Rollup merge of rust-lang#113623 - GuillaumeGomez:add-jump-to-doc, r=notriddle

Add jump to doc

I'm using the source code pages of the compiler quite a lot, but one thing missing is the possibility to jump back from the source code to the item documentation. Since I also got a few others complaining about it, I think it's fine to add it since this option is nightly only.

This PR adds a link to jump back to item's documentation on the item definition (so on `Bar` in `struct Bar {... }`, as described in the unofficial [RFC](https://github.com/GuillaumeGomez/rfcs/blob/rustdoc-jump-to-definition/text/000-rustdoc-jump-to-definition.md)).

r? ````@notriddle````

Author: matthiaskrgr

src/librustdoc/html/highlight.rs

@@ -986,6 +986,11 @@ fn string_without_closing_tag<T: Display>(
                     )
                     .ok()
                     .map(|(url, _, _)| url),
+                    LinkFromSrc::Doc(def_id) => {
+                        format::href_with_root_path(*def_id, context, Some(&href_context.root_path))
+                            .ok()
+                            .map(|(doc_link, _, _)| doc_link)
+                    }
                 }
             })
         {

src/librustdoc/html/render/context.rs

@@ -349,7 +349,12 @@ impl<'tcx> Context<'tcx> {
                     let e = ExternalCrate { crate_num: cnum };
                     (e.name(self.tcx()), e.src_root(self.tcx()))
                 }
-                ExternalLocation::Unknown => return None,
+                ExternalLocation::Unknown => {
+                    let e = ExternalCrate { crate_num: cnum };
+                    let name = e.name(self.tcx());
+                    root = name.to_string();
+                    (name, e.src_root(self.tcx()))
+                }
             };
 
             let href = RefCell::new(PathBuf::new());

src/librustdoc/html/render/span_map.rs

@@ -1,11 +1,11 @@
-use crate::clean::{self, PrimitiveType};
+use crate::clean::{self, rustc_span, PrimitiveType};
 use crate::html::sources;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::def_id::DefId;
+use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, Visitor};
-use rustc_hir::{ExprKind, HirId, Mod, Node};
+use rustc_hir::{ExprKind, HirId, Item, ItemKind, Mod, Node};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::hygiene::MacroKind;
@@ -25,6 +25,7 @@ pub(crate) enum LinkFromSrc {
     Local(clean::Span),
     External(DefId),
     Primitive(PrimitiveType),
+    Doc(DefId),
 }
 
 /// This function will do at most two things:
@@ -65,24 +66,43 @@ struct SpanMapVisitor<'tcx> {
 impl<'tcx> SpanMapVisitor<'tcx> {
     /// This function is where we handle `hir::Path` elements and add them into the "span map".
     fn handle_path(&mut self, path: &rustc_hir::Path<'_>) {
-        let info = match path.res {
+        match path.res {
             // FIXME: For now, we handle `DefKind` if it's not a `DefKind::TyParam`.
             // Would be nice to support them too alongside the other `DefKind`
             // (such as primitive types!).
-            Res::Def(kind, def_id) if kind != DefKind::TyParam => Some(def_id),
-            Res::Local(_) => None,
+            Res::Def(kind, def_id) if kind != DefKind::TyParam => {
+                let link = if def_id.as_local().is_some() {
+                    LinkFromSrc::Local(rustc_span(def_id, self.tcx))
+                } else {
+                    LinkFromSrc::External(def_id)
+                };
+                self.matches.insert(path.span, link);
+            }
+            Res::Local(_) => {
+                if let Some(span) = self.tcx.hir().res_span(path.res) {
+                    self.matches.insert(path.span, LinkFromSrc::Local(clean::Span::new(span)));
+                }
+            }
             Res::PrimTy(p) => {
                 // FIXME: Doesn't handle "path-like" primitives like arrays or tuples.
                 self.matches.insert(path.span, LinkFromSrc::Primitive(PrimitiveType::from(p)));
-                return;
             }
-            Res::Err => return,
-            _ => return,
-        };
-        if let Some(span) = self.tcx.hir().res_span(path.res) {
-            self.matches.insert(path.span, LinkFromSrc::Local(clean::Span::new(span)));
-        } else if let Some(def_id) = info {
-            self.matches.insert(path.span, LinkFromSrc::External(def_id));
+            Res::Err => {}
+            _ => {}
+        }
+    }
+
+    /// Used to generate links on items' definition to go to their documentation page.
+    pub(crate) fn extract_info_from_hir_id(&mut self, hir_id: HirId) {
+        if let Some(Node::Item(item)) = self.tcx.hir().find(hir_id) {
+            if let Some(span) = self.tcx.def_ident_span(item.owner_id) {
+                let cspan = clean::Span::new(span);
+                // If the span isn't from the current crate, we ignore it.
+                if cspan.inner().is_dummy() || cspan.cnum(self.tcx.sess) != LOCAL_CRATE {
+                    return;
+                }
+                self.matches.insert(span, LinkFromSrc::Doc(item.owner_id.to_def_id()));
+            }
         }
     }
 
