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Implement manual_and and manual_or lints
Suggests replacing if-else expressions where one branch is a boolean literal with && / || operators. Co-authored-by: Francisco Salgueiro <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,193 @@ | ||
| use clippy_utils::diagnostics::span_lint_and_sugg; | ||
| use clippy_utils::visitors::for_each_expr; | ||
| use clippy_utils::{get_parent_expr, higher, peel_blocks}; | ||
| use core::ops::ControlFlow; | ||
| use rustc_ast::ast::LitKind; | ||
| use rustc_ast::BinOpKind; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir::{Expr, ExprKind}; | ||
| use rustc_lint::{LateContext, LateLintPass, LintContext}; | ||
| use rustc_session::declare_lint_pass; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Detects `if`-then-`else` that can be replaced with `&&`. | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// `&&` is simpler than `if`-then-`else`. | ||
| /// | ||
| /// ### Example | ||
| /// ```ignore | ||
| /// if a { | ||
| /// b | ||
| /// } else { | ||
| /// false | ||
| /// } | ||
| /// ``` | ||
| /// Use instead: | ||
| /// ```ignore | ||
| /// a && b | ||
| /// ``` | ||
| #[clippy::version = "1.80.0"] | ||
| pub MANUAL_AND, | ||
| complexity, | ||
| "this `if`-then-`else` that can be replaced with `&&`." | ||
| } | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Detects `if`-then-`else` that can be replaced with `||`. | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// `||` is simpler than `if`-then-`else`. | ||
| /// | ||
| /// ### Example | ||
| /// ```ignore | ||
| /// if a { | ||
| /// true | ||
| /// } else { | ||
| /// b | ||
| /// } | ||
| /// ``` | ||
| /// Use instead: | ||
| /// ```ignore | ||
| /// a || b | ||
| /// ``` | ||
| #[clippy::version = "1.80.0"] | ||
| pub MANUAL_OR, | ||
| complexity, | ||
| "this `if`-then-`else` expression can be simplified with `||`" | ||
| } | ||
|
|
||
| declare_lint_pass!(ManualAndOr => [MANUAL_AND, MANUAL_OR]); | ||
|
|
||
| fn extract_final_expression_snippet<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<String> { | ||
| if let ExprKind::Block(block, _) = expr.kind { | ||
| if let Some(final_expr) = block.expr { | ||
| return cx.sess().source_map().span_to_snippet(final_expr.span).ok(); | ||
| } | ||
| } | ||
| cx.sess().source_map().span_to_snippet(expr.span).ok() | ||
| } | ||
|
|
||
| fn fetch_bool_expr(expr: &Expr<'_>) -> Option<bool> { | ||
| if let ExprKind::Lit(lit_ptr) = peel_blocks(expr).kind { | ||
| if let LitKind::Bool(value) = lit_ptr.node { | ||
| return Some(value); | ||
| } | ||
| } | ||
| None | ||
| } | ||
|
|
||
| fn contains_let(cond: &Expr<'_>) -> bool { | ||
| for_each_expr(cond, |e| { | ||
| if matches!(e.kind, ExprKind::Let(_)) { | ||
| ControlFlow::Break(()) | ||
| } else { | ||
| ControlFlow::Continue(()) | ||
| } | ||
| }) | ||
| .is_some() | ||
| } | ||
|
|
||
| fn contains_or(cond: &Expr<'_>) -> bool { | ||
| for_each_expr(cond, |e| { | ||
| if let ExprKind::Binary(ref n, _, _) = e.kind { | ||
| if n.node == BinOpKind::Or { | ||
| ControlFlow::Break(()) | ||
| } else { | ||
| ControlFlow::Continue(()) | ||
| } | ||
| } else { | ||
| ControlFlow::Continue(()) | ||
| } | ||
| }) | ||
| .is_some() | ||
| } | ||
|
|
||
| fn check_and<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>, cond: &Expr<'tcx>, then: &Expr<'tcx>) { | ||
| if let Some(parent) = get_parent_expr(cx, expr) { | ||
| if let ExprKind::If(_, _, _) = parent.kind { | ||
| return; | ||
| } | ||
| } | ||
| if contains_or(cond) || contains_or(then) || fetch_bool_expr(then).is_some() { | ||
| return; | ||
| } | ||
| if match then.kind { | ||
| ExprKind::Block(block, _) => !block.stmts.is_empty(), | ||
| _ => false, | ||
| } { | ||
| return; | ||
| } | ||
|
|
||
| let applicability = Applicability::MachineApplicable; | ||
| let cond_snippet = cx | ||
| .sess() | ||
| .source_map() | ||
| .span_to_snippet(cond.span) | ||
| .unwrap_or_else(|_| "..".to_string()); | ||
|
|
||
| let then_snippet = extract_final_expression_snippet(cx, then).unwrap_or_else(|| "..".to_string()); | ||
| let suggestion = format!("{cond_snippet} && {then_snippet}"); | ||
| span_lint_and_sugg( | ||
| cx, | ||
| MANUAL_AND, | ||
| expr.span, | ||
| "this `if`-then-`else` expression can be simplified with `&&`", | ||
| "try", | ||
| suggestion, | ||
| applicability, | ||
| ); | ||
| } | ||
|
|
||
| fn check_or<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>, cond: &Expr<'tcx>, else_expr: &Expr<'tcx>) { | ||
| if matches!(else_expr.kind, ExprKind::If(..)) || fetch_bool_expr(else_expr).is_some() { | ||
| return; | ||
| } | ||
| if match else_expr.kind { | ||
| ExprKind::Block(block, _) => !block.stmts.is_empty(), | ||
| _ => false, | ||
| } { | ||
| return; | ||
| } | ||
|
|
||
| let applicability = Applicability::MachineApplicable; | ||
| let cond_snippet = cx | ||
| .sess() | ||
| .source_map() | ||
| .span_to_snippet(cond.span) | ||
| .unwrap_or_else(|_| "..".to_string()); | ||
|
|
||
| let else_snippet = extract_final_expression_snippet(cx, else_expr).unwrap_or_else(|| "..".to_string()); | ||
| let suggestion = format!("{cond_snippet} || {else_snippet}"); | ||
| span_lint_and_sugg( | ||
| cx, | ||
| MANUAL_OR, | ||
| expr.span, | ||
| "this `if`-then-`else` expression can be simplified with `||`", | ||
| "try", | ||
| suggestion, | ||
| applicability, | ||
| ); | ||
| } | ||
|
|
||
| impl<'tcx> LateLintPass<'tcx> for ManualAndOr { | ||
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) { | ||
| if let Some(higher::If { | ||
| cond, | ||
| then, | ||
| r#else: Some(else_expr), | ||
| }) = higher::If::hir(expr) | ||
| { | ||
| if contains_let(cond) { | ||
| return; | ||
| } | ||
| if let Some(false) = fetch_bool_expr(else_expr) { | ||
| check_and(cx, expr, cond, then); | ||
| } else if let Some(true) = fetch_bool_expr(then) { | ||
| check_or(cx, expr, cond, else_expr); | ||
| } | ||
| } | ||
| } | ||
| } |
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