107 lines
3.5 KiB
Rust
107 lines
3.5 KiB
Rust
use clippy_utils::macros::{find_assert_eq_args, root_macro_call_first_node};
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use clippy_utils::{diagnostics::span_lint_and_sugg, ty::implements_trait};
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use rustc_ast::ast::LitKind;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, Lit};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::symbol::Ident;
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declare_clippy_lint! {
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/// ### What it does
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/// This lint warns about boolean comparisons in assert-like macros.
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///
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/// ### Why is this bad?
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/// It is shorter to use the equivalent.
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///
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/// ### Example
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/// ```rust
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/// // Bad
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/// assert_eq!("a".is_empty(), false);
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/// assert_ne!("a".is_empty(), true);
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///
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/// // Good
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/// assert!(!"a".is_empty());
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/// ```
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#[clippy::version = "1.53.0"]
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pub BOOL_ASSERT_COMPARISON,
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style,
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"Using a boolean as comparison value in an assert_* macro when there is no need"
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}
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declare_lint_pass!(BoolAssertComparison => [BOOL_ASSERT_COMPARISON]);
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fn is_bool_lit(e: &Expr<'_>) -> bool {
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matches!(
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e.kind,
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ExprKind::Lit(Lit {
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node: LitKind::Bool(_),
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..
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})
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) && !e.span.from_expansion()
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}
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fn is_impl_not_trait_with_bool_out(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
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let ty = cx.typeck_results().expr_ty(e);
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cx.tcx
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.lang_items()
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.not_trait()
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.filter(|trait_id| implements_trait(cx, ty, *trait_id, &[]))
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.and_then(|trait_id| {
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cx.tcx.associated_items(trait_id).find_by_name_and_kind(
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cx.tcx,
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Ident::from_str("Output"),
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ty::AssocKind::Type,
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trait_id,
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)
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})
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.map_or(false, |assoc_item| {
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let proj = cx.tcx.mk_projection(assoc_item.def_id, cx.tcx.mk_substs_trait(ty, &[]));
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let nty = cx.tcx.normalize_erasing_regions(cx.param_env, proj);
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nty.is_bool()
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})
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}
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impl<'tcx> LateLintPass<'tcx> for BoolAssertComparison {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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let Some(macro_call) = root_macro_call_first_node(cx, expr) else { return };
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let macro_name = cx.tcx.item_name(macro_call.def_id);
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if !matches!(
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macro_name.as_str(),
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"assert_eq" | "debug_assert_eq" | "assert_ne" | "debug_assert_ne"
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) {
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return;
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}
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let Some ((a, b, _)) = find_assert_eq_args(cx, expr, macro_call.expn) else { return };
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if !(is_bool_lit(a) ^ is_bool_lit(b)) {
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// If there are two boolean arguments, we definitely don't understand
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// what's going on, so better leave things as is...
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//
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// Or there is simply no boolean and then we can leave things as is!
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return;
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}
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if !is_impl_not_trait_with_bool_out(cx, a) || !is_impl_not_trait_with_bool_out(cx, b) {
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// At this point the expression which is not a boolean
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// literal does not implement Not trait with a bool output,
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// so we cannot suggest to rewrite our code
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return;
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}
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let macro_name = macro_name.as_str();
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let non_eq_mac = ¯o_name[..macro_name.len() - 3];
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span_lint_and_sugg(
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cx,
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BOOL_ASSERT_COMPARISON,
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macro_call.span,
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&format!("used `{}!` with a literal bool", macro_name),
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"replace it with",
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format!("{}!(..)", non_eq_mac),
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Applicability::MaybeIncorrect,
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);
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}
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}
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