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use rustc_hir::{Crate, Expr, ExprKind, QPath};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use crate::utils::{is_entrypoint_fn, is_no_std_crate, snippet, span_lint_and_help};
use if_chain::if_chain;
declare_clippy_lint! {
/// **What it does:** Checks for recursion using the entrypoint.
///
/// **Why is this bad?** Apart from special setups (which we could detect following attributes like #![no_std]),
/// recursing into main() seems like an unintuitive antipattern we should be able to detect.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```no_run
/// fn main() {
/// main();
/// }
/// ```
pub MAIN_RECURSION,
style,
"recursion using the entrypoint"
}
#[derive(Default)]
pub struct MainRecursion {
has_no_std_attr: bool,
}
impl_lint_pass!(MainRecursion => [MAIN_RECURSION]);
impl LateLintPass<'_, '_> for MainRecursion {
fn check_crate(&mut self, _: &LateContext<'_, '_>, krate: &Crate<'_>) {
self.has_no_std_attr = is_no_std_crate(krate);
}
fn check_expr_post(&mut self, cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
if self.has_no_std_attr {
return;
}
if_chain! {
if let ExprKind::Call(func, _) = &expr.kind;
if let ExprKind::Path(path) = &func.kind;
if let QPath::Resolved(_, path) = &path;
if let Some(def_id) = path.res.opt_def_id();
if is_entrypoint_fn(cx, def_id);
then {
span_lint_and_help(
cx,
MAIN_RECURSION,
func.span,
&format!("recursing into entrypoint `{}`", snippet(cx, func.span, "main")),
"consider using another function for this recursion"
)
}
}
}
}
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