Remove registerOutputs from drv goal

Easy to inline in one spot, and assert in the other.

src/libstore/build/derivation-goal.cc

@@ -945,7 +945,15 @@ Goal::Co DerivationGoal::hookDone()
 
         /* Compute the FS closure of the outputs and register them as
            being valid. */
-        auto builtOutputs = registerOutputs();
+        auto builtOutputs =
+            /* When using a build hook, the build hook can register the output
+               as valid (by doing `nix-store --import').  If so we don't have
+               to do anything here.
+
+               We can only early return when the outputs are known a priori. For
+               floating content-addressing derivations this isn't the case.
+             */
+            assertPathValidity();
 
         StorePathSet outputPaths;
         for (auto & [_, output] : builtOutputs)
@@ -1174,18 +1182,6 @@ HookReply DerivationGoal::tryBuildHook()
 }
 
 
-SingleDrvOutputs DerivationGoal::registerOutputs()
-{
-    /* When using a build hook, the build hook can register the output
-       as valid (by doing `nix-store --import').  If so we don't have
-       to do anything here.
-
-       We can only early return when the outputs are known a priori. For
-       floating content-addressing derivations this isn't the case.
-     */
-    return assertPathValidity();
-}
-
 Path DerivationGoal::openLogFile()
 {
     logSize = 0;

src/libstore/build/derivation-goal.hh

@@ -262,12 +262,6 @@ struct DerivationGoal : public Goal
      */
     HookReply tryBuildHook();
 
-    /**
-     * Check that the derivation outputs all exist and register them
-     * as valid.
-     */
-    virtual SingleDrvOutputs registerOutputs();
-
     /**
      * Open a log file and a pipe to it.
      */

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

@@ -2330,15 +2330,7 @@ void LocalDerivationGoal::runChild()
 
 SingleDrvOutputs LocalDerivationGoal::registerOutputs()
 {
-    /* When using a build hook, the build hook can register the output
-       as valid (by doing `nix-store --import').  If so we don't have
-       to do anything here.
-
-       We can only early return when the outputs are known a priori. For
-       floating content-addressing derivations this isn't the case.
-     */
-    if (hook)
-        return DerivationGoal::registerOutputs();
+    assert(!hook);
 
     std::map<std::string, ValidPathInfo> infos;
 

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

@@ -239,7 +239,7 @@ struct LocalDerivationGoal : public DerivationGoal
      * Check that the derivation outputs all exist and register them
      * as valid.
      */
-    SingleDrvOutputs registerOutputs() override;
+    SingleDrvOutputs registerOutputs();
 
     void signRealisation(Realisation &) override;