Add some more tests

Author: petrochenkov

src/doc/reference.md

@@ -1178,11 +1178,20 @@ let px: i32 = match p { Point(x, _) => x };
 ```
 
 A _unit-like struct_ is a structure without any fields, defined by leaving off
-the list of fields entirely. Such types will have a single value. For example:
+the list of fields entirely. Such structure implicitly defines a constant of
+its type with the same name. For example:
 
 ```
 struct Cookie;
-let c = [Cookie, Cookie, Cookie, Cookie];
+let c = [Cookie, Cookie {}, Cookie, Cookie {}];
+```
+
+is equivalent to
+
+```
+struct Cookie {}
+const Cookie: Cookie = Cookie {};
+let c = [Cookie, Cookie {}, Cookie, Cookie {}];
 ```
 
 The precise memory layout of a structure is not specified. One can specify a

src/test/run-pass/empty-struct-with-braces.rs

@@ -13,11 +13,15 @@
 
 struct Empty1 {}
 struct Empty2;
+struct Empty3 {}
+const Empty3: Empty3 = Empty3 {};
 
 fn main() {
     let e1: Empty1 = Empty1 {};
     let e2: Empty2 = Empty2 {};
     let e2: Empty2 = Empty2;
+    let e3: Empty3 = Empty3 {};
+    let e3: Empty3 = Empty3;
 
     match e1 {
         Empty1 {} => ()
@@ -28,4 +32,23 @@ fn main() {
     match e2 {
         Empty2 => ()
     }
+    match e3 {
+        Empty3 {} => ()
+    }
+    match e3 {
+        Empty3 => ()
+    }
+    match e1 {
+        Empty1 { .. } => ()
+    }
+    match e2 {
+        Empty2 { .. } => ()
+    }
+    match e3 {
+        Empty3 { .. } => ()
+    }
+
+    let e11 = Empty1 { ..e1 };
+    let e22 = Empty2 { ..e2 };
+    let e33 = Empty3 { ..e3 };
 }