use clippy_config::Conf; use clippy_config::msrvs::{self, Msrv}; use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then}; use clippy_utils::eq_expr_value; use clippy_utils::source::SpanRangeExt; use clippy_utils::ty::{implements_trait, is_type_diagnostic_item}; use rustc_ast::ast::LitKind; use rustc_errors::Applicability; use rustc_hir::intravisit::{FnKind, Visitor, walk_expr}; use rustc_hir::{BinOpKind, Body, Expr, ExprKind, FnDecl, UnOp}; use rustc_lint::{LateContext, LateLintPass, Level}; use rustc_session::{RustcVersion, impl_lint_pass}; use rustc_span::def_id::LocalDefId; use rustc_span::{Span, sym}; declare_clippy_lint! { /// ### What it does /// Checks for boolean expressions that can be written more /// concisely. /// /// ### Why is this bad? /// Readability of boolean expressions suffers from /// unnecessary duplication. /// /// ### Known problems /// Ignores short circuiting behavior of `||` and /// `&&`. Ignores `|`, `&` and `^`. /// /// ### Example /// ```ignore /// if a && true {} /// if !(a == b) {} /// ``` /// /// Use instead: /// ```rust,ignore /// if a {} /// if a != b {} /// ``` #[clippy::version = "pre 1.29.0"] pub NONMINIMAL_BOOL, complexity, "boolean expressions that can be written more concisely" } declare_clippy_lint! { /// ### What it does /// Checks for boolean expressions that contain terminals that /// can be eliminated. /// /// ### Why is this bad? /// This is most likely a logic bug. /// /// ### Known problems /// Ignores short circuiting behavior. /// /// ### Example /// ```rust,ignore /// // The `b` is unnecessary, the expression is equivalent to `if a`. /// if a && b || a { ... } /// ``` /// /// Use instead: /// ```rust,ignore /// if a {} /// ``` #[clippy::version = "pre 1.29.0"] pub OVERLY_COMPLEX_BOOL_EXPR, correctness, "boolean expressions that contain terminals which can be eliminated" } // For each pairs, both orders are considered. const METHODS_WITH_NEGATION: [(Option, &str, &str); 3] = [ (None, "is_some", "is_none"), (None, "is_err", "is_ok"), (Some(msrvs::IS_NONE_OR), "is_some_and", "is_none_or"), ]; pub struct NonminimalBool { msrv: Msrv, } impl NonminimalBool { pub fn new(conf: &'static Conf) -> Self { Self { msrv: conf.msrv.clone(), } } } impl_lint_pass!(NonminimalBool => [NONMINIMAL_BOOL, OVERLY_COMPLEX_BOOL_EXPR]); impl<'tcx> LateLintPass<'tcx> for NonminimalBool { fn check_fn( &mut self, cx: &LateContext<'tcx>, _: FnKind<'tcx>, _: &'tcx FnDecl<'_>, body: &'tcx Body<'_>, _: Span, _: LocalDefId, ) { NonminimalBoolVisitor { cx, msrv: &self.msrv }.visit_body(body); } fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) { match expr.kind { // This check the case where an element in a boolean comparison is inverted, like: // // ``` // let a = true; // !a == false; // ``` ExprKind::Binary(op, left, right) if matches!(op.node, BinOpKind::Eq | BinOpKind::Ne) => { check_inverted_bool_in_condition(cx, expr.span, op.node, left, right); }, _ => {}, } } extract_msrv_attr!(LateContext); } fn inverted_bin_op_eq_str(op: BinOpKind) -> Option<&'static str> { match op { BinOpKind::Eq => Some("!="), BinOpKind::Ne => Some("=="), _ => None, } } fn bin_op_eq_str(op: BinOpKind) -> Option<&'static str> { match op { BinOpKind::Eq => Some("=="), BinOpKind::Ne => Some("!="), _ => None, } } fn check_inverted_bool_in_condition( cx: &LateContext<'_>, expr_span: Span, op: BinOpKind, left: &Expr<'_>, right: &Expr<'_>, ) { if expr_span.from_expansion() || !cx.typeck_results().node_types()[left.hir_id].is_bool() || !cx.typeck_results().node_types()[right.hir_id].is_bool() { return; } let suggestion = match (left.kind, right.kind) { (ExprKind::Unary(UnOp::Not, left_sub), ExprKind::Unary(UnOp::Not, right_sub)) => { let Some(left) = left_sub.span.get_source_text(cx) else { return; }; let Some(right) = right_sub.span.get_source_text(cx) else { return; }; let Some(op) = bin_op_eq_str(op) else { return }; format!