New upstream version 1.52.1+dfsg1

[rustc.git] / src / tools / clippy / clippy_lints / src / loops / empty_loop.rs

diff --git a/src/tools/clippy/clippy_lints/src/loops/empty_loop.rs b/src/tools/clippy/clippy_lints/src/loops/empty_loop.rs
new file mode 100644 (file)
index 0000000..43e8553
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/loops/empty_loop.rs
@@ -0,0 +1,17 @@
+use super::EMPTY_LOOP;
+use crate::utils::{is_in_panic_handler, is_no_std_crate, span_lint_and_help};
+
+use rustc_hir::{Block, Expr};
+use rustc_lint::LateContext;
+
+pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, loop_block: &'tcx Block<'_>) {
+    if loop_block.stmts.is_empty() && loop_block.expr.is_none() && !is_in_panic_handler(cx, expr) {
+        let msg = "empty `loop {}` wastes CPU cycles";
+        let help = if is_no_std_crate(cx) {
+            "you should either use `panic!()` or add a call pausing or sleeping the thread to the loop body"
+        } else {
+            "you should either use `panic!()` or add `std::thread::sleep(..);` to the loop body"
+        };
+        span_lint_and_help(cx, EMPTY_LOOP, expr.span, msg, None, help);
+    }
+}