+
+# test a different ordering to make sure it fails, not just in 23 out of 24 permutations
+outPathsB="$(echo $(nix-build nix-build-examples.nix -A body -A input1 -A input2 -A input0 --no-out-link))"
+[[ "$outPathsB" = "$body $input1 $input2 $input0" ]]