feat(unstable): add -Zrustdoc-depinfo flag

Author: weihanglo

src/cargo/core/features.rs

@@ -790,6 +790,7 @@ unstable_cli_options!(
     public_dependency: bool = ("Respect a dependency's `public` field in Cargo.toml to control public/private dependencies"),
     publish_timeout: bool = ("Enable the `publish.timeout` key in .cargo/config.toml file"),
     root_dir: Option<PathBuf> = ("Set the root directory relative to which paths are printed (defaults to workspace root)"),
+    rustdoc_depinfo: bool = ("Use dep-info files in rustdoc rebuild detection"),
     rustdoc_map: bool = ("Allow passing external documentation mappings to rustdoc"),
     rustdoc_scrape_examples: bool = ("Allows Rustdoc to scrape code examples from reverse-dependencies"),
     sbom: bool = ("Enable the `sbom` option in build config in .cargo/config.toml file"),
@@ -1303,6 +1304,7 @@ impl CliUnstable {
             "trim-paths" => self.trim_paths = parse_empty(k, v)?,
             "publish-timeout" => self.publish_timeout = parse_empty(k, v)?,
             "root-dir" => self.root_dir = v.map(|v| v.into()),
+            "rustdoc-depinfo" => self.rustdoc_depinfo = parse_empty(k, v)?,
             "rustdoc-map" => self.rustdoc_map = parse_empty(k, v)?,
             "rustdoc-scrape-examples" => self.rustdoc_scrape_examples = parse_empty(k, v)?,
             "sbom" => self.sbom = parse_empty(k, v)?,

tests/testsuite/cargo/z_help/stdout.term.svg

@@ -2897,3 +2897,20 @@ Caused by:
         .with_status(101)
         .run();
 }
+
+#[cargo_test(nightly, reason = "`rustdoc --emit` is unstable")]
+fn rustdoc_depinfo_gated() {
+    let p = project()
+        .file("Cargo.toml", &basic_lib_manifest("foo"))
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("doc -Zrustdoc-depinfo")
+        .with_status(101)
+        .with_stderr_data(str![[r#"
+[ERROR] the `-Z` flag is only accepted on the nightly channel of Cargo, but this is the `stable` channel
+See https://doc.rust-lang.org/book/appendix-07-nightly-rust.html for more information about Rust release channels.
+
+"#]])
+        .run();
+}