1 use clippy_utils::diagnostics::span_lint_and_help;
2 use clippy_utils::source::snippet;
3 use clippy_utils::{is_entrypoint_fn, is_no_std_crate};
4 use if_chain::if_chain;
5 use rustc_hir::{Crate, Expr, ExprKind, QPath};
6 use rustc_lint::{LateContext, LateLintPass};
7 use rustc_session::{declare_tool_lint, impl_lint_pass};
11 /// Checks for recursion using the entrypoint.
13 /// ### Why is this bad?
14 /// Apart from special setups (which we could detect following attributes like #![no_std]),
15 /// recursing into main() seems like an unintuitive antipattern we should be able to detect.
25 "recursion using the entrypoint"
29 pub struct MainRecursion {
30 has_no_std_attr: bool,
33 impl_lint_pass!(MainRecursion => [MAIN_RECURSION]);
35 impl LateLintPass<'_> for MainRecursion {
36 fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
37 self.has_no_std_attr = is_no_std_crate(cx);
40 fn check_expr_post(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
41 if self.has_no_std_attr {
46 if let ExprKind::Call(func, _) = &expr.kind;
47 if let ExprKind::Path(QPath::Resolved(_, path)) = &func.kind;
48 if let Some(def_id) = path.res.opt_def_id();
49 if is_entrypoint_fn(cx, def_id);
55 &format!("recursing into entrypoint `{}`", snippet(cx, func.span, "main")),
57 "consider using another function for this recursion"