Fixing NixOS#7479: DerivationOutput and DerivationType

See that issue for details on the general goal.

The `DerivationGoal::derivationType` field had a bogus initialization,
now caught, so I made it `std::optional`. I think NixOS#8829 can make it
non-optional again because it will ensure we always have the derivation
when we construct a `DerivationGoal`.

src/libexpr/primops.cc

@@ -1373,15 +1373,15 @@ drvName, Bindings * attrs, Value & v)
                 drv.env[i] = state.store->printStorePath(outPath);
                 drv.outputs.insert_or_assign(
                     i,
-                    DerivationOutputInputAddressed {
+                    DerivationOutput::InputAddressed {
                         .path = std::move(outPath),
                     });
             }
             break;
             ;
         case DrvHash::Kind::Deferred:
             for (auto & i : outputs) {
-                drv.outputs.insert_or_assign(i, DerivationOutputDeferred {});
+                drv.outputs.insert_or_assign(i, DerivationOutput::Deferred {});
             }
         }
     }

src/libstore/build/derivation-goal.cc

@@ -521,7 +521,7 @@ void DerivationGoal::inputsRealised()
             [&](const DerivationType::Impure &) {
                 return true;
             }
-        }, drvType.raw());
+        }, drvType.raw);
 
         if (resolveDrv && !fullDrv.inputDrvs.empty()) {
             experimentalFeatureSettings.require(Xp::CaDerivations);
@@ -996,10 +996,11 @@ void DerivationGoal::buildDone()
         }
 
         else {
+            assert(derivationType);
             st =
                 dynamic_cast<NotDeterministic*>(&e) ? BuildResult::NotDeterministic :
                 statusOk(status) ? BuildResult::OutputRejected :
-                !derivationType.isSandboxed() || diskFull ? BuildResult::TransientFailure :
+                !derivationType->isSandboxed() || diskFull ? BuildResult::TransientFailure :
                 BuildResult::PermanentFailure;
         }
 

src/libstore/build/derivation-goal.hh

@@ -184,7 +184,7 @@ struct DerivationGoal : public Goal
     /**
      * The sort of derivation we are building.
      */
-    DerivationType derivationType;
+    std::optional<DerivationType> derivationType;
 
     typedef void (DerivationGoal::*GoalState)();
     GoalState state;

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

@@ -195,7 +195,7 @@ void LocalDerivationGoal::tryLocalBuild()
         else if (settings.sandboxMode == smDisabled)
             useChroot = false;
         else if (settings.sandboxMode == smRelaxed)
-            useChroot = derivationType.isSandboxed() && !noChroot;
+            useChroot = derivationType->isSandboxed() && !noChroot;
     }
 
     auto & localStore = getLocalStore();
@@ -689,7 +689,7 @@ void LocalDerivationGoal::startBuilder()
                 "nogroup:x:65534:\n", sandboxGid()));
 
         /* Create /etc/hosts with localhost entry. */
-        if (derivationType.isSandboxed())
+        if (derivationType->isSandboxed())
             writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n::1 localhost\n");
 
         /* Make the closure of the inputs available in the chroot,
@@ -893,7 +893,7 @@ void LocalDerivationGoal::startBuilder()
            us.
         */
 
-        if (derivationType.isSandboxed())
+        if (derivationType->isSandboxed())
             privateNetwork = true;
 
         userNamespaceSync.create();
@@ -1121,7 +1121,7 @@ void LocalDerivationGoal::initEnv()
        derivation, tell the builder, so that for instance `fetchurl'
        can skip checking the output.  On older Nixes, this environment
        variable won't be set, so `fetchurl' will do the check. */
-    if (derivationType.isFixed()) env["NIX_OUTPUT_CHECKED"] = "1";
+    if (derivationType->isFixed()) env["NIX_OUTPUT_CHECKED"] = "1";
 
     /* *Only* if this is a fixed-output derivation, propagate the
        values of the environment variables specified in the
@@ -1132,7 +1132,7 @@ void LocalDerivationGoal::initEnv()
        to the builder is generally impure, but the output of
        fixed-output derivations is by definition pure (since we
        already know the cryptographic hash of the output). */
-    if (!derivationType.isSandboxed()) {
+    if (!derivationType->isSandboxed()) {
         for (auto & i : parsedDrv->getStringsAttr("impureEnvVars").value_or(Strings()))
             env[i] = getEnv(i).value_or("");
     }
@@ -1797,7 +1797,7 @@ void LocalDerivationGoal::runChild()
             /* Fixed-output derivations typically need to access the
                network, so give them access to /etc/resolv.conf and so
                on. */
-            if (!derivationType.isSandboxed()) {
+            if (!derivationType->isSandboxed()) {
                 // Only use nss functions to resolve hosts and
                 // services. Don’t use it for anything else that may
                 // be configured for this system. This limits the
@@ -2048,7 +2048,7 @@ void LocalDerivationGoal::runChild()
                     #include "sandbox-defaults.sb"
                     ;
 
-                if (!derivationType.isSandboxed())
+                if (!derivationType->isSandboxed())
                     sandboxProfile +=
                         #include "sandbox-network.sb"
                         ;
@@ -2599,7 +2599,7 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                 });
             },
 
-        }, output->raw());
+        }, output->raw);
 
