Auto merge of #89293 - TaKO8Ki:fix-confusing-error-for-path-separator-to-refer-to-an-struct-item, r=estebank

Suggest using the path separator for tuple struct

Fix confusing error message `constructor is not visible here due to private fields` for tuple struct

closes #83450

Author: bors

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1026,9 +1026,15 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
 
                 self.suggest_using_enum_variant(err, source, def_id, span);
             }
-            (Res::Def(DefKind::Struct, def_id), _) if ns == ValueNS => {
+            (Res::Def(DefKind::Struct, def_id), source) if ns == ValueNS => {
                 let (ctor_def, ctor_vis, fields) =
                     if let Some(struct_ctor) = self.r.struct_constructors.get(&def_id).cloned() {
+                        if let PathSource::Expr(Some(parent)) = source {
+                            if let ExprKind::Field(..) | ExprKind::MethodCall(..) = parent.kind {
+                                bad_struct_syntax_suggestion(def_id);
+                                return true;
+                            }
+                        }
                         struct_ctor
                     } else {
                         bad_struct_syntax_suggestion(def_id);

src/test/ui/resolve/suggest-path-for-tuple-struct.rs

@@ -0,0 +1,26 @@
+mod module {
+    pub struct SomeTupleStruct(u8);
+    pub struct SomeRegularStruct {
+        foo: u8
+    }
+
+    impl SomeTupleStruct {
+        pub fn new() -> Self {
+            Self(0)
+        }
+    }
+    impl SomeRegularStruct {
+        pub fn new() -> Self {
+            Self { foo: 0 }
+        }
+    }
+}
+
+use module::{SomeTupleStruct, SomeRegularStruct};
+
+fn main() {
+    let _ = SomeTupleStruct.new();
+    //~^ ERROR expected value, found struct `SomeTupleStruct`
+    let _ = SomeRegularStruct.new();
+    //~^ ERROR expected value, found struct `SomeRegularStruct`
+}

src/test/ui/resolve/suggest-path-for-tuple-struct.stderr

@@ -0,0 +1,19 @@
+error[E0423]: expected value, found struct `SomeTupleStruct`
+  --> $DIR/suggest-path-for-tuple-struct.rs:22:13
+   |
+LL |     let _ = SomeTupleStruct.new();
+   |             ^^^^^^^^^^^^^^^----
+   |             |
+   |             help: use the path separator to refer to an item: `SomeTupleStruct::new`
+
+error[E0423]: expected value, found struct `SomeRegularStruct`
+  --> $DIR/suggest-path-for-tuple-struct.rs:24:13
+   |
+LL |     let _ = SomeRegularStruct.new();
+   |             ^^^^^^^^^^^^^^^^^----
+   |             |
+   |             help: use the path separator to refer to an item: `SomeRegularStruct::new`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0423`.