Rewrite target filtering to filter the entire graph.

This also removes the special `host` target.

src/cargo/ops/cargo_output_metadata.rs

@@ -1,10 +1,9 @@
 use crate::core::compiler::{CompileKind, CompileTarget, TargetInfo};
 use crate::core::resolver::{Resolve, ResolveOpts};
-use crate::core::{Dependency, Package, PackageId, Workspace};
+use crate::core::{Package, PackageId, Workspace};
 use crate::ops::{self, Packages};
 use crate::util::CargoResult;
-use cargo_platform::Cfg;
-use serde::ser;
+
 use serde::Serialize;
 use std::collections::HashMap;
 use std::path::PathBuf;
@@ -35,53 +34,14 @@ pub fn output_metadata(ws: &Workspace<'_>, opt: &OutputMetadataOptions) -> Cargo
         let packages = ws.members().cloned().collect();
         (packages, None)
     } else {
-        let specs = Packages::All.to_package_id_specs(ws)?;
-        let opts = ResolveOpts::new(
+        let resolve_opts = ResolveOpts::new(
             /*dev_deps*/ true,
             &opt.features,
             opt.all_features,
             !opt.no_default_features,
         );
-        let ws_resolve = ops::resolve_ws_with_opts(ws, opts, &specs)?;
-        let mut package_map = HashMap::new();
-        for pkg in ws_resolve
-            .pkg_set
-            .get_many(ws_resolve.pkg_set.package_ids())?
-        {
-            package_map.insert(pkg.package_id(), pkg.clone());
-        }
-        let packages = package_map.values().map(|p| (*p).clone()).collect();
-        let rustc = ws.config().load_global_rustc(Some(ws))?;
-        let (target, cfg) = match &opt.filter_platform {
-            Some(platform) => {
-                if platform == "host" {
-                    let ti =
-                        TargetInfo::new(ws.config(), CompileKind::Host, &rustc, CompileKind::Host)?;
-                    (
-                        Some(rustc.host.as_str().to_string()),
-                        Some(ti.cfg().iter().cloned().collect()),
-                    )
-                } else {
-                    let kind = CompileKind::Target(CompileTarget::new(platform)?);
-                    let ti = TargetInfo::new(ws.config(), kind, &rustc, kind)?;
-                    (
-                        Some(platform.clone()),
-                        Some(ti.cfg().iter().cloned().collect()),
-                    )
-                }
-            }
-            None => (None, None),
-        };
-        let resolve = Some(MetadataResolve {
-            helper: ResolveHelper {
-                packages: package_map,
-                resolve: ws_resolve.targeted_resolve,
-                target,
-                cfg,
-            },
-            root: ws.current_opt().map(|pkg| pkg.package_id()),
-        });
-        (packages, resolve)
+        let (packages, resolve) = build_resolve_graph(ws, resolve_opts, &opt.filter_platform)?;
+        (packages, Some(resolve))
     };
 
     Ok(ExportInfo {
@@ -104,81 +64,123 @@ pub struct ExportInfo {
     workspace_root: PathBuf,
 }
 
-/// Newtype wrapper to provide a custom `Serialize` implementation.
-/// The one from lock file does not fit because it uses a non-standard
-/// format for `PackageId`s
 #[derive(Serialize)]
 struct MetadataResolve {
-    #[serde(rename = "nodes", serialize_with = "serialize_resolve")]
-    helper: ResolveHelper,
+    nodes: Vec<MetadataResolveNode>,
     root: Option<PackageId>,
 }
 
-struct ResolveHelper {
-    packages: HashMap<PackageId, Package>,
-    resolve: Resolve,
-    target: Option<String>,
-    cfg: Option<Vec<Cfg>>,
+#[derive(Serialize)]
+struct MetadataResolveNode {
+    id: PackageId,
+    dependencies: Vec<PackageId>,
+    deps: Vec<Dep>,
+    features: Vec<String>,
 }
 
-fn serialize_resolve<S>(helper: &ResolveHelper, s: S) -> Result<S::Ok, S::Error>
-where
-    S: ser::Serializer,
-{
-    let ResolveHelper {
-        packages,
-        resolve,
-        target,
-        cfg,
-    } = helper;
+#[derive(Serialize)]
+struct Dep {
+    name: String,
+    pkg: PackageId,
+}
 