         /* FIXME: set proper permissions in restorePath() so
             we don't have to do another traversal. */

src/libstore/derivations.cc

@@ -32,7 +32,7 @@ std::optional<StorePath> DerivationOutput::path(const Store & store, std::string
         [](const DerivationOutput::Impure &) -> std::optional<StorePath> {
             return std::nullopt;
         },
-    }, raw());
+    }, raw);
 }
 
 
@@ -60,7 +60,7 @@ bool DerivationType::isCA() const
         [](const Impure &) {
             return true;
         },
-    }, raw());
+    }, raw);
 }
 
 bool DerivationType::isFixed() const
@@ -75,7 +75,7 @@ bool DerivationType::isFixed() const
         [](const Impure &) {
             return false;
         },
-    }, raw());
+    }, raw);
 }
 
 bool DerivationType::hasKnownOutputPaths() const
@@ -90,7 +90,7 @@ bool DerivationType::hasKnownOutputPaths() const
         [](const Impure &) {
             return false;
         },
-    }, raw());
+    }, raw);
 }
 
 
@@ -106,7 +106,7 @@ bool DerivationType::isSandboxed() const
         [](const Impure &) {
             return false;
         },
-    }, raw());
+    }, raw);
 }
 
 
@@ -122,7 +122,7 @@ bool DerivationType::isPure() const
         [](const Impure &) {
             return false;
         },
-    }, raw());
+    }, raw);
 }
 
 
@@ -408,13 +408,13 @@ std::string Derivation::unparse(const Store & store, bool maskOutputs,
                 s += ','; printUnquotedString(s, "");
                 s += ','; printUnquotedString(s, "");
             },
-            [&](const DerivationOutputImpure & doi) {
+            [&](const DerivationOutput::Impure & doi) {
                 // FIXME
                 s += ','; printUnquotedString(s, "");
                 s += ','; printUnquotedString(s, doi.method.renderPrefix() + printHashType(doi.hashType));
                 s += ','; printUnquotedString(s, "impure");
             }
-        }, i.second.raw());
+        }, i.second.raw);
         s += ')';
     }
 
@@ -509,7 +509,7 @@ DerivationType BasicDerivation::type() const
             [&](const DerivationOutput::Impure &) {
                 impureOutputs.insert(i.first);
             },
-        }, i.second.raw());
+        }, i.second.raw);
     }
 
     if (inputAddressedOutputs.empty()
@@ -626,7 +626,7 @@ DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOut
     if (type.isFixed()) {
         std::map<std::string, Hash> outputHashes;
         for (const auto & i : drv.outputs) {
-            auto & dof = std::get<DerivationOutput::CAFixed>(i.second.raw());
+            auto & dof = std::get<DerivationOutput::CAFixed>(i.second.raw);
             auto hash = hashString(htSHA256, "fixed:out:"
                 + dof.ca.printMethodAlgo() + ":"
                 + dof.ca.hash.to_string(Base16, false) + ":"
@@ -663,7 +663,7 @@ DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOut
         [](const DerivationType::Impure &) -> DrvHash::Kind {
             assert(false);
         }
-    }, drv.type().raw());
+    }, drv.type().raw);
 
     std::map<std::string, StringSet> inputs2;
     for (auto & [drvPath, inputOutputs0] : drv.inputDrvs) {
@@ -720,10 +720,10 @@ StringSet BasicDerivation::outputNames() const
 DerivationOutputsAndOptPaths BasicDerivation::outputsAndOptPaths(const Store & store) const
 {
     DerivationOutputsAndOptPaths outsAndOptPaths;
-    for (auto output : outputs)
+    for (auto & [outputName, output] : outputs)
         outsAndOptPaths.insert(std::make_pair(
-            output.first,
-            std::make_pair(output.second, output.second.path(store, name, output.first))
+            outputName,
+            std::make_pair(output.raw, output.path(store, name, outputName))
             )
         );
     return outsAndOptPaths;
@@ -798,7 +798,7 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
                     << (doi.method.renderPrefix() + printHashType(doi.hashType))
                     << "impure";
             },
-        }, i.second.raw());
+        }, i.second.raw);
     }
     WorkerProto::write(store,
         WorkerProto::WriteConn { .to = out },
@@ -840,7 +840,7 @@ static void rewriteDerivation(Store & store, BasicDerivation & drv, const String
 
     auto hashModulo = hashDerivationModulo(store, Derivation(drv), true);
     for (auto & [outputName, output] : drv.outputs) {
-        if (std::holds_alternative<DerivationOutput::Deferred>(output.raw())) {
+        if (std::holds_alternative<DerivationOutput::Deferred>(output.raw)) {
             auto h = get(hashModulo.hashes, outputName);
             if (!h)
                 throw Error("derivation '%s' output '%s' has no hash (derivations.cc/rewriteDerivation)",
@@ -955,7 +955,7 @@ void Derivation::checkInvariants(Store & store, const StorePath & drvPath) const
             [&](const DerivationOutput::Impure &) {
                 /* Nothing to check */
             },
-        }, i.second.raw());
+        }, i.second.raw);
     }
 }
 
@@ -984,7 +984,7 @@ nlohmann::json DerivationOutput::toJSON(
             res["hashAlgo"] = doi.method.renderPrefix() + printHashType(doi.hashType);
             res["impure"] = true;
         },
-    }, raw());
+    }, raw);
     return res;
 }