Enable "jump to def" feature on patterns

src/librustdoc/html/highlight.rs

@@ -337,7 +337,7 @@ enum Class {
     Ident(Span),
     Lifetime,
     PreludeTy(Span),
-    PreludeVal,
+    PreludeVal(Span),
     QuestionMark,
     Decoration(&'static str),
 }
@@ -385,7 +385,7 @@ impl Class {
             Class::Ident(_) => "",
             Class::Lifetime => "lifetime",
             Class::PreludeTy(_) => "prelude-ty",
-            Class::PreludeVal => "prelude-val",
+            Class::PreludeVal(_) => "prelude-val",
             Class::QuestionMark => "question-mark",
             Class::Decoration(kind) => kind,
         }
@@ -395,7 +395,11 @@ impl Class {
     /// a "span" (a tuple representing `(lo, hi)` equivalent of `Span`).
     fn get_span(self) -> Option<Span> {
         match self {
-            Self::Ident(sp) | Self::Self_(sp) | Self::Macro(sp) | Self::PreludeTy(sp) => Some(sp),
+            Self::Ident(sp)
+            | Self::Self_(sp)
+            | Self::Macro(sp)
+            | Self::PreludeTy(sp)
+            | Self::PreludeVal(sp) => Some(sp),
             Self::Comment
             | Self::DocComment
             | Self::Attribute
@@ -406,7 +410,6 @@ impl Class {
             | Self::Number
             | Self::Bool
             | Self::Lifetime
-            | Self::PreludeVal
             | Self::QuestionMark
             | Self::Decoration(_) => None,
         }
@@ -851,7 +854,9 @@ impl<'src> Classifier<'src> {
             TokenKind::Ident => match get_real_ident_class(text, false) {
                 None => match text {
                     "Option" | "Result" => Class::PreludeTy(self.new_span(before, text)),
-                    "Some" | "None" | "Ok" | "Err" => Class::PreludeVal,
+                    "Some" | "None" | "Ok" | "Err" => {
+                        Class::PreludeVal(self.new_span(before, text))
+                    }
                     // "union" is a weak keyword and is only considered as a keyword when declaring
                     // a union type.
                     "union" if self.check_if_is_union_keyword() => Class::KeyWord,

src/librustdoc/html/render/span_map.rs

@@ -4,7 +4,7 @@ use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, Visitor};
-use rustc_hir::{ExprKind, HirId, Item, ItemKind, Mod, Node};
+use rustc_hir::{ExprKind, HirId, Item, ItemKind, Mod, Node, Pat, PatKind, QPath};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::hygiene::MacroKind;
@@ -170,7 +170,7 @@ impl SpanMapVisitor<'_> {
         true
     }
 
-    fn handle_call(&mut self, hir_id: HirId, expr_hir_id: Option<HirId>, span: Span) {
+    fn infer_id(&mut self, hir_id: HirId, expr_hir_id: Option<HirId>, span: Span) {
         let hir = self.tcx.hir();
         let body_id = hir.enclosing_body_owner(hir_id);
         // FIXME: this is showing error messages for parts of the code that are not
@@ -189,6 +189,27 @@ impl SpanMapVisitor<'_> {
             self.matches.insert(span, link);
         }
     }
+
+    fn handle_pat(&mut self, p: &Pat<'_>) {
+        match p.kind {
+            PatKind::Binding(_, _, _, Some(p)) => self.handle_pat(p),
+            PatKind::Struct(qpath, _, _)
+            | PatKind::TupleStruct(qpath, _, _)
+            | PatKind::Path(qpath) => match qpath {
+                QPath::TypeRelative(_, path) if matches!(path.res, Res::Err) => {
+                    self.infer_id(path.hir_id, Some(p.hir_id), qpath.span());
+                }
+                QPath::Resolved(_, path) => self.handle_path(path),
+                _ => {}
+            },
+            PatKind::Or(pats) => {
+                for pat in pats {
+                    self.handle_pat(pat);
+                }
+            }
+            _ => {}
+        }
+    }
 }
 
 impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
@@ -206,6 +227,10 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
         intravisit::walk_path(self, path);
     }
 
+    fn visit_pat(&mut self, p: &Pat<'tcx>) {
+        self.handle_pat(p);
+    }
+
     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.
@@ -228,9 +253,9 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
     fn visit_expr(&mut self, expr: &'tcx rustc_hir::Expr<'tcx>) {
         match expr.kind {
             ExprKind::MethodCall(segment, ..) => {
-                self.handle_call(segment.hir_id, Some(expr.hir_id), segment.ident.span)
+                self.infer_id(segment.hir_id, Some(expr.hir_id), segment.ident.span)
             }
-            ExprKind::Call(call, ..) => self.handle_call(call.hir_id, None, call.span),
+            ExprKind::Call(call, ..) => self.infer_id(call.hir_id, None, call.span),
             _ => {
                 if self.handle_macro(expr.span) {
                     // We don't want to go deeper into the macro.

tests/rustdoc/jump-to-def-pats.rs

@@ -0,0 +1,52 @@
+// This test ensures that patterns also get a link generated.
+
+//@ compile-flags: -Zunstable-options --generate-link-to-definition
+
+#![crate_name = "foo"]
+
+//@ has 'src/foo/jump-to-def-pats.rs.html'
+
+use std::fmt;
+
+pub enum MyEnum<T, E> {
+    Ok(T),
+    Err(E),
+    Some(T),
+    None,
+}
+
+pub enum X {
+    A,
+}
+
+pub fn foo() -> Result<(), ()> {
+    // FIXME: would be nice to be able to check both the class and the href at the same time so
+    // we could check the text as well...
+    //@ has - '//a[@class="prelude-val"]/@href' '{{channel}}/core/result/enum.Result.html#variant.Ok'
+    //@ has - '//a[@href="{{channel}}/core/result/enum.Result.html#variant.Ok"]' 'Ok'
+    Ok(())
+}
+
+impl<T, E> fmt::Display for MyEnum<T, E> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            //@ has - '//a[@href="#12"]' 'Self::Ok'
+            Self::Ok(_) => f.write_str("MyEnum::Ok"),
+            //@ has - '//a[@href="#13"]' 'MyEnum::Err'
+            MyEnum::Err(_) => f.write_str("MyEnum::Err"),
+            //@ has - '//a[@href="#14"]' 'Self::Some'
+            Self::Some(_) => f.write_str("MyEnum::Some"),
+            //@ has - '//a[@href="#15"]' 'Self::None'
+            Self::None => f.write_str("MyEnum::None"),
+        }
+    }
+}
+
+impl X {
+    fn p(&self) -> &str {
+        match self {
+            //@ has - '//a[@href="#19"]' 'Self::A'
+            Self::A => "X::A",
+        }
+    }
+}