Support allowSubstitutes attribute in structured attribute derivations

Hopefully fixes #3081 (didn't test).

src/libstore/build.cc

@@ -1197,7 +1197,7 @@ void DerivationGoal::haveDerivation()
     /* We are first going to try to create the invalid output paths
        through substitutes.  If that doesn't work, we'll build
        them. */
-    if (settings.useSubstitutes && drv->substitutesAllowed())
+    if (settings.useSubstitutes && parsedDrv->substitutesAllowed())
         for (auto & i : invalidOutputs)
             addWaitee(worker.makeSubstitutionGoal(i, buildMode == bmRepair ? Repair : NoRepair));
 

src/libstore/derivations.cc

@@ -36,12 +36,6 @@ Path BasicDerivation::findOutput(const string & id) const
 }
 
 
-bool BasicDerivation::substitutesAllowed() const
-{
-    return get(env, "allowSubstitutes", "1") == "1";
-}
-
-
 bool BasicDerivation::isBuiltin() const
 {
     return string(builder, 0, 8) == "builtin:";

src/libstore/derivations.hh

@@ -56,8 +56,6 @@ struct BasicDerivation
        the given derivation. */
     Path findOutput(const string & id) const;
 
-    bool substitutesAllowed() const;
-
     bool isBuiltin() const;
 
     /* Return true iff this is a fixed-output derivation. */

src/libstore/misc.cc

@@ -1,4 +1,5 @@
 #include "derivations.hh"
+#include "parsed-derivations.hh"
 #include "globals.hh"
 #include "local-store.hh"
 #include "store-api.hh"
@@ -189,6 +190,7 @@ void Store::queryMissing(const PathSet & targets,
             }
 
             Derivation drv = derivationFromPath(i2.first);
+            ParsedDerivation parsedDrv(i2.first, drv);
 
             PathSet invalid;
             for (auto & j : drv.outputs)
@@ -197,7 +199,7 @@ void Store::queryMissing(const PathSet & targets,
                     invalid.insert(j.second.path);
             if (invalid.empty()) return;
 
-            if (settings.useSubstitutes && drv.substitutesAllowed()) {
+            if (settings.useSubstitutes && parsedDrv.substitutesAllowed()) {
                 auto drvState = make_ref<Sync<DrvState>>(DrvState(invalid.size()));
                 for (auto & output : invalid)
                     pool.enqueue(std::bind(checkOutput, i2.first, make_ref<Derivation>(drv), output, drvState));

src/libstore/parsed-derivations.cc

@@ -108,4 +108,9 @@ bool ParsedDerivation::willBuildLocally() const
     return getBoolAttr("preferLocalBuild") && canBuildLocally();
 }
 
+bool ParsedDerivation::substitutesAllowed() const
+{
+    return getBoolAttr("allowSubstitutes", true);
+}
+
 }

src/libstore/parsed-derivations.hh

@@ -30,6 +30,8 @@ public:
     bool canBuildLocally() const;
 
     bool willBuildLocally() const;
+
+    bool substitutesAllowed() const;
 };
 
 }