Auto merge of #8074 - ehuss:package-features2, r=alexcrichton

Extend -Zpackage-features with more capabilities.

This is a proposal to extend `-Zpackage-features` with new abilities to change how features are selected on the command-line.  See `unstable.md` for documentation on what it does.

I've contemplated a variety of ways we could transition this to stable. I tried a few experiments trying to make a "transition with warnings" mode, but I'm just too concerned about breaking backwards compatibility.  The current way is just fundamentally different from the new way, and I think it would be a bumpy ride to try to push it.

The stabilization story is that the parts of this that add new functionality (feature flags in virtual worskpaces, and `member/feat` syntax) can be stabilized at any time.  The change for `cargo build -p member --features feat` in a different member's directory can maybe be part of `-Zfeatures` stabilization, which will need to be opt-in.  I've been trying to come up with some transition plan, and I can't think of a way without making it opt-in, and making it part of `-Zfeatures` is an opportunity to simplify things.  One concern is that this might be confusing (`--features` flag could behave differently in different workspaces, and documenting the differences), but that seems hard to avoid.

Closes #6195
Closes #4753
Closes #5015
Closes #4106
Closes #5362

src/cargo/core/workspace.rs

@@ -1,7 +1,8 @@
 use std::cell::RefCell;
 use std::collections::hash_map::{Entry, HashMap};
-use std::collections::{BTreeMap, HashSet};
+use std::collections::{BTreeMap, BTreeSet, HashSet};
 use std::path::{Path, PathBuf};
+use std::rc::Rc;
 use std::slice;
 