@@ -117,10 +137,13 @@ impl<'tcx> SpanMapVisitor<'tcx> {
             _ => return true,
         };
         let link_from_src = match data.macro_def_id {
-            Some(macro_def_id) if macro_def_id.is_local() => {
-                LinkFromSrc::Local(clean::Span::new(data.def_site))
+            Some(macro_def_id) => {
+                if macro_def_id.is_local() {
+                    LinkFromSrc::Local(clean::Span::new(data.def_site))
+                } else {
+                    LinkFromSrc::External(macro_def_id)
+                }
             }
-            Some(macro_def_id) => LinkFromSrc::External(macro_def_id),
             None => return true,
         };
         let new_span = data.call_site;
@@ -160,6 +183,9 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
                     LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)),
                 );
             }
+        } else {
+            // If it's a "mod foo {}", we want to look to its documentation page.
+            self.extract_info_from_hir_id(id);
         }
         intravisit::walk_mod(self, m, id);
     }
@@ -176,18 +202,41 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
                 .tcx
                 .typeck_body(hir.maybe_body_owned_by(body_id).expect("a body which isn't a body"));
             if let Some(def_id) = typeck_results.type_dependent_def_id(expr.hir_id) {
-                self.matches.insert(
-                    segment.ident.span,
-                    match hir.span_if_local(def_id) {
-                        Some(span) => LinkFromSrc::Local(clean::Span::new(span)),
-                        None => LinkFromSrc::External(def_id),
-                    },
-                );
+                let link = if def_id.as_local().is_some() {
+                    LinkFromSrc::Local(rustc_span(def_id, self.tcx))
+                } else {
+                    LinkFromSrc::External(def_id)
+                };
+                self.matches.insert(segment.ident.span, link);
             }
         } else if self.handle_macro(expr.span) {
             // We don't want to go deeper into the macro.
             return;
         }
         intravisit::walk_expr(self, expr);
     }
+
+    fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
+        match item.kind {
+            ItemKind::Static(_, _, _)
+            | ItemKind::Const(_, _)
+            | ItemKind::Fn(_, _, _)
+            | ItemKind::Macro(_, _)
+            | ItemKind::TyAlias(_, _)
+            | ItemKind::Enum(_, _)
+            | ItemKind::Struct(_, _)
+            | ItemKind::Union(_, _)
+            | ItemKind::Trait(_, _, _, _, _)
+            | ItemKind::TraitAlias(_, _) => self.extract_info_from_hir_id(item.hir_id()),
+            ItemKind::Impl(_)
+            | ItemKind::Use(_, _)
+            | ItemKind::ExternCrate(_)
+            | ItemKind::ForeignMod { .. }
+            | ItemKind::GlobalAsm(_)
+            | ItemKind::OpaqueTy(_)
+            // We already have "visit_mod" above so no need to check it here.
+            | ItemKind::Mod(_) => {}
+        }
+        intravisit::walk_item(self, item);
+    }
 }

tests/rustdoc-gui/source-anchor-scroll.goml

@@ -7,11 +7,11 @@ set-window-size: (600, 800)
 // We check that the scroll is at the top first.
 assert-property: ("html", {"scrollTop": "0"})
 
-click: '//a[text() = "barbar"]'
+click: '//a[text() = "barbar" and @href="#5-7"]'
 assert-property: ("html", {"scrollTop": "149"})
-click: '//a[text() = "bar"]'
+click: '//a[text() = "bar" and @href="#28-36"]'
 assert-property: ("html", {"scrollTop": "180"})
-click: '//a[text() = "sub_fn"]'
+click: '//a[text() = "sub_fn" and @href="#2-4"]'
 assert-property: ("html", {"scrollTop": "77"})
 
 // We now check that clicking on lines doesn't change the scroll

tests/rustdoc/check-source-code-urls-to-def.rs

@@ -14,10 +14,10 @@ extern crate source_code;
 #[path = "auxiliary/source-code-bar.rs"]
 pub mod bar;
 
