Auto merge of #112239 - jieyouxu:targeted-no-method-suggestions, r=cjgillot

Add `#[rustc_confusables]` attribute to allow targeted "no method" error suggestions on standard library types

After this PR, the standard library developer can annotate methods on e.g. `BTreeSet::push` with `#[rustc_confusables("insert")]`. When the user mistypes `btreeset.push()`, `BTreeSet::insert` will be suggested if there are no other candidates to suggest. This PR lays the foundations for contributors to add `rustc_confusables` annotations to standard library types for targeted suggestions, as specified in #59450, or to address cases such as #108437.

### Example

Assume `BTreeSet` is the standard library type:

```
// Standard library definition
#![feature(rustc_attrs)]

struct BTreeSet;

impl BTreeSet {
    #[rustc_confusables("push")]
    fn insert(&self) {}
}

// User code
fn main() {
    let x = BTreeSet {};
    x.push();
}
```

A new suggestion (which has lower precedence than suggestions for misspellings and only is shown when there are no misspellings suggestions) will be added to hint the user maybe they intended to write `x.insert()` instead:

```
error[E0599]: no method named `push` found for struct `BTreeSet` in the current scope
  --> test.rs:12:7
   |
3  | struct BTreeSet;
   | --------------- method `push` not found for this struct
...
12 |     x.push();
   |       ^^^^ method not found in `BTreeSet`
   |
help: you might have meant to use `insert`
   |
12 |     x.insert();
   |       ~~~~~~

error: aborting due to previous error
```

12 files changed, 259 insertions, 4 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 9f1561b503d..2390850b567 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3665,6 +3665,7 @@ name = "rustc_hir_typeck"
 version = "0.1.0"
 dependencies = [
  "rustc_ast",
+ "rustc_attr",
  "rustc_data_structures",
  "rustc_errors",
  "rustc_fluent_macro",
diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index 372a58857f3..6cce3a56f08 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -1217,3 +1217,20 @@ pub fn parse_alignment(node: &ast::LitKind) -> Result<u32, &'static str> {
         Err("not an unsuffixed integer")
     }
 }
+
+/// Read the content of a `rustc_confusables` attribute, and return the list of candidate names.
+pub fn parse_confusables(attr: &Attribute) -> Option<Vec<Symbol>> {
+    let meta = attr.meta()?;
+    let MetaItem { kind: MetaItemKind::List(ref metas), .. } = meta else { return None };
+
+    let mut candidates = Vec::new();
+
+    for meta in metas {
+        let NestedMetaItem::Lit(meta_lit) = meta else {
+            return None;
+        };
+        candidates.push(meta_lit.symbol);
+    }
+
+    return Some(candidates);
+}
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index a70671dd9fb..a183cfd8776 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -625,6 +625,12 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         ErrorFollowing,
         INTERNAL_UNSTABLE
     ),
+    rustc_attr!(
+        rustc_confusables, Normal,
+        template!(List: r#""name1", "name2", ..."#),
+        ErrorFollowing,
+        INTERNAL_UNSTABLE,
+    ),
     // Enumerates "identity-like" conversion methods to suggest on type mismatch.
     rustc_attr!(
         rustc_conversion_suggestion, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE
diff --git a/compiler/rustc_hir_typeck/Cargo.toml b/compiler/rustc_hir_typeck/Cargo.toml
index 13e1ea31c4d..ce91d023a0a 100644
--- a/compiler/rustc_hir_typeck/Cargo.toml
+++ b/compiler/rustc_hir_typeck/Cargo.toml
@@ -9,6 +9,7 @@ edition = "2021"
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 tracing = "0.1"
 rustc_ast = { path = "../rustc_ast" }
+rustc_attr = { path = "../rustc_attr" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_graphviz = { path = "../rustc_graphviz" }
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index e3e0eff23d2..3d7187cb16f 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -2,13 +2,12 @@
 //! found or is otherwise invalid.
 
 use crate::errors;
-use crate::errors::CandidateTraitNote;
-use crate::errors::NoAssociatedItem;
+use crate::errors::{CandidateTraitNote, NoAssociatedItem};
 use crate::Expectation;
 use crate::FnCtxt;
 use rustc_ast::ast::Mutability;
-use rustc_data_structures::fx::FxIndexMap;
-use rustc_data_structures::fx::FxIndexSet;
+use rustc_attr::parse_confusables;
+use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::StashKey;
 use rustc_errors::{
@@ -1038,6 +1037,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             "the {item_kind} was found for\n{}{}",
                             type_candidates, additional_types
                         ));
+                    } else {
+                        'outer: for inherent_impl_did in self.tcx.inherent_impls(adt.did()) {
+                            for inherent_method in
+                                self.tcx.associated_items(inherent_impl_did).in_definition_order()
+                            {
+                                if let Some(attr) = self.tcx.get_attr(inherent_method.def_id, sym::rustc_confusables)
+                                    && let Some(candidates) = parse_confusables(attr)
+                                    && candidates.contains(&item_name.name)
+                                {
+                                    err.span_suggestion_verbose(
+                                        item_name.span,
+                                        format!(
+                                            "you might have meant to use `{}`",
+                                            inherent_method.name.as_str()
+                                        ),
+                                        inherent_method.name.as_str(),
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                    break 'outer;
+                                }
+                            }
+                        }
                     }
                 }
             } else {
diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
index a607e483c97..0aa3d6265dc 100644
--- a/compiler/rustc_passes/messages.ftl
+++ b/compiler/rustc_passes/messages.ftl
@@ -98,6 +98,9 @@ passes_collapse_debuginfo =
     `collapse_debuginfo` attribute should be applied to macro definitions
     .label = not a macro definition
 
