be more robust to bogus items in struct patterns/constructors

Fixes #27815

src/test/compile-fail-fulldeps/issue-18986.rs

@@ -15,6 +15,6 @@ pub use use_from_trait_xc::Trait;
 
 fn main() {
     match () {
-        Trait { x: 42 } => () //~ ERROR use of trait `Trait` in a struct pattern
+        Trait { x: 42 } => () //~ ERROR `Trait` does not name a struct
     }
 }

src/test/compile-fail/issue-27815.rs

@@ -0,0 +1,20 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod A {}
+
+fn main() {
+    let u = A { x: 1 }; //~ ERROR `A` does not name a structure
+    let v = u32 { x: 1 }; //~ ERROR `u32` does not name a structure
+    match () {
+        A { x: 1 } => {} //~ ERROR `A` does not name a struct
+        u32 { x: 1 } => {} //~ ERROR `u32` does not name a struct
+    }
+}

src/test/compile-fail/trait-as-struct-constructor.rs

@@ -12,5 +12,5 @@ trait TraitNotAStruct {}
 
 fn main() {
     TraitNotAStruct{ value: 0 };
-    //~^ ERROR: use of trait `TraitNotAStruct` as a struct constructor [E0159]
+    //~^ ERROR: `TraitNotAStruct` does not name a structure [E0071]
 }