 use glob::glob;
@@ -11,7 +12,7 @@ use url::Url;
 use crate::core::features::Features;
 use crate::core::registry::PackageRegistry;
 use crate::core::resolver::features::RequestedFeatures;
-use crate::core::{Dependency, PackageId, PackageIdSpec};
+use crate::core::{Dependency, InternedString, PackageId, PackageIdSpec};
 use crate::core::{EitherManifest, Package, SourceId, VirtualManifest};
 use crate::ops;
 use crate::sources::PathSource;
@@ -878,59 +879,143 @@ impl<'cfg> Workspace<'cfg> {
  .collect());
  }
  if self.config().cli_unstable().package_features {
- if specs.len() > 1 && !requested_features.features.is_empty() {
- anyhow::bail!("cannot specify features for more than one package");
+ self.members_with_features_pf(specs, requested_features)
+ } else {
+ self.members_with_features_stable(specs, requested_features)
+ }
+ }
+
+ /// New command-line feature selection with -Zpackage-features.
+ fn members_with_features_pf(
+ &self,
+ specs: &[PackageIdSpec],
+ requested_features: &RequestedFeatures,
+ ) -> CargoResult<Vec<(&Package, RequestedFeatures)>> {
+ // Keep track of which features matched *any* member, to produce an error
+ // if any of them did not match anywhere.
+ let mut found: BTreeSet<InternedString> = BTreeSet::new();
+
+ // Returns the requested features for the given member.
+ // This filters out any named features that the member does not have.
+ let mut matching_features = |member: &Package| -> RequestedFeatures {
+ if requested_features.features.is_empty() || requested_features.all_features {
+ return requested_features.clone();
+ }
+ // Only include features this member defines.
+ let summary = member.summary();
+ let member_features = summary.features();
+ let mut features = BTreeSet::new();
+
+ // Checks if a member contains the given feature.
+ let contains = |feature: InternedString| -> bool {
+ member_features.contains_key(&feature)
+ || summary
+ .dependencies()
+ .iter()
+ .any(|dep| dep.is_optional() && dep.name_in_toml() == feature)
+ };
+
+ for feature in requested_features.features.iter() {
+ let mut split = feature.splitn(2, '/');
+ let split = (split.next().unwrap(), split.next());
+ if let (pkg, Some(pkg_feature)) = split {
+ let pkg = InternedString::new(pkg);
+ let pkg_feature = InternedString::new(pkg_feature);
+ if summary
+ .dependencies()
+ .iter()
+ .any(|dep| dep.name_in_toml() == pkg)
+ {
+ // pkg/feat for a dependency.
+ // Will rely on the dependency resolver to validate `feat`.
+ features.insert(*feature);
+ found.insert(*feature);
+ } else if pkg == member.name() && contains(pkg_feature) {
+ // member/feat where "feat" is a feature in member.
+ features.insert(pkg_feature);
+ found.insert(*feature);
+ }
+ } else if contains(*feature) {
+ // feature exists in this member.
+ features.insert(*feature);
+ found.insert(*feature);
+ }
+ }
+ RequestedFeatures {
+ features: Rc::new(features),
+ all_features: false,
+ uses_default_features: requested_features.uses_default_features,
+ }
+ };
+
+ let members: Vec<(&Package, RequestedFeatures)> = self
+ .members()
+ .filter(|m| specs.iter().any(|spec| spec.matches(m.package_id())))
+ .map(|m| (m, matching_features(m)))
+ .collect();
+ if members.is_empty() {
+ // `cargo build -p foo`, where `foo` is not a member.
+ // Do not allow any command-line flags (defaults only).
+ if !(requested_features.features.is_empty()
+ && !requested_features.all_features
+ && requested_features.uses_default_features)
+ {
+ anyhow::bail!("cannot specify features for packages outside of workspace");
  }
- let members: Vec<(&Package, RequestedFeatures)> = self
+ // Add all members from the workspace so we can ensure `-p nonmember`
+ // is in the resolve graph.
+ return Ok(self
  .members()
- .filter(|m| specs.iter().any(|spec| spec.matches(m.package_id())))
- .map(|m| (m, requested_features.clone()))
+ .map(|m| (m, RequestedFeatures::new_all(false)))
+ .collect());
+ }
+ if *requested_features.features != found {
+ let missing: Vec<_> = requested_features
+ .features
+ .difference(&found)
+ .copied()
  .collect();
- if members.is_empty() {
- // `cargo build -p foo`, where `foo` is not a member.
- // Do not allow any command-line flags (defaults only).
- if !(requested_features.features.is_empty()
- && !requested_features.all_features
- && requested_features.uses_default_features)
- {
- anyhow::bail!("cannot specify features for packages outside of workspace");
+ // TODO: typo suggestions would be good here.
+ anyhow::bail!(
+ "none of the selected packages contains these features: {}",
+ missing.join(", ")
+ );
+ }
+ Ok(members)
+ }
+
+ /// This is the current "stable" behavior for command-line feature selection.
+ fn members_with_features_stable(
+ &self,
+ specs: &[PackageIdSpec],
+ requested_features: &RequestedFeatures,
+ ) -> CargoResult<Vec<(&Package, RequestedFeatures)>> {
+ let ms = self.members().filter_map(|member| {
+ let member_id = member.package_id();
+ match self.current_opt() {
+ // The features passed on the command-line only apply to
+ // the "current" package (determined by the cwd).
+ Some(current) if member_id == current.package_id() => {
+ Some((member, requested_features.clone()))
  }
- // Add all members from the workspace so we can ensure `-p nonmember`
- // is in the resolve graph.
- return Ok(self
- .members()
- .map(|m| (m, RequestedFeatures::new_all(false)))
- .collect());
- }
- Ok(members)
- } else {
- let ms = self.members().filter_map(|member| {
- let member_id = member.package_id();
- match self.current_opt() {
- // The features passed on the command-line only apply to
- // the "current" package (determined by the cwd).
- Some(current) if member_id == current.package_id() => {
- Some((member, requested_features.clone()))
- }
- _ => {
- // Ignore members that are not enabled on the command-line.
- if specs.iter().any(|spec| spec.matches(member_id)) {
- // -p for a workspace member that is not the
- // "current" one, don't use the local
- // `--features`, only allow `--all-features`.
- Some((
- member,
- RequestedFeatures::new_all(requested_features.all_features),
- ))
- } else {
- // This member was not requested on the command-line, skip.
- None
- }
+ _ => {
+ // Ignore members that are not enabled on the command-line.
+ if specs.iter().any(|spec| spec.matches(member_id)) {
+ // -p for a workspace member that is not the
+ // "current" one, don't use the local
+ // `--features`, only allow `--all-features`.
+ Some((
+ member,
+ RequestedFeatures::new_all(requested_features.all_features),
+ ))
+ } else {
+ // This member was not requested on the command-line, skip.
+ None
  }
  }
- });
-  Ok(ms.collect())
- }
+ }
+ });
+ Ok(ms.collect())
  }
 }
 

src/cargo/ops/cargo_clean.rs

@@ -62,7 +62,14 @@ pub fn clean(ws: &Workspace<'_>, opts: &CleanOptions<'_>) -> CargoResult<()> {
  let mut build_config = BuildConfig::new(config, Some(1), &opts.target, CompileMode::Build)?;
  build_config.requested_profile = opts.requested_profile;
  let target_data = RustcTargetData::new(ws, build_config.requested_kind)?;
- let resolve_opts = ResolveOpts::everything();
+ // Resolve for default features. In the future, `cargo clean` should be rewritten
+ // so that it doesn't need to guess filename hashes.
+ let resolve_opts = ResolveOpts::new(
+ /*dev_deps*/ true,
+ &[],
+ /*all features*/ false,
+ /*default*/ true,
+ );
  let specs = opts
  .spec
  .iter()

src/doc/src/reference/unstable.md

@@ -474,7 +474,7 @@ cargo +nightly -Zunstable-options -Zconfig-include --config somefile.toml build
 
 CLI paths are relative to the current working directory.
 
