Merge pull request #7667 from dramforever/flake-search-attr

Better error message for nix search when attr is not found

src/libcmd/installables.cc

@@ -379,10 +379,9 @@ Installable::getCursors(EvalState & state)
 ref<eval_cache::AttrCursor>
 Installable::getCursor(EvalState & state)
 {
- auto cursors = getCursors(state);
- if (cursors.empty())
- throw Error("cannot find flake attribute '%s'", what());
- return cursors[0];
+ /* Although getCursors should return at least one element, in case it doesn't,
+ bound check to avoid an undefined behavior for vector[0] */
+ return getCursors(state).at(0);
 }
 
 static StorePath getDeriver(
@@ -696,46 +695,28 @@ InstallableFlake::getCursors(EvalState & state)
 
  std::vector<ref<eval_cache::AttrCursor>> res;
 
- for (auto & attrPath : getActualAttrPaths()) {
- auto attr = root->findAlongAttrPath(parseAttrPath(state, attrPath));
- if (attr) res.push_back(ref(*attr));
- }
-
- return res;
-}
-
-ref<eval_cache::AttrCursor> InstallableFlake::getCursor(EvalState & state)
-{
- auto lockedFlake = getLockedFlake();
-
- auto cache = openEvalCache(state, lockedFlake);
- auto root = cache->getRoot();
-
  Suggestions suggestions;
-
  auto attrPaths = getActualAttrPaths();
 
  for (auto & attrPath : attrPaths) {
  debug("trying flake output attribute '%s'", attrPath);
 
- auto attrOrSuggestions = root->findAlongAttrPath(
- parseAttrPath(state, attrPath),
- true
- );
-
- if (!attrOrSuggestions) {
- suggestions += attrOrSuggestions.getSuggestions();
- continue;
+ auto attr = root->findAlongAttrPath(parseAttrPath(state, attrPath));
+ if (attr) {
+ res.push_back(ref(*attr));
+ } else {
+ suggestions += attr.getSuggestions();
  }
-
- return *attrOrSuggestions;
  }
 
- throw Error(
- suggestions,
- "flake '%s' does not provide attribute %s",
- flakeRef,
- showAttrPaths(attrPaths));
+ if (res.size() == 0)
+ throw Error(
+ suggestions,
+ "flake '%s' does not provide attribute %s",
+ flakeRef,
+ showAttrPaths(attrPaths));
+
+ return res;
 }
 
 std::shared_ptr<flake::LockedFlake> InstallableFlake::getLockedFlake() const

src/libcmd/installables.hh

@@ -103,9 +103,13 @@ struct Installable
  return {};
  }
 
+ /* Get a cursor to each value this Installable could refer to. However
+ if none exists, throw exception instead of returning empty vector. */
  virtual std::vector<ref<eval_cache::AttrCursor>>
  getCursors(EvalState & state);
 
+ /* Get the first and most preferred cursor this Installable could refer
+ to, or throw an exception if none exists. */
  virtual ref<eval_cache::AttrCursor>
  getCursor(EvalState & state);
 
@@ -193,15 +197,11 @@ struct InstallableFlake : InstallableValue
 
  std::pair<Value *, PosIdx> toValue(EvalState & state) override;
 
- /* Get a cursor to every attrpath in getActualAttrPaths() that
- exists. */
+ /* Get a cursor to every attrpath in getActualAttrPaths()
+ that exists. However if none exists, throw an exception. */
  std::vector<ref<eval_cache::AttrCursor>>
  getCursors(EvalState & state) override;
 
- /* Get a cursor to the first attrpath in getActualAttrPaths() that
- exists, or throw an exception with suggestions if none exists. */
- ref<eval_cache::AttrCursor> getCursor(EvalState & state) override;
-
  std::shared_ptr<flake::LockedFlake> getLockedFlake() const;
 
  FlakeRef nixpkgsFlakeRef() const override;

src/nix/search.cc

@@ -56,8 +56,8 @@ struct CmdSearch : InstallableCommand, MixJSON
  Strings getDefaultFlakeAttrPaths() override
  {
  return {
- "packages." + settings.thisSystem.get() + ".",
- "legacyPackages." + settings.thisSystem.get() + "."
+ "packages." + settings.thisSystem.get(),
+ "legacyPackages." + settings.thisSystem.get()
  };
  }