Provide a witness pattern for non-exhaustive patterns

Fixed #4321

src/test/compile-fail/issue-2111.rs

@@ -9,7 +9,8 @@
 // except according to those terms.
 
 fn foo(a: Option<uint>, b: Option<uint>) {
-  match (a,b) { //~ ERROR: non-exhaustive patterns: None not covered
+  match (a,b) {
+  //~^ ERROR: non-exhaustive patterns: (core::option::None, core::option::None) not covered
     (Some(a), Some(b)) if a == b => { }
     (Some(_), None) |
     (None, Some(_)) => { }

src/test/compile-fail/issue-4321.rs

@@ -0,0 +1,18 @@
+// Copyright 2014 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.
+
+fn main() {
+    let tup = (true, true);
+    println!("foo {:}", match tup { //~ ERROR non-exhaustive patterns: (true, false) not covered
+        (false, false) => "foo",
+        (false, true) => "bar",
+        (true, true) => "baz"
+    });
+}

src/test/compile-fail/non-exhaustive-match-nested.rs

@@ -8,13 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern: non-exhaustive patterns
 enum t { a(u), b }
 enum u { c, d }
 
 fn main() {
   let x = a(c);
-  match x {
+  match x { //~ ERROR non-exhaustive patterns: a(c) not covered
       a(d) => { fail!("hello"); }
       b => { fail!("goodbye"); }
     }

src/test/compile-fail/non-exhaustive-match.rs

@@ -12,21 +12,21 @@ enum t { a, b, }
 
 fn main() {
     let x = a;
-    match x { b => { } } //~ ERROR non-exhaustive patterns
+    match x { b => { } } //~ ERROR non-exhaustive patterns: a not covered
-    match true { //~ ERROR non-exhaustive patterns
+    match true { //~ ERROR non-exhaustive patterns: false not covered
       true => {}
     }
-    match Some(10) { //~ ERROR non-exhaustive patterns
+    match Some(10) { //~ ERROR non-exhaustive patterns: core::option::Some(_) not covered
       None => {}
     }
-    match (2, 3, 4) { //~ ERROR non-exhaustive patterns
+    match (2, 3, 4) { //~ ERROR non-exhaustive patterns: (_, _, _) not covered
       (_, _, 4) => {}
     }
-    match (a, a) { //~ ERROR non-exhaustive patterns
+    match (a, a) { //~ ERROR non-exhaustive patterns: (a, a) not covered
       (a, b) => {}
       (b, a) => {}
     }
-    match a { //~ ERROR b not covered
+    match a { //~ ERROR non-exhaustive patterns: b not covered
       a => {}
     }
     // This is exhaustive, though the algorithm got it wrong at one point
@@ -37,8 +37,7 @@ fn main() {
     }
     let vec = vec!(Some(42), None, Some(21));
     let vec: &[Option<int>] = vec.as_slice();
-    match vec {
+    match vec { //~ ERROR non-exhaustive patterns: [] not covered
-        //~^ ERROR non-exhaustive patterns: vectors of length 0 not covered
         [Some(..), None, ..tail] => {}
         [Some(..), Some(..), ..tail] => {}
         [None] => {}
@@ -51,7 +50,7 @@ fn main() {
     }
     let vec = vec!(0.5);
     let vec: &[f32] = vec.as_slice();
-    match vec { //~ ERROR non-exhaustive patterns: vectors of length 4 not covered
+    match vec { //~ ERROR non-exhaustive patterns: [_, _, _, _] not covered
         [0.1, 0.2, 0.3] => (),
         [0.1, 0.2] => (),
         [0.1] => (),

src/test/compile-fail/refutable-pattern-errors.rs

@@ -10,9 +10,9 @@
 
 
 fn func((1, (Some(1), 2..3)): (int, (Option<int>, int))) { }
-//~^ ERROR refutable pattern in function argument
+//~^ ERROR refutable pattern in function argument: (_, _) not covered
 
 fn main() {
     let (1, (Some(1), 2..3)) = (1, (None, 2));
-    //~^ ERROR refutable pattern in local binding
+    //~^ ERROR refutable pattern in local binding: (_, _) not covered
 }

src/test/compile-fail/refutable-pattern-in-fn-arg.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 fn main() {
-    let f = |3: int| println!("hello");  //~ ERROR refutable pattern
+    let f = |3: int| println!("hello");
+    //~^ ERROR refutable pattern in function argument: _ not covered
     f(4);
 }