use crate::utils::usage::{is_unused, mutated_variables};
use crate::utils::{
contains_name, get_enclosing_block, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
- indent_of, is_integer_const, is_no_std_crate, is_refutable, is_type_diagnostic_item, last_path_segment,
- match_trait_method, match_type, match_var, multispan_sugg, qpath_res, single_segment_path, snippet,
- snippet_with_applicability, snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg,
- span_lint_and_then, sugg, SpanlessEq,
+ indent_of, is_in_panic_handler, is_integer_const, is_no_std_crate, is_refutable, is_type_diagnostic_item,
+ last_path_segment, match_trait_method, match_type, match_var, multispan_sugg, qpath_res, single_segment_path,
+ snippet, snippet_with_applicability, snippet_with_macro_callsite, span_lint, span_lint_and_help,
+ span_lint_and_sugg, span_lint_and_then, sugg, SpanlessEq,
};
use if_chain::if_chain;
use rustc_ast::ast;
// (also matches an explicit "match" instead of "if let")
// (even if the "match" or "if let" is used for declaration)
if let ExprKind::Loop(ref block, _, LoopSource::Loop) = expr.kind {
- // also check for empty `loop {}` statements
- // TODO(issue #6161): Enable for no_std crates (outside of #[panic_handler])
- if block.stmts.is_empty() && block.expr.is_none() && !is_no_std_crate(cx.tcx.hir().krate()) {
- span_lint_and_help(
- cx,
- EMPTY_LOOP,
- expr.span,
- "empty `loop {}` wastes CPU cycles",
- None,
- "You should either use `panic!()` or add `std::thread::sleep(..);` to the loop body.",
- );
+ // also check for empty `loop {}` statements, skipping those in #[panic_handler]
+ if block.stmts.is_empty() && 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.tcx.hir().krate()) {
+ "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);
}
// extract the expression from the first statement (if any) in a block