Don't suggest rewriting call if resolution was invalid

Author: compiler-errors

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -816,8 +816,13 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                 return (true, suggested_candidates, candidates);
             }
 
-            // If the first argument in call is `self` suggest calling a method.
-            if let Some((call_span, args_span)) = self.call_has_self_arg(source) {
+            // If the first argument in call is `self` suggest calling a method,
+            // even if we didn't find an associated item. However, only suggest
+            // this if there's no `Res`, since if there was a resolution but it
+            // was invalid, it's more likely not a typo of this form.
+            if let Some((call_span, args_span)) = self.call_has_self_arg(source)
+                && res.is_none()
+            {
                 let mut args_snippet = String::new();
                 if let Some(args_span) = args_span {
                     if let Ok(snippet) = self.r.tcx.sess.source_map().span_to_snippet(args_span) {
@@ -829,7 +834,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     call_span,
                     format!("try calling `{ident}` as a method"),
                     format!("self.{path_str}({args_snippet})"),
-                    Applicability::MachineApplicable,
+                    Applicability::MaybeIncorrect,
                 );
                 return (true, suggested_candidates, candidates);
             }

tests/ui/privacy/ctor-private-from-impl.rs

@@ -0,0 +1,18 @@
+pub struct MyStruct {}
+
+mod submodule {
+    use super::MyStruct;
+
+    pub struct MyRef<'a>(&'a MyStruct);
+}
+
+use self::submodule::MyRef;
+
+impl MyStruct {
+    pub fn method(&self) -> MyRef {
+        MyRef(self)
+        //~^ ERROR cannot initialize a tuple struct which contains private fields
+    }
+}
+
+fn main() {}

tests/ui/privacy/ctor-private-from-impl.stderr

@@ -0,0 +1,35 @@
+error[E0423]: cannot initialize a tuple struct which contains private fields
+  --> $DIR/ctor-private-from-impl.rs:13:9
+   |
+LL |         MyRef(self)
+   |         ^^^^^
+   |
+note: constructor is not visible here due to private fields
+  --> $DIR/ctor-private-from-impl.rs:6:26
+   |
+LL |     pub struct MyRef<'a>(&'a MyStruct); // <- Private field; private constructor
+   |                          ^^^^^^^^^^^^ private field
+help: consider making the field publicly accessible
+   |
+LL |     pub struct MyRef<'a>(pub &'a MyStruct); // <- Private field; private constructor
+   |                          +++
+
+error[E0423]: cannot initialize a tuple struct which contains private fields
+  --> $DIR/ctor-private-from-impl.rs:19:5
+   |
+LL |     MyRef(my_struct)
+   |     ^^^^^
+   |
+note: constructor is not visible here due to private fields
+  --> $DIR/ctor-private-from-impl.rs:6:26
+   |
+LL |     pub struct MyRef<'a>(&'a MyStruct); // <- Private field; private constructor
+   |                          ^^^^^^^^^^^^ private field
+help: consider making the field publicly accessible
+   |
+LL |     pub struct MyRef<'a>(pub &'a MyStruct); // <- Private field; private constructor
+   |                          +++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0423`.