Split `OutputsSpec` and `ExtendedOutputsSpec`, use the former more

`DerivedPath::Built` and `DerivationGoal` were previously using a
regular set with the convention that the empty set means all outputs.
But it is easy to forget about this rule when processing those sets.
Using `OutputSpec` forces us to get it right.

2 files changed, 7 insertions, 11 deletions

diff --git a/src/libexpr/flake/flakeref.cc b/src/libexpr/flake/flakeref.cc
index bc61e2c9a..08adbe0c9 100644
--- a/src/libexpr/flake/flakeref.cc
+++ b/src/libexpr/flake/flakeref.cc
@@ -245,7 +245,7 @@ std::tuple<FlakeRef, std::string, ExtendedOutputsSpec> parseFlakeRefWithFragment
     bool isFlake)
 {
     auto [prefix, extendedOutputsSpec] = ExtendedOutputsSpec::parse(url);
-    auto [flakeRef, fragment] = parseFlakeRefWithFragment(prefix, baseDir, allowMissing, isFlake);
+    auto [flakeRef, fragment] = parseFlakeRefWithFragment(std::string { prefix }, baseDir, allowMissing, isFlake);
     return {std::move(flakeRef), fragment, extendedOutputsSpec};
 }
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index a08fef011..9cff4b365 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -53,7 +53,7 @@ StringMap EvalState::realiseContext(const PathSet & context)
             [&](const NixStringContextElem::Built & b) {
                 drvs.push_back(DerivedPath::Built {
                     .drvPath = b.drvPath,
-                    .outputs = std::set { b.output },
+                    .outputs = OutputsSpec::Names { b.output },
                 });
                 ensureValid(b.drvPath);
             },
@@ -84,16 +84,12 @@ StringMap EvalState::realiseContext(const PathSet & context)
     store->buildPaths(buildReqs);
 
     /* Get all the output paths corresponding to the placeholders we had */
-    for (auto & [drvPath, outputs] : drvs) {
-        const auto outputPaths = store->queryDerivationOutputMap(drvPath);
-        for (auto & outputName : outputs) {
-            auto outputPath = get(outputPaths, outputName);
-            if (!outputPath)
-                debugThrowLastTrace(Error("derivation '%s' does not have an output named '%s'",
-                    store->printStorePath(drvPath), outputName));
+    for (auto & drv : drvs) {
+        auto outputs = resolveDerivedPath(*store, drv);
+        for (auto & [outputName, outputPath] : outputs) {
             res.insert_or_assign(
-                downstreamPlaceholder(*store, drvPath, outputName),
-                store->printStorePath(*outputPath)
+                downstreamPlaceholder(*store, drv.drvPath, outputName),
+                store->printStorePath(outputPath)
             );
         }
     }