100 lines
2.8 KiB
Rust
100 lines
2.8 KiB
Rust
use crate::utils::{match_def_path, match_trait_method, paths, span_lint};
|
|
use if_chain::if_chain;
|
|
use rustc_hir::{Expr, ExprKind, Item, ItemKind};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_session::{declare_tool_lint, impl_lint_pass};
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for uses of `to_string()` in `Display` traits.
|
|
///
|
|
/// **Why is this bad?** Usually `to_string` is implemented indirectly
|
|
/// via `Display`. Hence using it while implementing `Display` would
|
|
/// lead to infinite recursion.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// use std::fmt;
|
|
///
|
|
/// struct Structure(i32);
|
|
/// impl fmt::Display for Structure {
|
|
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
/// write!(f, "{}", self.to_string())
|
|
/// }
|
|
/// }
|
|
///
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// use std::fmt;
|
|
///
|
|
/// struct Structure(i32);
|
|
/// impl fmt::Display for Structure {
|
|
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
/// write!(f, "{}", self.0)
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
pub TO_STRING_IN_DISPLAY,
|
|
correctness,
|
|
"to_string method used while implementing Display trait"
|
|
}
|
|
|
|
#[derive(Default)]
|
|
pub struct ToStringInDisplay {
|
|
in_display_impl: bool,
|
|
}
|
|
|
|
impl ToStringInDisplay {
|
|
pub fn new() -> Self {
|
|
Self { in_display_impl: false }
|
|
}
|
|
}
|
|
|
|
impl_lint_pass!(ToStringInDisplay => [TO_STRING_IN_DISPLAY]);
|
|
|
|
impl LateLintPass<'_> for ToStringInDisplay {
|
|
fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
|
|
if is_display_impl(cx, item) {
|
|
self.in_display_impl = true;
|
|
}
|
|
}
|
|
|
|
fn check_item_post(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
|
|
if is_display_impl(cx, item) {
|
|
self.in_display_impl = false;
|
|
}
|
|
}
|
|
|
|
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
|
|
if_chain! {
|
|
if let ExprKind::MethodCall(ref path, _, _, _) = expr.kind;
|
|
if path.ident.name == sym!(to_string);
|
|
if match_trait_method(cx, expr, &paths::TO_STRING);
|
|
if self.in_display_impl;
|
|
|
|
then {
|
|
span_lint(
|
|
cx,
|
|
TO_STRING_IN_DISPLAY,
|
|
expr.span,
|
|
"Using to_string in fmt::Display implementation might lead to infinite recursion",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_display_impl(cx: &LateContext<'_>, item: &Item<'_>) -> bool {
|
|
if_chain! {
|
|
if let ItemKind::Impl { of_trait: Some(trait_ref), .. } = &item.kind;
|
|
if let Some(did) = trait_ref.trait_def_id();
|
|
then {
|
|
match_def_path(cx, did, &paths::DISPLAY_TRAIT)
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
}
|