Clean up app.cc (#9201)

- Rename `expected` to `expectedType`

- Use early `return` and `continue` to reduce nesting

.gitignore

@@ -138,7 +138,9 @@ nix-rust/target
 
 result
 
+# IDE
 .vscode/
+.idea/
 
 # clangd and possibly more
 .cache/

src/nix/app.cc

@@ -20,10 +20,16 @@ StringPairs resolveRewrites(
     const std::vector<BuiltPathWithResult> & dependencies)
 {
     StringPairs res;
-    if (experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
+    if (!experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
+        return res;
+    }
     for (auto &dep: dependencies) {
-            if (auto drvDep = std::get_if<BuiltPathBuilt>(&dep.path)) {
+        auto drvDep = std::get_if<BuiltPathBuilt>(&dep.path);
-                for (auto & [ outputName, outputPath ] : drvDep->outputs) {
+        if (!drvDep) {
+            continue;
+        }
+
+        for (const auto & [ outputName, outputPath ] : drvDep->outputs) {
             res.emplace(
                 DownstreamPlaceholder::fromSingleDerivedPathBuilt(
                     SingleDerivedPath::Built {
@@ -34,8 +40,6 @@ StringPairs resolveRewrites(
             );
         }
     }
-        }
-    }
     return res;
 }
 
@@ -58,11 +62,11 @@ UnresolvedApp InstallableValue::toApp(EvalState & state)
 
     auto type = cursor->getAttr("type")->getString();
 
-    std::string expected = !attrPath.empty() &&
+    std::string expectedType = !attrPath.empty() &&
         (state.symbols[attrPath[0]] == "apps" || state.symbols[attrPath[0]] == "defaultApp")
         ? "app" : "derivation";
-    if (type != expected)
+    if (type != expectedType)
-        throw Error("attribute '%s' should have type '%s'", cursor->getAttrPathStr(), expected);
+        throw Error("attribute '%s' should have type '%s'", cursor->getAttrPathStr(), expectedType);
 
     if (type == "app") {
         auto [program, context] = cursor->getAttr("program")->getStringWithContext();