add lint declaration and example that should trigger the lint

clippy_lints/src/loops.rs

@@ -328,6 +328,14 @@ declare_lint! {
     "any loop that will always `break` or `return`"
 }
 
+/// TODO: add documentation
+
+declare_lint! {
+    pub MUT_RANGE_BOUND,
+    Warn,
+    "for loop over a range where one of the bounds is a mutable variable"
+}
+
 #[derive(Copy, Clone)]
 pub struct Pass;
 
@@ -348,7 +356,8 @@ impl LintPass for Pass {
             EMPTY_LOOP,
             WHILE_LET_ON_ITERATOR,
             FOR_KV_MAP,
-            NEVER_LOOP
+            NEVER_LOOP, 
+            MUT_RANGE_BOUND
         )
     }
 }

tests/run-pass/mut_range_bound.rs

@@ -0,0 +1,15 @@
+#![feature(plugin)]
+#![plugin(clippy)]
+
+// cause the build to fail if this warning is invoked
+#![deny(check_for_loop_mut_bound)]
+
+// an example
+fn mut_range_bound() {
+    let mut m = 4;
+    for i in 0..m { continue; } // ERROR One of the range bounds is mutable
+}
+
+fn main(){
+    mut_range_bound();
+}