Retry substitution after an incomplete closure only once

This avoids an infinite loop in the final test in
tests/binary-cache.sh. I think this was only not triggered previously
by accident (because we were clearing wantedOutputs in between).

2 files changed, 8 insertions, 5 deletions

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 7dc5737fb..3d1c4fbc1 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -207,8 +207,6 @@ void DerivationGoal::haveDerivation()
     if (!drv->type().hasKnownOutputPaths())
         settings.requireExperimentalFeature(Xp::CaDerivations);
 
-    retrySubstitution = false;
-
     for (auto & i : drv->outputsAndOptPaths(worker.store))
         if (i.second.second)
             worker.store.addTempRoot(*i.second.second);
@@ -423,7 +421,8 @@ void DerivationGoal::inputsRealised()
         return;
     }
 
-    if (retrySubstitution) {
+    if (retrySubstitution && !retriedSubstitution) {
+        retriedSubstitution = true;
         haveDerivation();
         return;
     }
diff --git a/src/libstore/build/derivation-goal.hh b/src/libstore/build/derivation-goal.hh
index ea2db89b2..f556b6f25 100644
--- a/src/libstore/build/derivation-goal.hh
+++ b/src/libstore/build/derivation-goal.hh
@@ -61,8 +61,12 @@ struct DerivationGoal : public Goal
     bool needRestart = false;
 
     /* Whether to retry substituting the outputs after building the
-       inputs. */
-    bool retrySubstitution;
+       inputs. This is done in case of an incomplete closure. */
+    bool retrySubstitution = false;
+
+    /* Whether we've retried substitution, in which case we won't try
+       again. */
+    bool retriedSubstitution = false;
 
     /* The derivation stored at drvPath. */
     std::unique_ptr<Derivation> drv;