Consider doc(alias) when providing typo suggestions

compiler/rustc_hir_typeck/src/method/mod.rs

@@ -76,7 +76,7 @@ pub struct NoMatchData<'tcx> {
     pub unsatisfied_predicates:
         Vec<(ty::Predicate<'tcx>, Option<ty::Predicate<'tcx>>, Option<ObligationCause<'tcx>>)>,
     pub out_of_scope_traits: Vec<DefId>,
-    pub lev_candidate: Option<ty::AssocItem>,
+    pub similar_candidate: Option<ty::AssocItem>,
     pub mode: probe::Mode,
 }
 

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -461,7 +461,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     static_candidates: Vec::new(),
                     unsatisfied_predicates: Vec::new(),
                     out_of_scope_traits: Vec::new(),
-                    lev_candidate: None,
+                    similar_candidate: None,
                     mode,
                 }));
             }
@@ -1076,13 +1076,13 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         if let Some((kind, def_id)) = private_candidate {
             return Err(MethodError::PrivateMatch(kind, def_id, out_of_scope_traits));
         }
-        let lev_candidate = self.probe_for_lev_candidate()?;
+        let similar_candidate = self.probe_for_similar_candidate()?;
 
         Err(MethodError::NoMatch(NoMatchData {
             static_candidates,
             unsatisfied_predicates,
             out_of_scope_traits,
-            lev_candidate,
+            similar_candidate,
             mode: self.mode,
         }))
     }
@@ -1787,7 +1787,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     /// Similarly to `probe_for_return_type`, this method attempts to find the best matching
     /// candidate method where the method name may have been misspelled. Similarly to other
     /// Levenshtein based suggestions, we provide at most one such suggestion.
-    fn probe_for_lev_candidate(&mut self) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {
+    fn probe_for_similar_candidate(&mut self) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {
         debug!("probing for method names similar to {:?}", self.method_name);
 
         let steps = self.steps.clone();
@@ -1831,6 +1831,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         None,
                     )
                 }
+                .or_else(|| {
+                    applicable_close_candidates
+                        .iter()
+                        .find(|cand| self.matches_by_doc_alias(cand.def_id))
+                        .map(|cand| cand.name)
+                })
                 .unwrap();
                 Ok(applicable_close_candidates.into_iter().find(|method| method.name == best_name))
             }
@@ -1981,6 +1987,38 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    /// Determine if the associated item withe the given DefId matches
+    /// the desired name via a doc alias.
+    fn matches_by_doc_alias(&self, def_id: DefId) -> bool {
+        let Some(name) = self.method_name else { return false; };
+        let Some(local_def_id) = def_id.as_local() else { return false; };
+        let hir_id = self.fcx.tcx.hir().local_def_id_to_hir_id(local_def_id);
+        let attrs = self.fcx.tcx.hir().attrs(hir_id);
+        for attr in attrs {
+            let sym::doc = attr.name_or_empty() else { continue; };
+            let Some(values) = attr.meta_item_list() else { continue; };
+            for v in values {
+                if v.name_or_empty() != sym::alias {
+                    continue;
+                }
+                if let Some(nested) = v.meta_item_list() {
+                    // #[doc(alias("foo", "bar"))]
+                    for n in nested {
+                        if let Some(lit) = n.lit() && name.as_str() == lit.symbol.as_str() {
+                            return true;
+                        }
+                    }
+                } else if let Some(meta) = v.meta_item()
+                    && let Some(lit) = meta.name_value_literal()
+                    && name.as_str() == lit.symbol.as_str() {
+                        // #[doc(alias = "foo")]
+                        return true;
+                }
+            }
+        }
+        false
+    }
+
     /// Finds the method with the appropriate name (or return type, as the case may be). If
     /// `allow_similar_names` is set, find methods with close-matching names.
     // The length of the returned iterator is nearly always 0 or 1 and this
@@ -1996,6 +2034,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         if !self.is_relevant_kind_for_mode(x.kind) {
                             return false;
                         }
+                        if self.matches_by_doc_alias(x.def_id) {
+                            return true;
+                        }
                         match lev_distance_with_substrings(name.as_str(), x.name.as_str(), max_dist)
                         {
                             Some(d) => d > 0,

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -262,7 +262,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let ty_str = with_forced_trimmed_paths!(self.ty_to_string(rcvr_ty));
         let is_method = mode == Mode::MethodCall;
         let unsatisfied_predicates = &no_match_data.unsatisfied_predicates;
-        let lev_candidate = no_match_data.lev_candidate;
+        let similar_candidate = no_match_data.similar_candidate;
         let item_kind = if is_method {
             "method"
         } else if rcvr_ty.is_enum() {
@@ -937,7 +937,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // give a helping note that it has to be called as `(x.f)(...)`.
         if let SelfSource::MethodCall(expr) = source {
             if !self.suggest_calling_field_as_fn(span, rcvr_ty, expr, item_name, &mut err)
-                && lev_candidate.is_none()
+                && similar_candidate.is_none()
                 && !custom_span_label
             {
                 label_span_not_found(&mut err);
@@ -1015,20 +1015,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if fallback_span {
                 err.span_label(span, msg);
             }
-        } else if let Some(lev_candidate) = lev_candidate {
+        } else if let Some(similar_candidate) = similar_candidate {
             // Don't emit a suggestion if we found an actual method
             // that had unsatisfied trait bounds
             if unsatisfied_predicates.is_empty() {
-                let def_kind = lev_candidate.kind.as_def_kind();
+                let def_kind = similar_candidate.kind.as_def_kind();
                 // Methods are defined within the context of a struct and their first parameter is always self,
                 // which represents the instance of the struct the method is being called on
                 // Associated functions don’t take self as a parameter and
                 // they are not methods because they don’t have an instance of the struct to work with.
-                if def_kind == DefKind::AssocFn && lev_candidate.fn_has_self_parameter {
+                if def_kind == DefKind::AssocFn && similar_candidate.fn_has_self_parameter {
                     err.span_suggestion(
                         span,
                         "there is a method with a similar name",
-                        lev_candidate.name,
+                        similar_candidate.name,
                         Applicability::MaybeIncorrect,
                     );
                 } else {
@@ -1037,9 +1037,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         &format!(
                             "there is {} {} with a similar name",
                             def_kind.article(),
-                            def_kind.descr(lev_candidate.def_id),
+                            def_kind.descr(similar_candidate.def_id),
                         ),
-                        lev_candidate.name,
+                        similar_candidate.name,
                         Applicability::MaybeIncorrect,
                     );
                 }

tests/ui/methods/method-not-found-but-doc-alias.rs

@@ -0,0 +1,11 @@
+struct Foo;
+
+impl Foo {
+    #[doc(alias = "quux")]
+    fn bar(&self) {}
+}
+
+fn main() {
+    Foo.quux();
+    //~^ ERROR  no method named `quux` found for struct `Foo` in the current scope
+}

tests/ui/methods/method-not-found-but-doc-alias.stderr

@@ -0,0 +1,12 @@
+error[E0599]: no method named `quux` found for struct `Foo` in the current scope
+  --> $DIR/method-not-found-but-doc-alias.rs:9:9
+   |
+LL | struct Foo;
+   | ---------- method `quux` not found for this struct
+...
+LL |     Foo.quux();
+   |         ^^^^ help: there is a method with a similar name: `bar`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.