fix: fix issue 143740, Wrong messages from compiler confusing methods with the same name from different traits

Author: lichuang

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1649,7 +1649,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 }
             }
 
-            let sources = candidates.iter().map(|p| self.candidate_source(p, self_ty)).collect();
+            let sources =
+                applicable_candidates.iter().map(|p| self.candidate_source(p.0, self_ty)).collect();
             return Some(Err(MethodError::Ambiguity(sources)));
         }
 

tests/ui/methods/wrong-ambig-message.rs

@@ -0,0 +1,33 @@
+fn main() {
+    trait Hello {
+        fn name(&self) -> String;
+    }
+
+    #[derive(Debug)]
+    struct Container2 {
+        val: String,
+    }
+
+    trait AName2 {
+        fn name(&self) -> String;
+    }
+
+    trait BName2 {
+        fn name(&self, v: bool) -> String;
+    }
+
+    impl AName2 for Container2 {
+        fn name(&self) -> String {
+            "aname2".into()
+        }
+    }
+
+    impl BName2 for Container2 {
+        fn name(&self, v: bool) -> String {
+            "bname2".into()
+        }
+    }
+
+    let c2 = Container2 { val: "abc".into() };
+    println!("c2 = {:?}", c2.name());
+}

tests/ui/methods/wrong-ambig-message.stderr

@@ -0,0 +1,38 @@
+error[E0034]: multiple applicable items in scope
+  --> tests/ui/issues/issue-143740.rs:32:30
+   |
+32 |     println!("c2 = {:?}", c2.name());
+   |                              ^^^^ multiple `name` found
+   |
+note: candidate #1 is defined in an impl of the trait `AName2` for the type `Container2`
+  --> tests/ui/issues/issue-143740.rs:20:9
+   |
+20 |         fn name(&self) -> String {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+note: candidate #2 is defined in an impl of the trait `BName2` for the type `Container2`
+  --> tests/ui/issues/issue-143740.rs:26:9
+   |
+26 |         fn name(&self, v: bool) -> String {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: disambiguate the method for candidate #1
+   |
+32 -     println!("c2 = {:?}", c2.name());
+32 +     println!("c2 = {:?}", AName2::name(&c2));
+   |
+help: disambiguate the method for candidate #2
+   |
+32 -     println!("c2 = {:?}", c2.name());
+32 +     println!("c2 = {:?}", BName2::name(&c2));
+   |
+
+warning: unused variable: `v`
+  --> tests/ui/issues/issue-143740.rs:26:24
+   |
+26 |         fn name(&self, v: bool) -> String {
+   |                        ^ help: if this is intentional, prefix it with an underscore: `_v`
+   |
+   = note: `#[warn(unused_variables)]` on by default
+
+error: aborting due to 1 previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0034`.