Re-implement proc-macro feature decoupling.

Cargo.toml

@@ -22,7 +22,7 @@ path = "src/cargo/lib.rs"
 atty = "0.2"
 bytesize = "1.0"
 cargo-platform = { path = "crates/cargo-platform", version = "0.1.1" }
-crates-io = { path = "crates/crates-io", version = "0.32" }
+crates-io = { path = "crates/crates-io", version = "0.31" }
 crossbeam-utils = "0.7"
 crypto-hash = "0.3.1"
 curl = { version = "0.4.23", features = ["http2"] }

crates/cargo-test-support/src/registry.rs

@@ -420,7 +420,6 @@ impl Package {
             "cksum": cksum,
             "features": self.features,
             "yanked": self.yanked,
-            "pm": self.proc_macro,
         })
         .to_string();
 

crates/crates-io/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "crates-io"
-version = "0.32.0"
+version = "0.31.0"
 edition = "2018"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
 license = "MIT OR Apache-2.0"

crates/crates-io/lib.rs

@@ -55,7 +55,6 @@ pub struct NewCrate {
     pub repository: Option<String>,
     pub badges: BTreeMap<String, BTreeMap<String, String>>,
     pub links: Option<String>,
-    pub proc_macro: bool,
 }
 
 #[derive(Serialize)]

crates/resolver-tests/src/lib.rs

@@ -176,7 +176,6 @@ pub fn resolve_with_config_raw(
         &BTreeMap::<String, Vec<String>>::new(),
         None::<&String>,
         false,
-        false,
     )
     .unwrap();
     let opts = ResolveOpts::everything();
@@ -578,7 +577,6 @@ pub fn pkg_dep<T: ToPkgId>(name: T, dep: Vec<Dependency>) -> Summary {
         &BTreeMap::<String, Vec<String>>::new(),
         link,
         false,
-        false,
     )
     .unwrap()
 }
@@ -607,7 +605,6 @@ pub fn pkg_loc(name: &str, loc: &str) -> Summary {
         &BTreeMap::<String, Vec<String>>::new(),
         link,
         false,
-        false,
     )
     .unwrap()
 }
@@ -622,7 +619,6 @@ pub fn remove_dep(sum: &Summary, ind: usize) -> Summary {
         &BTreeMap::<String, Vec<String>>::new(),
         sum.links().map(|a| a.as_str()),
         sum.namespaced_features(),
-        sum.proc_macro(),
     )
     .unwrap()
 }

