From 564cb87e270f70310e25ae9f459c642e949e8213 Mon Sep 17 00:00:00 2001
From: Takayuki Maeda <takoyaki0316@gmail.com>
Date: Mon, 27 Sep 2021 16:28:38 +0900
Subject: [PATCH] suggest path for tuple struct

---
 .../rustc_resolve/src/late/diagnostics.rs     |  8 +++++-
 .../resolve/suggest-path-for-tuple-struct.rs  | 26 +++++++++++++++++++
 .../suggest-path-for-tuple-struct.stderr      | 19 ++++++++++++++
 3 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/resolve/suggest-path-for-tuple-struct.rs
 create mode 100644 src/test/ui/resolve/suggest-path-for-tuple-struct.stderr

diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 19136c6ceeb..84219873d55 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/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);
diff --git a/src/test/ui/resolve/suggest-path-for-tuple-struct.rs b/src/test/ui/resolve/suggest-path-for-tuple-struct.rs
new file mode 100644
index 00000000000..c8bc3e79fe2
--- /dev/null
+++ b/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`
+}
diff --git a/src/test/ui/resolve/suggest-path-for-tuple-struct.stderr b/src/test/ui/resolve/suggest-path-for-tuple-struct.stderr
new file mode 100644
index 00000000000..957045ca74b
--- /dev/null
+++ b/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`.