Get rid of `basicDerivation::findOutput`

It's a tiny function which is:

 - hardly worth abstrating over, and also only used once.

 - doesn't work once we get CA drvs

I rewrote the one callsite to be forwards compatable with CA
derivations, and also potentially more performant: instead of reading in
the derivation it can ust consult the SQLite DB in the common case.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 5795c2c09..ddd036070 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -381,7 +381,8 @@ static void queryInstSources(EvalState & state,
 
                 if (path.isDerivation()) {
                     elem.setDrvPath(state.store->printStorePath(path));
-                    elem.setOutPath(state.store->printStorePath(state.store->derivationFromPath(path).findOutput("out")));
+                    auto outputs = state.store->queryDerivationOutputMap(path);
+                    elem.setOutPath(state.store->printStorePath(outputs.at("out")));
                     if (name.size() >= drvExtension.size() &&
                         string(name, name.size() - drvExtension.size()) == drvExtension)
                         name = string(name, 0, name.size() - drvExtension.size());