src/cargo/core/compiler/unit_dependencies.rs

@@ -19,7 +19,6 @@ use crate::core::compiler::unit_graph::{UnitDep, UnitGraph};
 use crate::core::compiler::Unit;
 use crate::core::compiler::{BuildContext, CompileKind, CompileMode};
 use crate::core::dependency::DepKind;
-use crate::core::package::Downloads;
 use crate::core::profiles::{Profile, UnitFor};
 use crate::core::resolver::features::{FeaturesFor, ResolvedFeatures};
 use crate::core::resolver::Resolve;
@@ -31,10 +30,7 @@ use std::collections::{HashMap, HashSet};
 /// Collection of stuff used while creating the `UnitGraph`.
 struct State<'a, 'cfg> {
     bcx: &'a BuildContext<'a, 'cfg>,
-    waiting_on_download: HashSet<PackageId>,
-    downloads: Downloads<'a, 'cfg>,
     unit_dependencies: UnitGraph<'a>,
-    package_cache: HashMap<PackageId, &'a Package>,
     usr_resolve: &'a Resolve,
     usr_features: &'a ResolvedFeatures,
     std_resolve: Option<&'a Resolve>,
@@ -58,10 +54,7 @@ pub fn build_unit_dependencies<'a, 'cfg>(
     };
     let mut state = State {
         bcx,
-        downloads: bcx.packages.enable_download()?,
-        waiting_on_download: HashSet::new(),
         unit_dependencies: HashMap::new(),
-        package_cache: HashMap::new(),
         usr_resolve: resolve,
         usr_features: features,
         std_resolve,
@@ -141,44 +134,32 @@ fn attach_std_deps<'a, 'cfg>(
 /// Compute all the dependencies of the given root units.
 /// The result is stored in state.unit_dependencies.
 fn deps_of_roots<'a, 'cfg>(roots: &[Unit<'a>], mut state: &mut State<'a, 'cfg>) -> CargoResult<()> {
-    // Loop because we are downloading while building the dependency graph.
-    // The partially-built unit graph is discarded through each pass of the
-    // loop because it is incomplete because not all required Packages have
-    // been downloaded.
-    loop {
-        for unit in roots.iter() {
-            state.get(unit.pkg.package_id())?;
-
-            // Dependencies of tests/benches should not have `panic` set.
-            // We check the global test mode to see if we are running in `cargo
-            // test` in which case we ensure all dependencies have `panic`
-            // cleared, and avoid building the lib thrice (once with `panic`, once
-            // without, once for `--test`). In particular, the lib included for
-            // Doc tests and examples are `Build` mode here.
-            let unit_for = if unit.mode.is_any_test() || state.bcx.build_config.test() {
-                UnitFor::new_test(state.bcx.config)
-            } else if unit.target.is_custom_build() {
-                // This normally doesn't happen, except `clean` aggressively
-                // generates all units.
-                UnitFor::new_host(false)
-            } else if unit.target.proc_macro() {
-                UnitFor::new_host(true)
-            } else if unit.target.for_host() {
-                // Plugin should never have panic set.
-                UnitFor::new_compiler()
-            } else {
-                UnitFor::new_normal()
-            };
-            deps_of(unit, &mut state, unit_for)?;
-        }
-
-        if !state.waiting_on_download.is_empty() {
-            state.finish_some_downloads()?;
-            state.unit_dependencies.clear();
+    for unit in roots.iter() {
+        state.get(unit.pkg.package_id());
+
+        // Dependencies of tests/benches should not have `panic` set.
+        // We check the global test mode to see if we are running in `cargo
+        // test` in which case we ensure all dependencies have `panic`
+        // cleared, and avoid building the lib thrice (once with `panic`, once
+        // without, once for `--test`). In particular, the lib included for
+        // Doc tests and examples are `Build` mode here.
+        let unit_for = if unit.mode.is_any_test() || state.bcx.build_config.test() {
+            UnitFor::new_test(state.bcx.config)
+        } else if unit.target.is_custom_build() {
+            // This normally doesn't happen, except `clean` aggressively
+            // generates all units.
+            UnitFor::new_host(false)
+        } else if unit.target.proc_macro() {
+            UnitFor::new_host(true)
+        } else if unit.target.for_host() {
+            // Plugin should never have panic set.
+            UnitFor::new_compiler()
         } else {
-            break;
-        }
+            UnitFor::new_normal()
+        };
+        deps_of(unit, &mut state, unit_for)?;
     }
+
     Ok(())
 }
 
@@ -269,10 +250,7 @@ fn compute_deps<'a, 'cfg>(
 
     let mut ret = Vec::new();
     for (id, _) in filtered_deps {
-        let pkg = match state.get(id)? {
-            Some(pkg) => pkg,
-            None => continue,
-        };
+        let pkg = state.get(id);
         let lib = match pkg.targets().iter().find(|t| t.is_lib()) {
             Some(t) => t,
             None => continue,
@@ -419,10 +397,7 @@ fn compute_deps_doc<'a, 'cfg>(
     // the documentation of the library being built.
     let mut ret = Vec::new();
     for (id, _deps) in deps {
-        let dep = match state.get(id)? {
-            Some(dep) => dep,
-            None => continue,
-        };
+        let dep = state.get(id);
         let lib = match dep.targets().iter().find(|t| t.is_lib()) {
             Some(lib) => lib,
             None => continue,
@@ -730,44 +705,10 @@ impl<'a, 'cfg> State<'a, 'cfg> {
         features.activated_features(pkg_id, features_for)
     }
 
-    fn get(&mut self, id: PackageId) -> CargoResult<Option<&'a Package>> {
-        if let Some(pkg) = self.package_cache.get(&id) {
-            return Ok(Some(pkg));
-        }
-        if !self.waiting_on_download.insert(id) {
-            return Ok(None);
-        }
-        if let Some(pkg) = self.downloads.start(id)? {
-            self.package_cache.insert(id, pkg);
-            self.waiting_on_download.remove(&id);
-            return Ok(Some(pkg));
-        }
-        Ok(None)
-    }
-
-    /// Completes at least one downloading, maybe waiting for more to complete.
-    ///
-    /// This function will block the current thread waiting for at least one
-    /// crate to finish downloading. The function may continue to download more
-    /// crates if it looks like there's a long enough queue of crates to keep
-    /// downloading. When only a handful of packages remain this function
-    /// returns, and it's hoped that by returning we'll be able to push more
-    /// packages to download into the queue.
-    fn finish_some_downloads(&mut self) -> CargoResult<()> {
-        assert!(self.downloads.remaining() > 0);
-        loop {
-            let pkg = self.downloads.wait()?;
-            self.waiting_on_download.remove(&pkg.package_id());
-            self.package_cache.insert(pkg.package_id(), pkg);
-
-            // Arbitrarily choose that 5 or more packages concurrently download
-            // is a good enough number to "fill the network pipe". If we have
-            // less than this let's recompute the whole unit dependency graph
-            // again and try to find some more packages to download.
-            if self.downloads.remaining() < 5 {
-                break;
-            }
-        }
-        Ok(())
+    fn get(&self, id: PackageId) -> &'a Package {
+        self.bcx
+            .packages
+            .get_one(id)
+            .unwrap_or_else(|_| panic!("expected {} to be downloaded", id))
     }
 }

