auto merge of #10018 : fhahn/rust/check-inferred-ints, r=alexcrichton

I've started working on this issue and pushed a small commit, which adds a range check for integer literals in `middle::const_eval` (no `uint` at the moment) 
At the moment, this patch is just a proof of concept, I'm not sure if there is a better function for the checks in `middle::const_eval`. This patch does not check for overflows after constant folding, eg:

    let x: i8 = 99 + 99;

src/test/compile-fail/lint-type-limits.rs

@@ -24,11 +24,13 @@ fn bar() -> i8 {
 
 fn baz() -> bool {
     128 > bar() //~ ERROR comparison is useless due to type limits
+                //~^ WARNING literal out of range for its type
 }
 
 fn qux() {
     let mut i = 1i8;
     while 200 != i { //~ ERROR comparison is useless due to type limits
+                     //~^ WARNING literal out of range for its type
         i += 1;
     }
 }

src/test/compile-fail/lint-type-overflow.rs

@@ -0,0 +1,50 @@
+// Copyright 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.
+//
+
+#[deny(type_overflow)];
+
+fn test(x: i8) {
+    println!("x {}", x);
+}
+
+#[allow(unused_variable)]
+fn main() {
+    let x1: u8 = 255; // should be OK
+    let x1: u8 = 256; //~ error: literal out of range for its type
+
+    let x1 = 255_u8; // should be OK
+    let x1 = 256_u8; //~ error: literal out of range for its type
+
+    let x2: i8 = -128; // should be OK
+    let x1: i8 = 128; //~ error: literal out of range for its type
+    let x2: i8 = --128; //~ error: literal out of range for its type
+
+    let x3: i8 = -129; //~ error: literal out of range for its type
+    let x3: i8 = -(129); //~ error: literal out of range for its type
+    let x3: i8 = -{129}; //~ error: literal out of range for its type
+
+    test(1000); //~ error: literal out of range for its type
+
+    let x = 128_i8; //~ error: literal out of range for its type
+    let x = 127_i8; 
+    let x = -128_i8; 
+    let x = -(128_i8); 
+    let x = -129_i8; //~ error: literal out of range for its type
+
+    let x: i32 = 2147483647; // should be OK
+    let x = 2147483647_i32; // should be OK
+    let x: i32 = 2147483648; //~ error: literal out of range for its type
+    let x = 2147483648_i32; //~ error: literal out of range for its type
+    let x: i32 = -2147483648; // should be OK
+    let x = -2147483648_i32; // should be OK
+    let x: i32 = -2147483649; //~ error: literal out of range for its type
+    let x = -2147483649_i32; //~ error: literal out of range for its type
+}

src/test/compile-fail/oversized-literal.rs

@@ -8,6 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern:literal out of range
+// compile-flags: -D type-overflow
 
-fn main() { info!("{}", 300u8); }
+fn main() { info!("{}", 300u8); } //~ error: literal out of range for its type