Add new lint: non_uppercase_pattern_statics, for #7526.

This tries to warn about code like:
    ```rust
    match (0,0) {
        (0, aha) => { ... },
        ...
    }
    ```
where `aha` is actually a static constant, not a binding.

src/test/compile-fail/match-static-const-lc.rs

@@ -0,0 +1,43 @@
+// Copyright 2012-2013 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.
+
+// Issue #7526: lowercase static constants in patterns look like bindings
+
+#[deny(non_uppercase_pattern_statics)];
+
+pub static a : int = 97;
+
+fn f() {
+    let r = match (0,0) {
+        (0, a) => 0,
+        //~^ ERROR static constant in pattern should have an uppercase id
+        (x, y) => 1 + x + y,
+    };
+    assert!(r == 1);
+}
+
+mod m {
+    pub static aha : int = 7;
+}
+
+fn g() {
+    use m::aha;
+    let r = match (0,0) {
+        (0, aha) => 0,
+        //~^ ERROR static constant in pattern should have an uppercase id
+        (x, y)   => 1 + x + y,
+    };
+    assert!(r == 1);
+}
+
+fn main () {
+    f();
+    g();
+}

src/test/run-pass/match-static-const-rename.rs

@@ -0,0 +1,47 @@
+// Copyright 2012-2013 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.
+
+// Issue #7526: lowercase static constants in patterns look like bindings
+
+// This is similar to compile-fail/match-static-const-lc, except it
+// shows the expected usual workaround (choosing a different name for
+// the static definition) and also demonstrates that one can work
+// around this problem locally by reanming the constant in the `use`
+// form to an uppercase identifier that placates the lint.
+
+#[deny(non_uppercase_pattern_statics)];
+
+pub static A : int = 97;
+
+fn f() {
+    let r = match (0,0) {
+        (0, A) => 0,
+        (x, y) => 1 + x + y,
+    };
+    assert!(r == 1);
+}
+
+mod m {
+    pub static aha : int = 7;
+}
+
+fn g() {
+    use AHA = m::aha;
+    let r = match (0,0) {
+        (0, AHA) => 0,
+        (x, y)   => 1 + x + y,
+    };
+    assert!(r == 1);
+}
+
+fn main () {
+    f();
+    g();
+}