auto merge of #13034 : edwardw/rust/match, r=nikomatsakis

The `_match.rs` takes advantage of passes prior to `trans` and
aggressively prunes the sub-match tree based on exact equality. When it
comes to literal or range, the strategy may lead to wrong result if
there's guard function or multiple patterns inside tuple.

Closes #12582.
Closes #13027.

src/test/run-pass/issue-12582.rs

@@ -0,0 +1,29 @@
+// Copyright 2012-2014 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.
+
+pub fn main() {
+    let x = 1;
+    let y = 2;
+
+    assert_eq!(3, match (x, y) {
+        (1, 1) => 1,
+        (2, 2) => 2,
+        (1..2, 2) => 3,
+        _ => 4,
+    });
+
+    // nested tuple
+    assert_eq!(3, match ((x, y),) {
+        ((1, 1),) => 1,
+        ((2, 2),) => 2,
+        ((1..2, 2),) => 3,
+        _ => 4,
+    });
+}

src/test/run-pass/issue-13027.rs

@@ -0,0 +1,170 @@
+// Copyright 2012-2014 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.
+
+// Tests that match expression handles overlapped literal and range
+// properly in the presence of guard function.
+
+fn val() -> uint { 1 }
+
+static CONST: uint = 1;
+
+pub fn main() {
+    lit_shadow_range();
+    range_shadow_lit();
+    range_shadow_range();
+    multi_pats_shadow_lit();
+    multi_pats_shadow_range();
+    lit_shadow_multi_pats();
+    range_shadow_multi_pats();
+}
+
+fn lit_shadow_range() {
+    assert_eq!(2, match 1 {
+        1 if false => 1,
+        1..2 => 2,
+        _ => 3
+    });
+
+    let x = 0;
+    assert_eq!(2, match x+1 {
+        0 => 0,
+        1 if false => 1,
+        1..2 => 2,
+        _ => 3
+    });
+
+    assert_eq!(2, match val() {
+        1 if false => 1,
+        1..2 => 2,
+        _ => 3
+    });
+
+    assert_eq!(2, match CONST {
+        0 => 0,
+        1 if false => 1,
+        1..2 => 2,
+        _ => 3
+    });
+
+    // value is out of the range of second arm, should match wildcard pattern
+    assert_eq!(3, match 3 {
+        1 if false => 1,
+        1..2 => 2,
+        _ => 3
+    });
+}
+
+fn range_shadow_lit() {
+    assert_eq!(2, match 1 {
+        1..2 if false => 1,
+        1 => 2,
+        _ => 3
+    });
+
+    let x = 0;
+    assert_eq!(2, match x+1 {
+        0 => 0,
+        1..2 if false => 1,
+        1 => 2,
+        _ => 3
+    });
+
+    assert_eq!(2, match val() {
+        1..2 if false => 1,
+        1 => 2,
+        _ => 3
+    });
+
+    assert_eq!(2, match CONST {
+        0 => 0,
+        1..2 if false => 1,
+        1 => 2,
+        _ => 3
+    });
+
+    // ditto
+    assert_eq!(3, match 3 {
+        1..2 if false => 1,
+        1 => 2,
+        _ => 3
+    });
+}
+
+fn range_shadow_range() {
+    assert_eq!(2, match 1 {
+        0..2 if false => 1,
+        1..3 => 2,
+        _ => 3,
+    });
+
+    let x = 0;
+    assert_eq!(2, match x+1 {
+        100 => 0,
+        0..2 if false => 1,
+        1..3 => 2,
+        _ => 3,
+    });
+
+    assert_eq!(2, match val() {
+        0..2 if false => 1,
+        1..3 => 2,
+        _ => 3,
+    });
+
+    assert_eq!(2, match CONST {
+        100 => 0,
+        0..2 if false => 1,
+        1..3 => 2,
+        _ => 3,
+    });
+
+    // ditto
+    assert_eq!(3, match 5 {
+        0..2 if false => 1,
+        1..3 => 2,
+        _ => 3,
+    });
+}
+
+fn multi_pats_shadow_lit() {
+    assert_eq!(2, match 1 {
+        100 => 0,
+        0 | 1..10 if false => 1,
+        1 => 2,
+        _ => 3,
+    });
+}
+
+fn multi_pats_shadow_range() {
+    assert_eq!(2, match 1 {
+        100 => 0,
+        0 | 1..10 if false => 1,
+        1..3 => 2,
+        _ => 3,
+    });
+}
+
+fn lit_shadow_multi_pats() {
+    assert_eq!(2, match 1 {
+        100 => 0,
+        1 if false => 1,
+        0 | 1..10 => 2,
+        _ => 3,
+    });
+}
+
+fn range_shadow_multi_pats() {
+    assert_eq!(2, match 1 {
+        100 => 0,
+        1..3 if false => 1,
+        0 | 1..10 => 2,
+        _ => 3,
+    });
+}