-    #[derive(Serialize)]
-    struct Dep {
-        name: String,
-        pkg: PackageId,
+fn build_resolve_graph(
+    ws: &Workspace<'_>,
+    resolve_opts: ResolveOpts,
+    target: &Option<String>,
+) -> CargoResult<(Vec<Package>, MetadataResolve)> {
+    let target_info = match target {
+        Some(target) => {
+            let config = ws.config();
+            let ct = CompileTarget::new(target)?;
+            let short_name = ct.short_name().to_string();
+            let kind = CompileKind::Target(ct);
+            let rustc = config.load_global_rustc(Some(ws))?;
+            Some((short_name, TargetInfo::new(config, kind, &rustc, kind)?))
+        }
+        None => None,
+    };
+    // Resolve entire workspace.
+    let specs = Packages::All.to_package_id_specs(ws)?;
+    let ws_resolve = ops::resolve_ws_with_opts(ws, resolve_opts, &specs)?;
+    // Download all Packages. This is needed to serialize the information
+    // for every package. In theory this could honor target filtering,
+    // but that would be somewhat complex.
+    let mut package_map: HashMap<PackageId, Package> = ws_resolve
+        .pkg_set
+        .get_many(ws_resolve.pkg_set.package_ids())?
+        .into_iter()
+        .map(|pkg| (pkg.package_id(), pkg.clone()))
+        .collect();
+    // Start from the workspace roots, and recurse through filling out the
+    // map, filtering targets as necessary.
+    let mut node_map = HashMap::new();
+    for member_pkg in ws.members() {
+        build_resolve_graph_r(
+            &mut node_map,
+            member_pkg.package_id(),
+            &ws_resolve.targeted_resolve,
+            &package_map,
+            target_info.as_ref(),
+        );
     }
+    // Get a Vec of Packages.
+    let actual_packages = package_map
+        .drain()
+        .filter_map(|(pkg_id, pkg)| node_map.get(&pkg_id).map(|_| pkg))
+        .collect();
+    let mr = MetadataResolve {
+        nodes: node_map.drain().map(|(_pkg_id, node)| node).collect(),
+        root: ws.current_opt().map(|pkg| pkg.package_id()),
+    };
+    Ok((actual_packages, mr))
+}
 
-    #[derive(Serialize)]
-    struct Node<'a> {
-        id: PackageId,
-        dependencies: Vec<PackageId>,
-        deps: Vec<Dep>,
-        features: Vec<&'a str>,
+fn build_resolve_graph_r(
+    node_map: &mut HashMap<PackageId, MetadataResolveNode>,
+    pkg_id: PackageId,
+    resolve: &Resolve,
+    package_map: &HashMap<PackageId, Package>,
+    target: Option<&(String, TargetInfo)>,
+) {
+    if node_map.contains_key(&pkg_id) {
+        return;
     }
-
-    // A filter for removing platform dependencies.
-    let dep_filter = |(_pkg, deps): &(PackageId, &[Dependency])| match (target, cfg) {
-        (Some(target), Some(cfg)) => deps.iter().any(|dep| {
-            let platform = match dep.platform() {
-                Some(p) => p,
-                None => return true,
-            };
-            platform.matches(target, cfg)
-        }),
-        (None, None) => true,
-        _ => unreachable!(),
+    let features = resolve
+        .features_sorted(pkg_id)
+        .into_iter()
+        .map(|s| s.to_string())
+        .collect();
+    let deps: Vec<Dep> = resolve
+        .deps(pkg_id)
+        .filter(|(_dep_id, deps)| match target {
+            Some((short_name, info)) => deps.iter().any(|dep| {
+                let platform = match dep.platform() {
+                    Some(p) => p,
+                    None => return true,
+                };
+                platform.matches(short_name, info.cfg())
+            }),
+            None => true,
+        })
+        .filter_map(|(dep_id, _deps)| {
+            package_map
+                .get(&dep_id)
+                .and_then(|pkg| pkg.targets().iter().find(|t| t.is_lib()))
+                .and_then(|lib_target| resolve.extern_crate_name(pkg_id, dep_id, lib_target).ok())
+                .map(|name| Dep { name, pkg: dep_id })
+        })
+        .collect();
+    let dumb_deps: Vec<PackageId> = deps.iter().map(|dep| dep.pkg).collect();
+    let to_visit = dumb_deps.clone();
+    let node = MetadataResolveNode {
+        id: pkg_id,
+        dependencies: dumb_deps,
+        deps,
+        features,
     };
-
-    s.collect_seq(resolve.iter().map(|id| {
-        Node {
-            id,
-            dependencies: resolve
-                .deps(id)
-                .filter(dep_filter)
-                .map(|(pkg, _deps)| pkg)
-                .collect(),
-            deps: resolve
-                .deps(id)
-                .filter(dep_filter)
-                .filter_map(|(pkg, _deps)| {
-                    packages
-                        .get(&pkg)
-                        .and_then(|pkg| pkg.targets().iter().find(|t| t.is_lib()))
-                        .and_then(|lib_target| resolve.extern_crate_name(id, pkg, lib_target).ok())
-                        .map(|name| Dep { name, pkg })
-                })
-                .collect(),
-            features: resolve.features_sorted(id),
-        }
-    }))
+    node_map.insert(pkg_id, node);
+    for dep_id in to_visit {
+        build_resolve_graph_r(node_map, dep_id, resolve, package_map, target);
+    }
 }