Make --keep-going work with drv that don't have a system

src/libstore/build-result.hh

@@ -36,6 +36,7 @@ struct BuildResult
         NotDeterministic,
         ResolvesToAlreadyValid,
         NoSubstituters,
+        NoBuilders,
     } status = MiscFailure;
 
     /**
@@ -64,6 +65,7 @@ struct BuildResult
                 case NotDeterministic: return "NotDeterministic";
                 case ResolvesToAlreadyValid: return "ResolvesToAlreadyValid";
                 case NoSubstituters: return "NoSubstituters";
+                case NoBuilders: return "NoBuilders";
                 default: return "Unknown";
             };
         }();

src/libstore/store-api.hh

@@ -61,6 +61,7 @@ MakeError(InvalidPath, Error);
 MakeError(Unsupported, Error);
 MakeError(SubstituteGone, Error);
 MakeError(SubstituterDisabled, Error);
+MakeError(BadSystem, Error);
 
 MakeError(InvalidStoreReference, Error);
 

src/libstore/unix/build/local-derivation-goal.cc

@@ -264,6 +264,10 @@ Goal::Co LocalDerivationGoal::tryLocalBuild()
         buildUser.reset();
         worker.permanentFailure = true;
         co_return done(BuildResult::InputRejected, {}, std::move(e));
+    } catch (BadSystem & e) {
+        outputLocks.unlock();
+        buildUser.reset();
+        co_return done(BuildResult::NoBuilders, {}, std::move(e));
     }
 
     started();
@@ -532,7 +536,7 @@ void LocalDerivationGoal::startBuilder()
 
     /* Right platform? */
     if (!parsedDrv->canBuildLocally(worker.store))
-        throw Error("a '%s' with features {%s} is required to build '%s', but I am a '%s' with features {%s}",
+        throw BadSystem("a '%s' with features {%s} is required to build '%s', but I am a '%s' with features {%s}",
             drv->platform,
             concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()),
             worker.store.printStorePath(drvPath),

tests/functional/keep-going.nix

@@ -0,0 +1,33 @@
+with import ./config.nix;
+
+rec {
+
+  # Hack to get the scheduler to do what we want: The `good` derivation can
+  # only be built after `delay_good` (which takes a long time to build) while
+  # the others don't have any dependency.
+  # This means that if we build this with parallelism (`-j2`), then we can be
+  # reasonably sure that the failing derivations will be scheduled _before_ the
+  # `good` one (and so we can check that `--keep-going` works fine)
+  delay_good = mkDerivation {
+    name = "delay-good";
+    buildCommand = "sleep 3; touch $out";
+  };
+
+  good = mkDerivation {
+    name = "good";
+    buildCommand = "mkdir $out; echo foo > $out/bar";
+    delay = delay_good;
+  };
+
+  failing = mkDerivation {
+    name = "failing";
+    buildCommand = false;
+  };
+
+  requiresFooSystemFeature = mkDerivation {
+    name = "requires-foo-system-feature";
+    buildCommand = "mkdir $out; echo foo > $out/bar";
+    requiredSystemFeatures = [ "foo" ];
+  };
+
+}

tests/functional/keep-going.sh

@@ -0,0 +1,14 @@
+source common.sh
+
+clearStore
+
+# XXX: These invocations of nix-build should always return 100 according to the manpage, but often return 1
+(! nix-build ./keep-going.nix -j2)
+(! nix-build ./keep-going.nix -A good -j0) || \
+    fail "Hello shouldn't have been built because of earlier errors"
+
+clearStore
+
+(! nix-build ./keep-going.nix --keep-going -j2)
+nix-build ./keep-going.nix -A good -j0 || \
+    fail "Hello should have been built despite the errors because of '--keep-going'"

tests/functional/meson.build

@@ -164,6 +164,7 @@ suites = [
       'debugger.sh',
       'extra-sandbox-profile.sh',
       'help.sh',
+      'keep-going.sh',
     ],
     'workdir': meson.current_source_dir(),
   },