-// @count - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#5"]' 4
+// @count - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#5-7"]' 4
 use bar::Bar;
-// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#13"]' 'self'
-// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#14"]' 'Trait'
+// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#13-17"]' 'self'
+// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#14-16"]' 'Trait'
 use bar::sub::{self, Trait};
 
 pub struct Foo;
@@ -32,7 +32,8 @@ fn babar() {}
 // @has - '//pre[@class="rust"]//a/@href' '/primitive.u32.html'
 // @has - '//pre[@class="rust"]//a/@href' '/primitive.str.html'
 // @count - '//pre[@class="rust"]//a[@href="#23"]' 5
-// @has - '//pre[@class="rust"]//a[@href="../../source_code/struct.SourceCode.html"]' 'source_code::SourceCode'
+// @has - '//pre[@class="rust"]//a[@href="../../source_code/struct.SourceCode.html"]' \
+//        'source_code::SourceCode'
 pub fn foo(a: u32, b: &str, c: String, d: Foo, e: bar::Bar, f: source_code::SourceCode) {
     let x = 12;
     let y: Foo = Foo;
@@ -42,15 +43,15 @@ pub fn foo(a: u32, b: &str, c: String, d: Foo, e: bar::Bar, f: source_code::Sour
     y.hello();
 }
 
-// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#14"]' 'bar::sub::Trait'
-// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#14"]' 'Trait'
+// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#14-16"]' 'bar::sub::Trait'
+// @has - '//pre[@class="rust"]//a[@href="auxiliary/source-code-bar.rs.html#14-16"]' 'Trait'
 pub fn foo2<T: bar::sub::Trait, V: Trait>(t: &T, v: &V, b: bool) {}
 
 pub trait AnotherTrait {}
 pub trait WhyNot {}
 
-// @has - '//pre[@class="rust"]//a[@href="#49"]' 'AnotherTrait'
-// @has - '//pre[@class="rust"]//a[@href="#50"]' 'WhyNot'
+// @has - '//pre[@class="rust"]//a[@href="#50"]' 'AnotherTrait'
+// @has - '//pre[@class="rust"]//a[@href="#51"]' 'WhyNot'
 pub fn foo3<T, V>(t: &T, v: &V)
 where
     T: AnotherTrait,
@@ -59,7 +60,7 @@ where
 
 pub trait AnotherTrait2 {}
 
-// @has - '//pre[@class="rust"]//a[@href="#60"]' 'AnotherTrait2'
+// @has - '//pre[@class="rust"]//a[@href="#61"]' 'AnotherTrait2'
 pub fn foo4() {
     let x: Vec<AnotherTrait2> = Vec::new();
 }

tests/rustdoc/jump-to-def-doc-links.rs

@@ -0,0 +1,51 @@
+// compile-flags: -Zunstable-options --generate-link-to-definition
+
+#![crate_name = "foo"]
+
+// @has 'src/foo/jump-to-def-doc-links.rs.html'
+
+// @has - '//a[@href="../../foo/struct.Bar.html"]' 'Bar'
+// @has - '//a[@href="../../foo/struct.Foo.html"]' 'Foo'
+pub struct Bar; pub struct Foo;
+
+// @has - '//a[@href="../../foo/enum.Enum.html"]' 'Enum'
+pub enum Enum {
+    Variant1(String),
+    Variant2(u8),
+}
+
+// @has - '//a[@href="../../foo/struct.Struct.html"]' 'Struct'
+pub struct Struct {
+    pub a: u8,
+    b: Foo,
+}
+
+impl Struct {
+    pub fn foo() {}
+    pub fn foo2(&self) {}
+    fn bar() {}
+    fn bar(&self) {}
+}
+
+// @has - '//a[@href="../../foo/trait.Trait.html"]' 'Trait'
+pub trait Trait {
+    fn foo();
+}
+
+impl Trait for Struct {
+    fn foo() {}
+}
+
+// @has - '//a[@href="../../foo/union.Union.html"]' 'Union'
+pub union Union {
+    pub a: u16,
+    pub f: u32,
+}
+
+// @has - '//a[@href="../../foo/fn.bar.html"]' 'bar'
+pub fn bar(b: Bar) {
+     let x = Foo;
+}
+
+// @has - '//a[@href="../../foo/bar/index.html"]' 'bar'
+pub mod bar {}