From 1abb7faddb406d5b40ecca39a6395957ccf9c778 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Tue, 13 Apr 2021 22:51:56 +0200
Subject: [PATCH] Generate links for modules as well

---
 src/librustdoc/html/render/span_map.rs        | 29 +++++++++++++++----
 .../rustdoc/check-source-code-urls-to-def.rs  |  9 +++---
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/src/librustdoc/html/render/span_map.rs b/src/librustdoc/html/render/span_map.rs
index 2895b4abfb2..6100f45e998 100644
--- a/src/librustdoc/html/render/span_map.rs
+++ b/src/librustdoc/html/render/span_map.rs
@@ -5,7 +5,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
-use rustc_hir::{ExprKind, GenericParam, GenericParamKind, HirId};
+use rustc_hir::{ExprKind, GenericParam, GenericParamKind, HirId, Mod, Node};
 use rustc_middle::ty::TyCtxt;
 use rustc_span::Span;
 
@@ -20,14 +20,14 @@ crate fn collect_spans_and_sources(
     krate: clean::Crate,
     src_root: &std::path::Path,
     include_sources: bool,
-    _generate_link_to_definition: bool,
+    generate_link_to_definition: bool,
 ) -> (clean::Crate, FxHashMap<std::path::PathBuf, String>, FxHashMap<(u32, u32), LinkFromSrc>) {
     let mut visitor = SpanMapVisitor { tcx, matches: FxHashMap::default() };
 
     if include_sources {
-        // if generate_link_to_definition {
-        intravisit::walk_crate(&mut visitor, tcx.hir().krate());
-        // }
+        if generate_link_to_definition {
+            intravisit::walk_crate(&mut visitor, tcx.hir().krate());
+        }
         let (krate, sources) = sources::collect_local_sources(tcx, src_root, krate);
         (krate, sources, visitor.matches)
     } else {
@@ -94,6 +94,25 @@ impl Visitor<'tcx> for SpanMapVisitor<'tcx> {
         intravisit::walk_path(self, path);
     }
 
+    fn visit_mod(&mut self, m: &'tcx Mod<'tcx>, span: Span, id: HirId) {
+        // To make the difference between "mod foo {}" and "mod foo;". In case we "import" another
+        // file, we want to link to it. Otherwise no need to create a link.
+        if !span.overlaps(m.inner) {
+            // Now that we confirmed it's a file import, we want to get the span for the module
+            // name only and not all the "mod foo;".
+            if let Some(node) = self.tcx.hir().find(id) {
+                match node {
+                    Node::Item(item) => {
+                        self.matches
+                            .insert(span_to_tuple(item.ident.span), LinkFromSrc::Local(m.inner));
+                    }
+                    _ => {}
+                }
+            }
+        }
+        intravisit::walk_mod(self, m, id);
+    }
+
     fn visit_expr(&mut self, expr: &'tcx rustc_hir::Expr<'tcx>) {
         match expr.kind {
             ExprKind::MethodCall(segment, method_span, _, _) => {
diff --git a/src/test/rustdoc/check-source-code-urls-to-def.rs b/src/test/rustdoc/check-source-code-urls-to-def.rs
index 32973ba3faf..5caef29fede 100644
--- a/src/test/rustdoc/check-source-code-urls-to-def.rs
+++ b/src/test/rustdoc/check-source-code-urls-to-def.rs
@@ -2,11 +2,12 @@
 
 #![crate_name = "foo"]
 
+// @has 'src/foo/check-source-code-urls-to-def.rs.html'
+
+// @has - '//a[@href="../../src/foo/auxiliary/source-code-bar.rs.html#1-17"]' 'bar'
 #[path = "auxiliary/source-code-bar.rs"]
 pub mod bar;
 
-// @has 'src/foo/check-source-code-urls-to-def.rs.html'
-
 // @count - '//a[@href="../../src/foo/auxiliary/source-code-bar.rs.html#5-7"]' 4
 use bar::Bar;
 // @has - '//a[@href="../../src/foo/auxiliary/source-code-bar.rs.html#13-17"]' 'self'
@@ -22,13 +23,13 @@ impl Foo {
 fn babar() {}
 
 // @has - '//a[@href="https://doc.rust-lang.org/nightly/alloc/string/struct.String.html"]' 'String'
-// @count - '//a[@href="../../src/foo/check-source-code-urls-to-def.rs.html#16"]' 5
+// @count - '//a[@href="../../src/foo/check-source-code-urls-to-def.rs.html#17"]' 5
 pub fn foo(a: u32, b: &str, c: String, d: Foo, e: bar::Bar) {
     let x = 12;
     let y: Foo = Foo;
     let z: Bar = bar::Bar { field: Foo };
     babar();
-    // @has - '//a[@href="../../src/foo/check-source-code-urls-to-def.rs.html#19"]' 'hello'
+    // @has - '//a[@href="../../src/foo/check-source-code-urls-to-def.rs.html#20"]' 'hello'
     y.hello();
 }