do not suggest enum tuple variant for named field variant

compiler/rustc_typeck/src/check/demand.rs

@@ -336,7 +336,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let compatible_variants: Vec<String> = expected_adt
                 .variants()
                 .iter()
-                .filter(|variant| variant.fields.len() == 1)
+                .filter(|variant| {
+                    variant.fields.len() == 1 && variant.ctor_kind == hir::def::CtorKind::Fn
+                })
                 .filter_map(|variant| {
                     let sole_field = &variant.fields[0];
                     let sole_field_ty = sole_field.ty(self.tcx, substs);

src/test/ui/did_you_mean/compatible-variants.rs

@@ -64,3 +64,18 @@ fn main() {
     //~^ ERROR mismatched types
     //~| HELP try wrapping
 }
+
+enum A {
+    B { b: B},
+}
+
+enum B {
+    Fst,
+    Snd,
+}
+
+fn foo() {
+    // We don't want to suggest `A::B(B::Fst)` here.
+    let a: A = B::Fst;
+    //~^ ERROR mismatched types
+}

src/test/ui/did_you_mean/compatible-variants.stderr

@@ -190,6 +190,14 @@ help: try wrapping the expression in `Some`
 LL |     let _ = Foo { bar: Some(bar) };
    |                   ++++++++++   +
 
-error: aborting due to 11 previous errors
+error[E0308]: mismatched types
+  --> $DIR/compatible-variants.rs:79:16
+   |
+LL |     let a: A = B::Fst;
+   |            -   ^^^^^^ expected enum `A`, found enum `B`
+   |            |
+   |            expected due to this
+
+error: aborting due to 12 previous errors
 
 For more information about this error, try `rustc --explain E0308`.