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Auto merge of #9574 - ehuss:weak-namespaced, r=alexcrichton
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Unify weak and namespaced features.

This unifies weak and namespaced features in order to simplify the syntax and semantics.  Previously there were four different ways to specify the feature of a dependency:

* `package-name/feature-name` — Enables feature `package-name` on self and enables `feature-name` on the dependency. (Today's behavior.)
* `package-name?/feature-name` — Only enables `feature-name` on the given package if it that package is enabled and will also activates a feature named `package-name` (which must be defined implicitly or explicitly).
* `dep:package-name/feature-name` — Enables dependency `package-name`, and enables `feature-name` on that dependency. This does NOT enable a feature named "package-name".
* `dep:package-name?/feature-name` — Only enables `feature-name` on the given package if it that package is enabled.  This does NOT enable a feature named "package-name".

This changes it so there are only two:

* `package-name/feature-name` — Today's behavior.
* `package-name?/feature-name` — Only enables `feature-name` on the given package if it that package is enabled.  This does NOT enable a feature named "package-name" (the same behavior as `dep:package-name?/feature-name` above).

This is a fairly subtle change, and in most cases probably won't be noticed.  However, it simplifies things which helps with writing documentation and explaining how it works.
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bors committed Jun 22, 2021
2 parents 32238b4 + 9034e48 commit a2589dd
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Showing 8 changed files with 74 additions and 205 deletions.
9 changes: 4 additions & 5 deletions src/cargo/core/resolver/dep_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -405,12 +405,12 @@ impl Requirements<'_> {
&mut self,
package: InternedString,
feat: InternedString,
dep_prefix: bool,
weak: bool,
) -> Result<(), RequirementError> {
// If `package` is indeed an optional dependency then we activate the
// feature named `package`, but otherwise if `package` is a required
// dependency then there's no feature associated with it.
if !dep_prefix
if !weak
&& self
.summary
.dependencies()
Expand Down Expand Up @@ -456,12 +456,11 @@ impl Requirements<'_> {
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix,
// Weak features are always activated in the dependency
// resolver. They will be narrowed inside the new feature
// resolver.
weak: _,
} => self.require_dep_feature(*dep_name, *dep_feature, *dep_prefix)?,
weak,
} => self.require_dep_feature(*dep_name, *dep_feature, *weak)?,
};
Ok(())
}
Expand Down
35 changes: 9 additions & 26 deletions src/cargo/core/resolver/features.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -244,10 +244,7 @@ impl CliFeatures {
match feature {
// Maybe call validate_feature_name here once it is an error?
FeatureValue::Feature(_) => {}
FeatureValue::Dep { .. }
| FeatureValue::DepFeature {
dep_prefix: true, ..
} => {
FeatureValue::Dep { .. } => {
bail!(
"feature `{}` is not allowed to use explicit `dep:` syntax",
feature
Expand Down Expand Up @@ -441,10 +438,8 @@ pub struct FeatureResolver<'a, 'cfg> {
///
/// The key is the `(package, for_host, dep_name)` of the package whose
/// dependency will trigger the addition of new features. The value is the
/// set of `(feature, dep_prefix)` features to activate (`dep_prefix` is a
/// bool that indicates if `dep:` prefix was used).
deferred_weak_dependencies:
HashMap<(PackageId, bool, InternedString), HashSet<(InternedString, bool)>>,
/// set of features to activate.
deferred_weak_dependencies: HashMap<(PackageId, bool, InternedString), HashSet<InternedString>>,
}

impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
Expand Down Expand Up @@ -591,17 +586,9 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix,
weak,
} => {
self.activate_dep_feature(
pkg_id,
for_host,
*dep_name,
*dep_feature,
*dep_prefix,
*weak,
)?;
self.activate_dep_feature(pkg_id, for_host, *dep_name, *dep_feature, *weak)?;
}
}
Ok(())
Expand Down Expand Up @@ -675,17 +662,14 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
continue;
}
if let Some(to_enable) = &to_enable {
for (dep_feature, dep_prefix) in to_enable {
for dep_feature in to_enable {
log::trace!(
"activate deferred {} {} -> {}/{}",
pkg_id.name(),
for_host,
dep_name,
dep_feature
);
if !dep_prefix {
self.activate_rec(pkg_id, for_host, dep_name)?;
}
let fv = FeatureValue::new(*dep_feature);
self.activate_fv(dep_pkg_id, dep_for_host, &fv)?;
}
Expand All @@ -704,7 +688,6 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
for_host: bool,
dep_name: InternedString,
dep_feature: InternedString,
dep_prefix: bool,
weak: bool,
) -> CargoResult<()> {
for (dep_pkg_id, deps) in self.deps(pkg_id, for_host) {
Expand Down Expand Up @@ -733,16 +716,16 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
self.deferred_weak_dependencies
.entry((pkg_id, for_host, dep_name))
.or_default()
.insert((dep_feature, dep_prefix));
.insert(dep_feature);
continue;
}

