new lint to detect

README.md

@@ -20,6 +20,7 @@ name
 [cmp_nan](https://github.com/Manishearth/rust-clippy/wiki#cmp_nan)                                     | deny    | comparisons to NAN (which will always return false, which is probably not intended)
 [cmp_owned](https://github.com/Manishearth/rust-clippy/wiki#cmp_owned)                                 | warn    | creating owned instances for comparing with others, e.g. `x == "foo".to_string()`
 [collapsible_if](https://github.com/Manishearth/rust-clippy/wiki#collapsible_if)                       | warn    | two nested `if`-expressions can be collapsed into one, e.g. `if x { if y { foo() } }` can be written as `if x && y { foo() }`
+[empty_loop](https://github.com/Manishearth/rust-clippy/wiki#empty_loop)                               | warn    | empty `loop {}` detected
 [eq_op](https://github.com/Manishearth/rust-clippy/wiki#eq_op)                                         | warn    | equal operands on both sides of a comparison or bitwise combination (e.g. `x == x`)
 [explicit_counter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_counter_loop)         | warn    | for-looping with an explicit counter when `_.enumerate()` would do
 [explicit_iter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_iter_loop)               | warn    | for-looping over `_.iter()` or `_.iter_mut()` when `&_` or `&mut _` would do

src/lib.rs

@@ -122,6 +122,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
         len_zero::LEN_WITHOUT_IS_EMPTY,
         len_zero::LEN_ZERO,
         lifetimes::NEEDLESS_LIFETIMES,
+        loops::EMPTY_LOOP,
         loops::EXPLICIT_COUNTER_LOOP,
         loops::EXPLICIT_ITER_LOOP,
         loops::ITER_NEXT_LOOP,

src/loops.rs

@@ -36,13 +36,16 @@ declare_lint!{ pub REVERSE_RANGE_LOOP, Warn,
 declare_lint!{ pub EXPLICIT_COUNTER_LOOP, Warn,
                "for-looping with an explicit counter when `_.enumerate()` would do" }
 
+declare_lint!{ pub EMPTY_LOOP, Warn, "empty `loop {}` detected" }
+
 #[derive(Copy, Clone)]
 pub struct LoopsPass;
 
 impl LintPass for LoopsPass {
     fn get_lints(&self) -> LintArray {
         lint_array!(NEEDLESS_RANGE_LOOP, EXPLICIT_ITER_LOOP, ITER_NEXT_LOOP,
-                    WHILE_LET_LOOP, UNUSED_COLLECT, REVERSE_RANGE_LOOP, EXPLICIT_COUNTER_LOOP)
+                    WHILE_LET_LOOP, UNUSED_COLLECT, REVERSE_RANGE_LOOP, 
+                    EXPLICIT_COUNTER_LOOP, EMPTY_LOOP)
     }
 }
 
@@ -163,6 +166,14 @@ impl LateLintPass for LoopsPass {
         // (also matches an explicit "match" instead of "if let")
         // (even if the "match" or "if let" is used for declaration)
         if let ExprLoop(ref block, _) = expr.node {
+            // also check for empty `loop {}` statements
+            if block.stmts.is_empty() && block.expr.is_none() {
+                span_lint(cx, EMPTY_LOOP, expr.span,
+                          "empty `loop {}` detected. You may want to either \
+                           use `panic!()` or add `std::thread::sleep(..);` to \
+                           the loop body.");
+            }
+            
             // extract the first statement (if any) in a block
             let inner_stmt = extract_expr_from_first_stmt(block);
             // extract a single expression

tests/compile-fail/while_loop.rs

@@ -1,7 +1,7 @@
 #![feature(plugin)]
 #![plugin(clippy)]
 
-#![deny(while_let_loop)]
+#![deny(while_let_loop, empty_loop)]
 #![allow(dead_code, unused)]
 
 fn main() {
@@ -58,6 +58,6 @@ fn no_panic<T>(slice: &[T]) {
             Some(ele) => ele,
             None => break
         };
-        loop {}
+        loop {} //~ERROR empty `loop {}` detected.
     }
 }