src/cargo/core/package.rs

@@ -1,6 +1,6 @@
 use std::cell::{Cell, Ref, RefCell, RefMut};
 use std::cmp::Ordering;
-use std::collections::{HashMap, HashSet};
+use std::collections::{BTreeSet, HashMap, HashSet};
 use std::fmt;
 use std::hash;
 use std::mem;
@@ -17,7 +17,10 @@ use semver::Version;
 use serde::ser;
 use serde::Serialize;
 
+use crate::core::compiler::{CompileKind, RustcTargetData};
+use crate::core::dependency::DepKind;
 use crate::core::interning::InternedString;
+use crate::core::resolver::{HasDevUnits, Resolve};
 use crate::core::source::MaybePackage;
 use crate::core::{Dependency, Manifest, PackageId, SourceId, Target};
 use crate::core::{FeatureMap, SourceMap, Summary};
@@ -189,6 +192,10 @@ impl Package {
     pub fn publish(&self) -> &Option<Vec<String>> {
         self.manifest.publish()
     }
+    /// Returns `true` if this package is a proc-macro.
+    pub fn proc_macro(&self) -> bool {
+        self.targets().iter().any(|target| target.proc_macro())
+    }
 
     /// Returns `true` if the package uses a custom build script for any target.
     pub fn has_custom_build(&self) -> bool {
@@ -432,6 +439,9 @@ impl<'cfg> PackageSet<'cfg> {
     }
 
     pub fn get_one(&self, id: PackageId) -> CargoResult<&Package> {
+        if let Some(pkg) = self.packages.get(&id).and_then(|slot| slot.borrow()) {
+            return Ok(pkg);
+        }
         Ok(self.get_many(Some(id))?.remove(0))
     }
 
@@ -448,6 +458,75 @@ impl<'cfg> PackageSet<'cfg> {
         Ok(pkgs)
     }
 
+    /// Downloads any packages accessible from the give root ids.
+    pub fn download_accessible(
+        &self,
+        resolve: &Resolve,
+        root_ids: &[PackageId],
+        has_dev_units: HasDevUnits,
+        requested_kind: CompileKind,
+        target_data: &RustcTargetData,
+    ) -> CargoResult<()> {
+        fn collect_used_deps(
+            used: &mut BTreeSet<PackageId>,
+            resolve: &Resolve,
+            pkg_id: PackageId,
+            has_dev_units: HasDevUnits,
+            requested_kind: CompileKind,
+            target_data: &RustcTargetData,
+        ) -> CargoResult<()> {
+            if !used.insert(pkg_id) {
+                return Ok(());
+            }
+            let filtered_deps = resolve.deps(pkg_id).filter(|&(_id, deps)| {
+                deps.iter().any(|dep| {
+                    if dep.kind() == DepKind::Development && has_dev_units == HasDevUnits::No {
+                        return false;
+                    }
+                    // This is overly broad, since not all target-specific
+                    // dependencies are used both for target and host. To tighten this
+                    // up, this function would need to track "for_host" similar to how
+                    // unit dependencies handles it.
+                    if !target_data.dep_platform_activated(dep, requested_kind)
+                        && !target_data.dep_platform_activated(dep, CompileKind::Host)
+                    {
+                        return false;
+                    }
+                    true
+                })
+            });
+            for (dep_id, _deps) in filtered_deps {
+                collect_used_deps(
+                    used,
+                    resolve,
+                    dep_id,
+                    has_dev_units,
+                    requested_kind,
+                    target_data,
+                )?;
+            }
+            Ok(())
+        }
+
+        // This is sorted by PackageId to get consistent behavior and error
+        // messages for Cargo's testsuite. Perhaps there is a better ordering
+        // that optimizes download time?
+        let mut to_download = BTreeSet::new();
+
+        for id in root_ids {
+            collect_used_deps(
+                &mut to_download,
+                resolve,
+                *id,
+                has_dev_units,
+                requested_kind,
+                target_data,
+            )?;
+        }
+        self.get_many(to_download.into_iter())?;
+        Ok(())
+    }
+
     pub fn sources(&self) -> Ref<'_, SourceMap<'cfg>> {
         self.sources.borrow()
     }