// Activate the dependency on self.
let fv = FeatureValue::Dep { dep_name };
self.activate_fv(pkg_id, for_host, &fv)?;
if !dep_prefix {
// To retain compatibility with old behavior,
// this also enables a feature of the same
if !weak {
// The old behavior before weak dependencies were
// added is to also enables a feature of the same
// name.
self.activate_rec(pkg_id, for_host, dep_name)?;
}
Expand Down
29 changes: 3 additions & 26 deletions src/cargo/core/summary.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -218,12 +218,7 @@ fn build_feature_map(
.values()
.flatten()
.filter_map(|fv| match fv {
Dep { dep_name }
| DepFeature {
dep_name,
dep_prefix: true,
..
} => Some(*dep_name),
Dep { dep_name } => Some(*dep_name),
_ => None,
})
.collect();
Expand Down Expand Up @@ -391,9 +386,6 @@ pub enum FeatureValue {
DepFeature {
dep_name: InternedString,
dep_feature: InternedString,
/// If this is true, then the feature used the `dep:` prefix, which
/// prevents enabling the feature named `dep_name`.
dep_prefix: bool,
/// If `true`, indicates the `?` syntax is used, which means this will
/// not automatically enable the dependency unless the dependency is
/// activated through some other means.
Expand All @@ -407,11 +399,6 @@ impl FeatureValue {
Some(pos) => {
let (dep, dep_feat) = feature.split_at(pos);
let dep_feat = &dep_feat[1..];
let (dep, dep_prefix) = if let Some(dep) = dep.strip_prefix("dep:") {
(dep, true)
} else {
(dep, false)
};
let (dep, weak) = if let Some(dep) = dep.strip_suffix('?') {
(dep, true)
} else {
Expand All @@ -420,7 +407,6 @@ impl FeatureValue {
FeatureValue::DepFeature {
dep_name: InternedString::new(dep),
dep_feature: InternedString::new(dep_feat),
dep_prefix,
weak,
}
}
Expand All @@ -438,14 +424,7 @@ impl FeatureValue {

/// Returns `true` if this feature explicitly used `dep:` syntax.
pub fn has_dep_prefix(&self) -> bool {
matches!(
self,
FeatureValue::Dep { .. }
| FeatureValue::DepFeature {
dep_prefix: true,
..
}
)
matches!(self, FeatureValue::Dep { .. })
}
}

Expand All @@ -458,12 +437,10 @@ impl fmt::Display for FeatureValue {
DepFeature {
dep_name,
dep_feature,
dep_prefix,
weak,
} => {
let dep_prefix = if *dep_prefix { "dep:" } else { "" };
let weak = if *weak { "?" } else { "" };
write!(f, "{}{}{}/{}", dep_prefix, dep_name, weak, dep_feature)
write!(f, "{}{}/{}", dep_name, weak, dep_feature)
}
}
}
Expand Down
18 changes: 3 additions & 15 deletions src/cargo/core/workspace.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1163,14 +1163,10 @@ impl<'cfg> Workspace<'cfg> {
}
}
// This should be enforced by CliFeatures.
FeatureValue::Dep { .. }
| FeatureValue::DepFeature {
dep_prefix: true, ..
} => panic!("unexpected dep: syntax {}", feature),
FeatureValue::Dep { .. } => panic!("unexpected dep: syntax {}", feature),
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix: _,
weak: _,
} => {
if dependencies.contains_key(dep_name) {
Expand Down Expand Up @@ -1283,14 +1279,10 @@ impl<'cfg> Workspace<'cfg> {
.map(|s| s.to_string())
.collect::<Vec<_>>()
}
FeatureValue::Dep { .. }
| FeatureValue::DepFeature {
dep_prefix: true, ..
} => panic!("unexpected dep: syntax {}", feature),
FeatureValue::Dep { .. } => panic!("unexpected dep: syntax {}", feature),
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix: _,
weak: _,
} => {
// Finds set of `pkg/feat` that are very similar to current `pkg/feat`.
Expand Down Expand Up @@ -1446,14 +1438,10 @@ impl<'cfg> Workspace<'cfg> {
cwd_features.insert(feature.clone());
}
// This should be enforced by CliFeatures.
FeatureValue::Dep { .. }
| FeatureValue::DepFeature {
dep_prefix: true, ..
} => panic!("unexpected dep: syntax {}", feature),
FeatureValue::Dep { .. } => panic!("unexpected dep: syntax {}", feature),
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix: _,
weak: _,
} => {
// I think weak can be ignored here.
Expand Down
6 changes: 1 addition & 5 deletions src/cargo/ops/cargo_compile.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1225,10 +1225,7 @@ fn validate_required_features(
))?;
}
}
FeatureValue::Dep { .. }
| FeatureValue::DepFeature {
dep_prefix: true, ..
} => {
FeatureValue::Dep { .. } => {
anyhow::bail!(
"invalid feature `{}` in required-features of target `{}`: \
`dep:` prefixed feature values are not allowed in required-features",
Expand All @@ -1248,7 +1245,6 @@ fn validate_required_features(
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix: false,
weak: false,
} => {
match resolve
Expand Down
15 changes: 7 additions & 8 deletions src/cargo/ops/tree/graph.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -488,7 +488,6 @@ fn add_cli_features(
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix: _,
weak,
} => {
let dep_connections = match graph.dep_name_map[&package_index].get(&dep_name) {
Expand Down Expand Up @@ -596,12 +595,12 @@ fn add_feature_rec(
FeatureValue::DepFeature {
dep_name,
dep_feature,
dep_prefix,
// `weak` is ignored, because it will be skipped if the
// corresponding dependency is not found in the map, which
// means it wasn't activated. Skipping is handled by
// `is_dep_activated` when the graph was built.
weak: _,
// Note: `weak` is mostly handled when the graph is built in
// `is_dep_activated` which is responsible for skipping
// unactivated weak dependencies. Here it is only used to
// determine if the feature of the dependency name is
// activated on self.
weak,
} => {
let dep_indexes = match graph.dep_name_map[&package_index].get(dep_name) {
Some(indexes) => indexes.clone(),
Expand All @@ -619,7 +618,7 @@ fn add_feature_rec(
};
for (dep_index, is_optional) in dep_indexes {
let dep_pkg_id = graph.package_id_for_index(dep_index);
if is_optional && !dep_prefix {
if is_optional && !weak {
// Activate the optional dep on self.
add_feature(
graph,
Expand Down
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