Revert "Don't load all extern crates unconditionally"

(cherry picked from commit 5f0c54d)

src/librustdoc/core.rs

@@ -1,12 +1,12 @@
-use rustc_ast as ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::{self, Lrc};
 use rustc_driver::abort_on_err;
 use rustc_errors::emitter::{Emitter, EmitterWriter};
 use rustc_errors::json::JsonEmitter;
 use rustc_feature::UnstableFeatures;
+use rustc_hir::def::Namespace::TypeNS;
 use rustc_hir::def::Res;
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_INDEX};
 use rustc_hir::HirId;
 use rustc_hir::{
     intravisit::{self, NestedVisitorMap, Visitor},
@@ -23,7 +23,7 @@ use rustc_session::DiagnosticOutput;
 use rustc_session::Session;
 use rustc_span::source_map;
 use rustc_span::symbol::sym;
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 
 use std::cell::RefCell;
 use std::mem;
@@ -300,17 +300,42 @@ crate fn create_config(
 }
 
 crate fn create_resolver<'a>(
+    externs: config::Externs,
     queries: &Queries<'a>,
     sess: &Session,
 ) -> Rc<RefCell<interface::BoxedResolver>> {
-    let parts = abort_on_err(queries.expansion(), sess).peek();
-    let (krate, resolver, _) = &*parts;
-    let resolver = resolver.borrow().clone();
-
-    let mut loader = crate::passes::collect_intra_doc_links::IntraLinkCrateLoader::new(resolver);
-    ast::visit::walk_crate(&mut loader, krate);
+    let extern_names: Vec<String> = externs
+        .iter()
+        .filter(|(_, entry)| entry.add_prelude)
+        .map(|(name, _)| name)
+        .cloned()
+        .collect();
+
+    let (_, resolver, _) = &*abort_on_err(queries.expansion(), sess).peek();
+    let resolver = resolver.borrow();
+
+    // Before we actually clone it, let's force all the extern'd crates to
+    // actually be loaded, just in case they're only referred to inside
+    // intra-doc links
+    resolver.borrow_mut().access(|resolver| {
+        sess.time("load_extern_crates", || {
+            for extern_name in &extern_names {
+                debug!("loading extern crate {}", extern_name);
+                if let Err(()) = resolver
+                    .resolve_str_path_error(
+                        DUMMY_SP,
+                        extern_name,
+                        TypeNS,
+                        LocalDefId { local_def_index: CRATE_DEF_INDEX }.to_def_id(),
+                  ) {
+                    warn!("unable to resolve external crate {} (do you have an unused `--extern` crate?)", extern_name)
+                  }
+            }
+        });
+    });
 
-    loader.resolver
+    // Now we're good to clone the resolver because everything should be loaded
+    resolver.clone()
 }
 
 crate fn run_global_ctxt(

src/librustdoc/lib.rs

@@ -31,7 +31,6 @@ extern crate tracing;
 // Dependencies listed in Cargo.toml do not need `extern crate`.
 
 extern crate rustc_ast;
-extern crate rustc_ast_lowering;
 extern crate rustc_ast_pretty;
 extern crate rustc_attr;
 extern crate rustc_data_structures;
@@ -714,6 +713,7 @@ fn main_options(options: config::Options) -> MainResult {
     let default_passes = options.default_passes;
     let output_format = options.output_format;
     // FIXME: fix this clone (especially render_options)
+    let externs = options.externs.clone();
     let manual_passes = options.manual_passes.clone();
     let render_options = options.render_options.clone();
     let config = core::create_config(options);
@@ -731,7 +731,7 @@ fn main_options(options: config::Options) -> MainResult {
             // We need to hold on to the complete resolver, so we cause everything to be
             // cloned for the analysis passes to use. Suboptimal, but necessary in the
             // current architecture.
-            let resolver = core::create_resolver(queries, &sess);
+            let resolver = core::create_resolver(externs, queries, &sess);
 
             if sess.has_errors() {
                 sess.fatal("Compilation failed, aborting rustdoc");

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -37,9 +37,6 @@ use crate::html::markdown::{markdown_links, MarkdownLink};
 use crate::lint::{BROKEN_INTRA_DOC_LINKS, PRIVATE_INTRA_DOC_LINKS};
 use crate::passes::Pass;
 
-mod early;
-crate use early::IntraLinkCrateLoader;
-
 crate const COLLECT_INTRA_DOC_LINKS: Pass = Pass {
     name: "collect-intra-doc-links",
     run: collect_intra_doc_links,

src/librustdoc/passes/mod.rs

@@ -30,7 +30,7 @@ crate use self::unindent_comments::UNINDENT_COMMENTS;
 mod propagate_doc_cfg;
 crate use self::propagate_doc_cfg::PROPAGATE_DOC_CFG;
 
-crate mod collect_intra_doc_links;
+mod collect_intra_doc_links;
 crate use self::collect_intra_doc_links::COLLECT_INTRA_DOC_LINKS;
 
 mod doc_test_lints;

src/test/rustdoc/auxiliary/issue-66159-1.rs

@@ -0,0 +1,2 @@
+/// This will be referred to by the test docstring
+pub struct Something;

src/test/rustdoc/issue-66159.rs

@@ -0,0 +1,10 @@
+// aux-crate:priv:issue_66159_1=issue-66159-1.rs
+// compile-flags:-Z unstable-options
+
+// The issue was an ICE which meant that we never actually generated the docs
+// so if we have generated the docs, we're okay.
+// Since we don't generate the docs for the auxiliary files, we can't actually
+// verify that the struct is linked correctly.
+
+// @has issue_66159/index.html
+//! [issue_66159_1::Something]