More properly track the status of CA builds

Make the build of unresolved derivations return the same status as the
resolved one, except in the case of an `AlreadyValid` in which case it
will return `ResolvesToAlreadyValid` to mean that the outputs of the unresolved
derivation weren’t known, but the resolved one is.

src/libstore/build/derivation-goal.cc

@@ -464,7 +464,6 @@ void DerivationGoal::inputsRealised()
  Derivation drvResolved { *std::move(attempt) };
 
  auto pathResolved = writeDerivation(worker.store, drvResolved);
- resolvedDrv = drvResolved;
 
  auto msg = fmt("Resolved derivation: '%s' -> '%s'",
  worker.store.printStorePath(drvPath),
@@ -475,9 +474,9 @@ void DerivationGoal::inputsRealised()
  worker.store.printStorePath(pathResolved),
  });
 
- auto resolvedGoal = worker.makeDerivationGoal(
+ resolvedDrvGoal = worker.makeDerivationGoal(
  pathResolved, wantedOutputs, buildMode);
- addWaitee(resolvedGoal);
+ addWaitee(resolvedDrvGoal);
 
  state = &DerivationGoal::resolvedFinished;
  return;
@@ -938,16 +937,17 @@ void DerivationGoal::buildDone()
 }
 
 void DerivationGoal::resolvedFinished() {
- assert(resolvedDrv);
+ assert(resolvedDrvGoal);
+ auto resolvedDrv = *resolvedDrvGoal->drv;
 
- auto resolvedHashes = staticOutputHashes(worker.store, *resolvedDrv);
+ auto resolvedHashes = staticOutputHashes(worker.store, resolvedDrv);
 
  StorePathSet outputPaths;
 
  // `wantedOutputs` might be empty, which means “all the outputs”
  auto realWantedOutputs = wantedOutputs;
  if (realWantedOutputs.empty())
- realWantedOutputs = resolvedDrv->outputNames();
+ realWantedOutputs = resolvedDrv.outputNames();
 
  for (auto & wantedOutput : realWantedOutputs) {
  assert(initialOutputs.count(wantedOutput) != 0);
@@ -979,9 +979,17 @@ void DerivationGoal::resolvedFinished() {
  outputPaths
  );
 
- // This is potentially a bit fishy in terms of error reporting. Not sure
- // how to do it in a cleaner way
- amDone(nrFailed == 0 ? ecSuccess : ecFailed, ex);
+ auto status = [&]() {
+ auto resolvedResult = resolvedDrvGoal->getResult();
+ switch (resolvedResult.status) {
+ case BuildResult::AlreadyValid:
+ return BuildResult::ResolvesToAlreadyValid;
+ default:
+ return resolvedResult.status;
+ }
+ }();
+
+ done(status);
 }
 
 HookReply DerivationGoal::tryBuildHook()

src/libstore/build/derivation-goal.hh

@@ -50,8 +50,8 @@ struct DerivationGoal : public Goal
  /* The path of the derivation. */
  StorePath drvPath;
 
- /* The path of the corresponding resolved derivation */
- std::optional<BasicDerivation> resolvedDrv;
+ /* The goal for the corresponding resolved derivation */
+ std::shared_ptr<DerivationGoal> resolvedDrvGoal;
 
  /* The specific outputs that we need to build. Empty means all of
  them. */

src/libstore/store-api.hh

@@ -151,6 +151,7 @@ struct BuildResult
  DependencyFailed,
  LogLimitExceeded,
  NotDeterministic,
+ ResolvesToAlreadyValid,
  } status = MiscFailure;
  std::string errorMsg;
 
@@ -170,7 +171,7 @@ struct BuildResult
  time_t startTime = 0, stopTime = 0;
 
  bool success() {
- return status == Built || status == Substituted || status == AlreadyValid;
+ return status == Built || status == Substituted || status == AlreadyValid || status == ResolvesToAlreadyValid;
  }
 };