+passes_confusables = attribute should be applied to an inherent method
+    .label = not an inherent method
+
 passes_const_impl_const_trait =
     const `impl`s must be for traits marked with `#[const_trait]`
     .note = this trait must be annotated with `#[const_trait]`
@@ -266,6 +269,9 @@ passes_duplicate_lang_item_crate_depends =
     .first_definition_path = first definition in `{$orig_crate_name}` loaded from {$orig_path}
     .second_definition_path = second definition in `{$crate_name}` loaded from {$path}
 
+passes_empty_confusables =
+    expected at least one confusable name
+
 passes_export_name =
     attribute should be applied to a free function, impl method or static
     .label = not a free function, impl method or static
@@ -326,6 +332,9 @@ passes_implied_feature_not_exist =
 passes_incorrect_do_not_recommend_location =
     `#[do_not_recommend]` can only be placed on trait implementations
 
+passes_incorrect_meta_item = expected a quoted string literal
+passes_incorrect_meta_item_suggestion = consider surrounding this with quotes
+
 passes_incorrect_target =
     `{$name}` language item must be applied to a {$kind} with {$at_least ->
         [true] at least {$num}
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index ee14ffa6da8..4d7ebe3fefe 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -183,6 +183,7 @@ impl CheckAttrVisitor<'_> {
                 | sym::rustc_allowed_through_unstable_modules
                 | sym::rustc_promotable => self.check_stability_promotable(&attr, span, target),
                 sym::link_ordinal => self.check_link_ordinal(&attr, span, target),
+                sym::rustc_confusables => self.check_confusables(&attr, target),
                 _ => true,
             };
 
@@ -1985,6 +1986,46 @@ impl CheckAttrVisitor<'_> {
         }
     }
 
+    fn check_confusables(&self, attr: &Attribute, target: Target) -> bool {
+        match target {
+            Target::Method(MethodKind::Inherent) => {
+                let Some(meta) = attr.meta() else {
+                    return false;
+                };
+                let ast::MetaItem { kind: MetaItemKind::List(ref metas), .. } = meta else {
+                    return false;
+                };
+
+                let mut candidates = Vec::new();
+
+                for meta in metas {
+                    let NestedMetaItem::Lit(meta_lit) = meta else {
+                        self.tcx.sess.emit_err(errors::IncorrectMetaItem {
+                            span: meta.span(),
+                            suggestion: errors::IncorrectMetaItemSuggestion {
+                                lo: meta.span().shrink_to_lo(),
+                                hi: meta.span().shrink_to_hi(),
+                            },
+                        });
+                        return false;
+                    };
+                    candidates.push(meta_lit.symbol);
+                }
+
+                if candidates.is_empty() {
+                    self.tcx.sess.emit_err(errors::EmptyConfusables { span: attr.span });
+                    return false;
+                }
+
+                true
+            }
+            _ => {
+                self.tcx.sess.emit_err(errors::Confusables { attr_span: attr.span });
+                false
+            }
+        }
+    }
+
     fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
         match target {
             Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 3fe7feb9dfa..eae13f86049 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -618,6 +618,38 @@ pub struct LinkOrdinal {
 }
 
