Use -Z rustdoc-map instead of rewriting it

crates/metadata/lib.rs

@@ -229,7 +229,8 @@ impl Metadata {
     /// For example, the links may point somewhere different than they would on docs.rs.
     /// However, rustdoc will see exactly the same code as it would on docs.rs, even counting `cfg`s.
     pub fn cargo_args(&self, additional_args: &[String], rustdoc_args: &[String]) -> Vec<String> {
-        let mut cargo_args: Vec<String> = vec!["rustdoc".into(), "--lib".into()];
+        let mut cargo_args: Vec<String> =
+            vec!["rustdoc".into(), "--lib".into(), "-Zrustdoc-map".into()];
 
         if let Some(features) = &self.features {
             cargo_args.push("--features".into());
@@ -521,7 +522,12 @@ mod test_calculations {
     use super::*;
 
     fn default_cargo_args() -> Vec<String> {
-        vec!["rustdoc".into(), "--lib".into(), "--".into()]
+        vec![
+            "rustdoc".into(),
+            "--lib".into(),
+            "-Zrustdoc-map".into(),
+            "--".into(),
+        ]
     }
 
     #[test]
@@ -574,6 +580,7 @@ mod test_calculations {
         let expected_args = vec![
             "rustdoc".into(),
             "--lib".into(),
+            "-Zrustdoc-map".into(),
             "--features".into(),
             String::new(),
             "--".into(),
@@ -588,6 +595,7 @@ mod test_calculations {
         let expected_args = vec![
             String::from("rustdoc"),
             "--lib".into(),
+            "-Zrustdoc-map".into(),
             "--features".into(),
             "some_feature".into(),
             "--".into(),
@@ -602,6 +610,7 @@ mod test_calculations {
         let expected_args = vec![
             String::from("rustdoc"),
             "--lib".into(),
+            "-Zrustdoc-map".into(),
             "--features".into(),
             "feature1 feature2".into(),
             "--".into(),
@@ -623,6 +632,7 @@ mod test_calculations {
         let expected_args = vec![
             String::from("rustdoc"),
             "--lib".into(),
+            "-Zrustdoc-map".into(),
             "--".into(),
             "-Z".into(),
             "unstable-options".into(),
@@ -641,6 +651,7 @@ mod test_calculations {
         let expected_args = vec![
             String::from("rustdoc"),
             "--lib".into(),
+            "-Zrustdoc-map".into(),
             "-Z".into(),
             "unstable-options".into(),
             "--config".into(),

src/docbuilder/rustwide_builder.rs

@@ -518,16 +518,6 @@ impl RustwideBuilder {
 
         let mut rustdoc_flags = Vec::new();
 
-        for dep in &cargo_metadata.root_dependencies() {
-            rustdoc_flags.push("--extern-html-root-url".to_string());
-            rustdoc_flags.push(format!(
-                "{}=https://docs.rs/{}/{}",
-                dep.name.replace("-", "_"),
-                dep.name,
-                dep.version
-            ));
-        }
-
         rustdoc_flags.extend(vec![
             "--resource-suffix".to_string(),
             format!("-{}", parse_rustc_version(&self.rustc_version)?),
@@ -589,6 +579,12 @@ impl RustwideBuilder {
 
         // Add docs.rs specific arguments
         let mut cargo_args = Vec::new();
+        // Show the command line Rustdoc is invoked with
+        cargo_args.push("--verbose".into());
+        // We know that `metadata` unconditionally passes `-Z rustdoc-map`.
+        // Don't copy paste this, since that fact is not stable and may change in the future.
+        cargo_args.push("-Zunstable-options".into());
+        cargo_args.push(r#"--config=doc.extern-map.registries.crates-io="https://docs.rs""#.into());
         if let Some(cpu_limit) = self.config.build_cpu_limit {
             cargo_args.push(format!("-j{}", cpu_limit));
         }

src/utils/cargo_metadata.rs

@@ -1,13 +1,11 @@
 use crate::error::Result;
 use rustwide::{cmd::Command, Toolchain, Workspace};
 use serde::{Deserialize, Serialize};
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::path::Path;
 
 pub(crate) struct CargoMetadata {
-    packages: HashMap<String, Package>,
-    deps_graph: HashMap<String, HashSet<String>>,
-    root_id: String,
+    root: Package,
 }
 
 impl CargoMetadata {
@@ -31,34 +29,18 @@ impl CargoMetadata {
             ));
         };
 
-        // Convert from Vecs to HashMaps and HashSets to get more efficient lookups
+        let root = metadata.resolve.root;
         Ok(CargoMetadata {
-            packages: metadata
+            root: metadata
                 .packages
                 .into_iter()
-                .map(|pkg| (pkg.id.clone(), pkg))
-                .collect(),
-            deps_graph: metadata
-                .resolve
-                .nodes
-                .into_iter()
-                .map(|node| (node.id, node.deps.into_iter().map(|d| d.pkg).collect()))
-                .collect(),
-            root_id: metadata.resolve.root,
+                .find(|pkg| pkg.id == root)
+                .unwrap(),
         })
     }
 
-    pub(crate) fn root_dependencies(&self) -> Vec<&Package> {
-        let ids = &self.deps_graph[&self.root_id];
-        self.packages
-            .iter()
-            .filter(|(id, _pkg)| ids.contains(id.as_str()))
-            .map(|(_id, pkg)| pkg)
-            .collect()
-    }
-
     pub(crate) fn root(&self) -> &Package {
-        &self.packages[&self.root_id]
+        &self.root
     }
 }