unify errors for tuple/struct variants

fix #63983

Author: Guanqun Lu

src/librustc_resolve/late/diagnostics.rs

@@ -445,6 +445,12 @@ impl<'a> LateResolutionVisitor<'a, '_> {
             (Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _), _) if ns == ValueNS => {
                 bad_struct_syntax_suggestion();
             }
+            (Res::Def(DefKind::Ctor(_, CtorKind::Fn), _), _) if ns == ValueNS => {
+                err.span_label(
+                    span,
+                    format!("did you mean `{} ( /* fields */ )`?", path_str),
+                );
+            }
             (Res::SelfTy(..), _) if ns == ValueNS => {
                 err.span_label(span, fallback_label);
                 err.note("can't use `Self` as a constructor, you must use the implemented struct");

src/test/ui/empty/empty-struct-tuple-pat.stderr

@@ -20,15 +20,16 @@ error[E0532]: expected unit struct/variant or constant, found tuple variant `E::
   --> $DIR/empty-struct-tuple-pat.rs:29:9
    |
 LL |         E::Empty4 => ()
-   |         ^^^^^^^^^ not a unit struct/variant or constant
+   |         ^^^^^^^^^ did you mean `E::Empty4 ( /* fields */ )`?
 
 error[E0532]: expected unit struct/variant or constant, found tuple variant `XE::XEmpty5`
   --> $DIR/empty-struct-tuple-pat.rs:33:9
    |
 LL |         XE::XEmpty5 => (),
    |         ^^^^-------
-   |             |
-   |             help: a unit variant with a similar name exists: `XEmpty4`
+   |         |   |
+   |         |   help: a unit variant with a similar name exists: `XEmpty4`
+   |         did you mean `XE::XEmpty5 ( /* fields */ )`?
 
 error: aborting due to 4 previous errors
 

src/test/ui/issues/issue-32004.stderr

@@ -3,8 +3,9 @@ error[E0532]: expected unit struct/variant or constant, found tuple variant `Foo
    |
 LL |         Foo::Bar => {}
    |         ^^^^^---
-   |              |
-   |              help: a unit variant with a similar name exists: `Baz`
+   |         |    |
+   |         |    help: a unit variant with a similar name exists: `Baz`
+   |         did you mean `Foo::Bar ( /* fields */ )`?
 
 error[E0532]: expected tuple struct/variant, found unit struct `S`
   --> $DIR/issue-32004.rs:16:9

src/test/ui/issues/issue-63983.rs

@@ -0,0 +1,15 @@
+enum MyEnum {
+    Tuple(i32),
+    Struct{ s: i32 },
+}
+
+fn foo(en: MyEnum) {
+    match en {
+        MyEnum::Tuple => "",
+        //~^ ERROR expected unit struct/variant or constant, found tuple variant `MyEnum::Tuple`
+        MyEnum::Struct => "",
+        //~^ ERROR expected unit struct/variant or constant, found struct variant `MyEnum::Struct`
+    };
+}
+
+fn main() {}

src/test/ui/issues/issue-63983.stderr

@@ -0,0 +1,15 @@
+error[E0532]: expected unit struct/variant or constant, found tuple variant `MyEnum::Tuple`
+  --> $DIR/issue-63983.rs:8:9
+   |
+LL |         MyEnum::Tuple => "",
+   |         ^^^^^^^^^^^^^ did you mean `MyEnum::Tuple ( /* fields */ )`?
+
+error[E0532]: expected unit struct/variant or constant, found struct variant `MyEnum::Struct`
+  --> $DIR/issue-63983.rs:10:9
+   |
+LL |         MyEnum::Struct => "",
+   |         ^^^^^^^^^^^^^^ did you mean `MyEnum::Struct { /* fields */ }`?
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0532`.