 #[derive(Diagnostic)]
+#[diag(passes_confusables)]
+pub struct Confusables {
+    #[primary_span]
+    pub attr_span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_empty_confusables)]
+pub(crate) struct EmptyConfusables {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_incorrect_meta_item, code = "E0539")]
+pub(crate) struct IncorrectMetaItem {
+    #[primary_span]
+    pub span: Span,
+    #[subdiagnostic]
+    pub suggestion: IncorrectMetaItemSuggestion,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(passes_incorrect_meta_item_suggestion, applicability = "maybe-incorrect")]
+pub(crate) struct IncorrectMetaItemSuggestion {
+    #[suggestion_part(code = "\"")]
+    pub lo: Span,
+    #[suggestion_part(code = "\"")]
+    pub hi: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(passes_stability_promotable)]
 pub struct StabilityPromotable {
     #[primary_span]
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 4fc440ef947..08925761b39 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1265,6 +1265,7 @@ symbols! {
         rustc_clean,
         rustc_coherence_is_core,
         rustc_coinductive,
+        rustc_confusables,
         rustc_const_stable,
         rustc_const_unstable,
         rustc_conversion_suggestion,
diff --git a/tests/ui/attributes/auxiliary/rustc_confusables_across_crate.rs b/tests/ui/attributes/auxiliary/rustc_confusables_across_crate.rs
new file mode 100644
index 00000000000..2fb2d3ad4c4
--- /dev/null
+++ b/tests/ui/attributes/auxiliary/rustc_confusables_across_crate.rs
@@ -0,0 +1,11 @@
+#![feature(rustc_attrs)]
+
+pub struct BTreeSet;
+
+impl BTreeSet {
+    #[rustc_confusables("push", "test_b")]
+    pub fn insert(&self) {}
+
+    #[rustc_confusables("pulled")]
+    pub fn pull(&self) {}
+}
diff --git a/tests/ui/attributes/rustc_confusables.rs b/tests/ui/attributes/rustc_confusables.rs
new file mode 100644
index 00000000000..352e91d065f
--- /dev/null
+++ b/tests/ui/attributes/rustc_confusables.rs
@@ -0,0 +1,47 @@
+// aux-build: rustc_confusables_across_crate.rs
+
+#![feature(rustc_attrs)]
+
+extern crate rustc_confusables_across_crate;
+
+use rustc_confusables_across_crate::BTreeSet;
+
+fn main() {
+    // Misspellings (similarly named methods) take precedence over `rustc_confusables`.
+    let x = BTreeSet {};
+    x.inser();
+    //~^ ERROR no method named
+    //~| HELP there is a method with a similar name
+    x.foo();
+    //~^ ERROR no method named
+    x.push();
+    //~^ ERROR no method named
+    //~| HELP you might have meant to use `insert`
+    x.test();
+    //~^ ERROR no method named
+    x.pulled();
+    //~^ ERROR no method named
+    //~| HELP there is a method with a similar name
+}
+
+struct Bar;
+
+impl Bar {
+    #[rustc_confusables()]
+    //~^ ERROR expected at least one confusable name
+    fn baz() {}
+
+    #[rustc_confusables]
+    //~^ ERROR malformed `rustc_confusables` attribute input
+    //~| HELP must be of the form
+    fn qux() {}
+
+    #[rustc_confusables(invalid_meta_item)]
+    //~^ ERROR expected a quoted string literal
+    //~| HELP consider surrounding this with quotes
+    fn quux() {}
+}
+
+#[rustc_confusables("blah")]
+//~^ ERROR attribute should be applied to an inherent method
+fn not_inherent_impl_method() {}
diff --git a/tests/ui/attributes/rustc_confusables.stderr b/tests/ui/attributes/rustc_confusables.stderr
new file mode 100644
index 00000000000..9fd4470cdbb
--- /dev/null
+++ b/tests/ui/attributes/rustc_confusables.stderr
@@ -0,0 +1,68 @@
+error: malformed `rustc_confusables` attribute input
+  --> $DIR/rustc_confusables.rs:34:5
+   |
+LL |     #[rustc_confusables]
+   |     ^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_confusables("name1", "name2", ...)]`
+
+error: attribute should be applied to an inherent method
+  --> $DIR/rustc_confusables.rs:45:1
+   |
+LL | #[rustc_confusables("blah")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: expected at least one confusable name
+  --> $DIR/rustc_confusables.rs:30:5
+   |
+LL |     #[rustc_confusables()]
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0539]: expected a quoted string literal
+  --> $DIR/rustc_confusables.rs:39:25
+   |
+LL |     #[rustc_confusables(invalid_meta_item)]
+   |                         ^^^^^^^^^^^^^^^^^
+   |
+help: consider surrounding this with quotes
+   |
+LL |     #[rustc_confusables("invalid_meta_item")]
+   |                         +                 +
+
+error[E0599]: no method named `inser` found for struct `rustc_confusables_across_crate::BTreeSet` in the current scope
+  --> $DIR/rustc_confusables.rs:12:7
+   |
+LL |     x.inser();
+   |       ^^^^^ help: there is a method with a similar name: `insert`
+
+error[E0599]: no method named `foo` found for struct `rustc_confusables_across_crate::BTreeSet` in the current scope
+  --> $DIR/rustc_confusables.rs:15:7
+   |
+LL |     x.foo();
+   |       ^^^ method not found in `BTreeSet`
+
+error[E0599]: no method named `push` found for struct `rustc_confusables_across_crate::BTreeSet` in the current scope
+  --> $DIR/rustc_confusables.rs:17:7
+   |
+LL |     x.push();
+   |       ^^^^ method not found in `BTreeSet`
+   |
+help: you might have meant to use `insert`
+   |
+LL |     x.insert();
+   |       ~~~~~~
+
+error[E0599]: no method named `test` found for struct `rustc_confusables_across_crate::BTreeSet` in the current scope
+  --> $DIR/rustc_confusables.rs:20:7
+   |
+LL |     x.test();
+   |       ^^^^ method not found in `BTreeSet`
+
+error[E0599]: no method named `pulled` found for struct `rustc_confusables_across_crate::BTreeSet` in the current scope
+  --> $DIR/rustc_confusables.rs:22:7
+   |
+LL |     x.pulled();
+   |       ^^^^^^ help: there is a method with a similar name: `pull`
+
+error: aborting due to 9 previous errors
+
+Some errors have detailed explanations: E0539, E0599.
+For more information about an error, try `rustc --explain E0539`.