Auto merge of #51448 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 13 pull requests

Successful merges:

 - #50143 (Add deprecation lint for duplicated `macro_export`s)
 - #51099 (Fix Issue 38777)
 - #51276 (Dedup auto traits in trait objects.)
 - #51298 (Stabilize unit tests with non-`()` return type)
 - #51360 (Suggest parentheses when a struct literal needs them)
 - #51391 (Use spans pointing at the inside of a rustdoc attribute)
 - #51394 (Use scope tree depths to speed up `nearest_common_ancestor`.)
 - #51396 (Make the size of Option<NonZero*> a documented guarantee.)
 - #51401 (Warn on `repr` without hints)
 - #51412 (Avoid useless Vec clones in pending_obligations().)
 - #51427 (compiletest: autoremove duplicate .nll.* files (#51204))
 - #51436 (Do not require stage 2 compiler for rustdoc)
 - #51437 (rustbuild: generate full list of dependencies for metadata)

Failed merges:

Author: bors

src/bootstrap/builder.rs

@@ -800,10 +800,7 @@ impl<'a> Builder<'a> {
             cargo.env("RUSTC_ERROR_FORMAT", error_format);
         }
         if cmd != "build" && cmd != "check" && want_rustdoc {
-            cargo.env(
-                "RUSTDOC_LIBDIR",
-                self.rustc_libdir(self.compiler(2, self.config.build)),
-            );
+            cargo.env("RUSTDOC_LIBDIR", self.sysroot_libdir(compiler, self.config.build));
         }
 
         if mode.is_tool() {

src/bootstrap/lib.rs

@@ -280,7 +280,8 @@ pub struct Build {
 struct Crate {
     name: Interned<String>,
     version: String,
-    deps: Vec<Interned<String>>,
+    deps: HashSet<Interned<String>>,
+    id: String,
     path: PathBuf,
     doc_step: String,
     build_step: String,