-## Features
+### Features
 * Tracking Issues:
  * [itarget #7914](https:/rust-lang/cargo/issues/7914)
  * [build_dep #7915](https:/rust-lang/cargo/issues/7915)
@@ -549,6 +549,31 @@ The available options are:
 * `compare` — This option compares the resolved features to the old resolver,
  and will print any differences.
 
+### package-features
+* Tracking Issue: [#5364](https:/rust-lang/cargo/issues/5364)
+
+The `-Zpackage-features` flag changes the way features can be passed on the
+command-line for a workspace. The normal behavior can be confusing, as the
+features passed are always enabled on the package in the current directory,
+even if that package is not selected with a `-p` flag. Feature flags also do
+not work in the root of a virtual workspace. `-Zpackage-features` tries to
+make feature flags behave in a more intuitive manner.
+
+* `cargo build -p other_member --features …` — This now only enables the given
+ features as defined in `other_member` (ignores whatever is in the current
+ directory).
+* `cargo build -p a -p b --features …` — This now enables the given features
+ on both `a` and `b`. Not all packages need to define every feature, it only
+ enables matching features. It is still an error if none of the packages
+ define a given feature.
+* `--features` and `--no-default-features` are now allowed in the root of a
+ virtual workspace.
+* `member_name/feature_name` syntax may now be used on the command-line to
+ enable features for a specific member.
+
+The ability to set features for non-workspace members is no longer allowed, as
+the resolver fundamentally does not support that ability.
+
 ### crate-versions
 * Tracking Issue: [#7907](https:/rust-lang/cargo/issues/7907)
 

tests/testsuite/features.rs

@@ -1358,80 +1358,6 @@ fn many_cli_features_comma_and_space_delimited() {
  .run();
 }
 
-#[cargo_test]
-fn combining_features_and_package() {
- Package::new("dep", "1.0.0").publish();
-
- let p = project()
- .file(
- "Cargo.toml",
- r#"
- [project]
- name = "foo"
- version = "0.0.1"
- authors = []
-
- [workspace]
- members = ["bar"]
-
- [dependencies]
- dep = "1"
- "#,
- )
- .file("src/lib.rs", "")
- .file(
- "bar/Cargo.toml",
- r#"
- [package]
- name = "bar"
- version = "0.0.1"
- authors = []
- [features]
- main = []
- "#,
- )
- .file(
- "bar/src/main.rs",
- r#"
- #[cfg(feature = "main")]
- fn main() {}
- "#,
- )
- .build();
-
- p.cargo("build -Z package-features --workspace --features main")
- .masquerade_as_nightly_cargo()
- .with_status(101)
- .with_stderr_contains("[ERROR] cannot specify features for more than one package")
- .run();
-
- p.cargo("build -Z package-features --package dep --features main")
- .masquerade_as_nightly_cargo()
- .with_status(101)
- .with_stderr_contains("[ERROR] cannot specify features for packages outside of workspace")
- .run();
- p.cargo("build -Z package-features --package dep --all-features")
- .masquerade_as_nightly_cargo()
- .with_status(101)
- .with_stderr_contains("[ERROR] cannot specify features for packages outside of workspace")
- .run();
- p.cargo("build -Z package-features --package dep --no-default-features")
- .masquerade_as_nightly_cargo()
- .with_status(101)
- .with_stderr_contains("[ERROR] cannot specify features for packages outside of workspace")
- .run();
-
- p.cargo("build -Z package-features --workspace --all-features")
- .masquerade_as_nightly_cargo()
- .run();
- p.cargo("run -Z package-features --package bar --features main")
- .masquerade_as_nightly_cargo()
- .run();
- p.cargo("build -Z package-features --package dep")
- .masquerade_as_nightly_cargo()
- .run();
-}
-
 #[cargo_test]
 fn namespaced_invalid_feature() {
  let p = project()

tests/testsuite/main.rs

@@ -73,6 +73,7 @@ mod offline;
 mod out_dir;
 mod owner;
 mod package;
+mod package_features;
 mod patch;
 mod path;
 mod paths;