refactor(features2): new variant FeaturesFor::ArtifactDep

As the existence of `FeaturesFor` is acting as a key that discriminate
activated features for the same package with different circumstances.
Artifact dependencies deserve its own variant and it makes things clear to me.

- ✏️ `NormalOrDevOrArtifactTarget(CompileTarget)` ->  `NormalOrDev`
- 🆕 `ArtifactDep(target)`

src/cargo/core/compiler/standard_lib.rs

@@ -193,10 +193,7 @@ pub fn generate_std_roots(
  // in time is minimal, and the difference in caching is
  // significant.
  let mode = CompileMode::Build;
- let features = std_features.activated_features(
- pkg.package_id(),
- FeaturesFor::NormalOrDevOrArtifactTarget(None),
- );
+ let features = std_features.activated_features(pkg.package_id(), FeaturesFor::NormalOrDev);
  for kind in kinds {
  let list = ret.entry(*kind).or_insert_with(Vec::new);
  let unit_for = UnitFor::new_normal(*kind);

src/cargo/core/resolver/features.rs

@@ -95,30 +95,29 @@ pub enum ForceAllTargets {
  No,
 }
 
-/// Flag to indicate if features are requested for a build dependency or not.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Hash)]
+/// Flag to indicate if features are requested for a certain type of dependency.
+///
+/// This is primarily used for constructing a [`PackageFeaturesKey`] to decouple
+/// activated features of the same package with different types of dependency.
+#[derive(Default, Copy, Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Hash)]
 pub enum FeaturesFor {
- /// If `Some(target)` is present, we represent an artifact target.
- /// Otherwise any other normal or dev dependency.
- NormalOrDevOrArtifactTarget(Option<CompileTarget>),
+ /// Normal or dev dependency.
+ #[default]
+ NormalOrDev,
  /// Build dependency or proc-macro.
  HostDep,
-}
-
-impl Default for FeaturesFor {
- fn default() -> Self {
- FeaturesFor::NormalOrDevOrArtifactTarget(None)
- }
+ /// Any dependency with both artifact and target specified.
+ ///
+ /// That is, `dep = { …, artifact = <crate-type>, target = <triple> }`
+ ArtifactDep(CompileTarget),
 }
 
 impl std::fmt::Display for FeaturesFor {
  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  match self {
  FeaturesFor::HostDep => f.write_str("host"),
- FeaturesFor::NormalOrDevOrArtifactTarget(Some(target)) => {
- f.write_str(&target.rustc_target())
- }
- FeaturesFor::NormalOrDevOrArtifactTarget(None) => Ok(()),
+ FeaturesFor::ArtifactDep(target) => f.write_str(&target.rustc_target()),
+ FeaturesFor::NormalOrDev => Ok(()),
  }
  }
 }
@@ -128,7 +127,7 @@ impl FeaturesFor {
  if for_host {
  FeaturesFor::HostDep
  } else {
- FeaturesFor::NormalOrDevOrArtifactTarget(None)
+ FeaturesFor::NormalOrDev
  }
  }
 
@@ -137,12 +136,12 @@ impl FeaturesFor {
  artifact_target: Option<CompileTarget>,
  ) -> FeaturesFor {
  match artifact_target {
- Some(target) => FeaturesFor::NormalOrDevOrArtifactTarget(Some(target)),
+ Some(target) => FeaturesFor::ArtifactDep(target),
  None => {
  if for_host {
  FeaturesFor::HostDep
  } else {
- FeaturesFor::NormalOrDevOrArtifactTarget(None)
+ FeaturesFor::NormalOrDev
  }
  }
  }
@@ -769,11 +768,11 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
  self.target_data
  .dep_platform_activated(dep, CompileKind::Host)
  }
- (_, FeaturesFor::NormalOrDevOrArtifactTarget(None)) => self
+ (_, FeaturesFor::NormalOrDev) => self
  .requested_targets
  .iter()
  .any(|kind| self.target_data.dep_platform_activated(dep, *kind)),
- (_, FeaturesFor::NormalOrDevOrArtifactTarget(Some(target))) => self
+ (_, FeaturesFor::ArtifactDep(target)) => self
  .target_data
  .dep_platform_activated(dep, CompileKind::Target(target)),
  }
@@ -832,17 +831,15 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
  artifact.is_lib(),
  artifact.target().map(|target| match target {
  ArtifactTarget::Force(target) => {
- vec![FeaturesFor::NormalOrDevOrArtifactTarget(Some(target))]
+ vec![FeaturesFor::ArtifactDep(target)]
  }
  ArtifactTarget::BuildDependencyAssumeTarget => self
  .requested_targets
  .iter()
  .filter_map(|kind| match kind {
  CompileKind::Host => None,
  CompileKind::Target(target) => {
- Some(FeaturesFor::NormalOrDevOrArtifactTarget(
- Some(*target),
- ))
+ Some(FeaturesFor::ArtifactDep(*target))
  }
  })
  .collect(),

src/cargo/ops/cargo_compile.rs

@@ -1424,7 +1424,7 @@ pub fn resolve_all_features(
  package_id: PackageId,
 ) -> HashSet<String> {
  let mut features: HashSet<String> = resolved_features
- .activated_features(package_id, FeaturesFor::NormalOrDevOrArtifactTarget(None))
+ .activated_features(package_id, FeaturesFor::NormalOrDev)
  .iter()
  .map(|s| s.to_string())
  .collect();

src/cargo/ops/tree/graph.rs

@@ -325,8 +325,8 @@ fn add_pkg(
  let node_features = resolved_features.activated_features(package_id, features_for);
  let node_kind = match features_for {
  FeaturesFor::HostDep => CompileKind::Host,
- FeaturesFor::NormalOrDevOrArtifactTarget(Some(target)) => CompileKind::Target(target),
- FeaturesFor::NormalOrDevOrArtifactTarget(None) => requested_kind,
+ FeaturesFor::ArtifactDep(target) => CompileKind::Target(target),
+ FeaturesFor::NormalOrDev => requested_kind,
  };
  let node = Node::Package {
  package_id,