("{left} {op} {right}") }, (ExprKind::Unary(UnOp::Not, left_sub), _) => { let Some(left) = left_sub.span.get_source_text(cx) else { return; }; let Some(right) = right.span.get_source_text(cx) else { return; }; let Some(op) = inverted_bin_op_eq_str(op) else { return }; format!("{left} {op} {right}") }, (_, ExprKind::Unary(UnOp::Not, right_sub)) => { let Some(left) = left.span.get_source_text(cx) else { return; }; let Some(right) = right_sub.span.get_source_text(cx) else { return; }; let Some(op) = inverted_bin_op_eq_str(op) else { return }; format!("{left} {op} {right}") }, _ => return, }; span_lint_and_sugg( cx, NONMINIMAL_BOOL, expr_span, "this boolean expression can be simplified", "try", suggestion, Applicability::MachineApplicable, ); } fn check_simplify_not(cx: &LateContext<'_>, msrv: &Msrv, expr: &Expr<'_>) { if let ExprKind::Unary(UnOp::Not, inner) = &expr.kind && !expr.span.from_expansion() && !inner.span.from_expansion() && let Some(suggestion) = simplify_not(cx, msrv, inner) && cx.tcx.lint_level_at_node(NONMINIMAL_BOOL, expr.hir_id).0 != Level::Allow { span_lint_and_sugg( cx, NONMINIMAL_BOOL, expr.span, "this boolean expression can be simplified", "try", suggestion, Applicability::MachineApplicable, ); } } struct NonminimalBoolVisitor<'a, 'tcx> { cx: &'a LateContext<'tcx>, msrv: &'a Msrv, } use quine_mc_cluskey::Bool; struct Hir2Qmm<'a, 'tcx, 'v> { terminals: Vec<&'v Expr<'v>>, cx: &'a LateContext<'tcx>, } impl<'v> Hir2Qmm<'_, '_, 'v> { fn extract(&mut self, op: BinOpKind, a: &[&'v Expr<'_>], mut v: Vec) -> Result, String> { for a in a { if let ExprKind::Binary(binop, lhs, rhs) = &a.kind { if binop.node == op { v = self.extract(op, &[lhs, rhs], v)?; continue; } } v.push(self.run(a)?); } Ok(v) } fn run(&mut self, e: &'v Expr<'_>) -> Result { fn negate(bin_op_kind: BinOpKind) -> Option { match bin_op_kind { BinOpKind::Eq => Some(BinOpKind::Ne), BinOpKind::Ne => Some(BinOpKind::Eq), BinOpKind::Gt => Some(BinOpKind::Le), BinOpKind::Ge => Some(BinOpKind::Lt), BinOpKind::Lt => Some(BinOpKind::Ge), BinOpKind::Le => Some(BinOpKind::Gt), _ => None, } } // prevent folding of `cfg!` macros and the like if !e.span.from_expansion() { match &e.kind { ExprKind::Unary(UnOp::Not, inner) => return Ok(Bool::Not(Box::new(self.run(inner)?))), ExprKind::Binary(binop, lhs, rhs) => match &binop.node { BinOpKind::Or => { return Ok(Bool::Or(self.extract(BinOpKind::Or, &[lhs, rhs], Vec::new())?)); }, BinOpKind::And => { return Ok(Bool::And(self.extract(BinOpKind::And, &[lhs, rhs], Vec::new())?)); }, _ => (), }, ExprKind::Lit(lit) => match lit.node { LitKind::Bool(true) => return Ok(Bool::True), LitKind::Bool(false) => return Ok(Bool::False), _ => (), }, _ => (), } } if self.cx.typeck_results().expr_ty(e).is_never() { return Err("contains never type".to_owned()); } for (n, expr) in self.terminals.iter().enumerate() { if eq_expr_value(self.cx, e, expr) { #[expect(clippy::cast_possible_truncation)] return Ok(Bool::Term(n as u8)); } if let ExprKind::Binary(e_binop, e_lhs, e_rhs) = &e.kind && implements_ord(self.cx, e_lhs) && let ExprKind::Binary(expr_binop, expr_lhs, expr_rhs) = &expr.kind && negate(e_binop.node) == Some(expr_binop.node) && eq_expr_value(self.cx, e_lhs, expr_lhs) && eq_expr_value(self.cx, e_rhs, expr_rhs) { #[expect(clippy::cast_possible_truncation)] return Ok(Bool::Not(Box::new(Bool::Term(n as u8)))); } } let n = self.terminals.len(); self.terminals.push(e); if n < 32 { #[expect(clippy::cast_possible_truncation)] Ok(Bool::Term(n as u8)) } else { Err("too many literals".to_owned()) } } } struct SuggestContext<'a, 'tcx, 'v> { terminals: &'v [&'v Expr<'v>], cx: &'a LateContext<'tcx>, msrv: &'a Msrv, output: String, } impl SuggestContext<'_, '_, '_> { fn recurse(&mut self, suggestion: &Bool) -> Option<()> { use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True}; match suggestion { True => { self.output.push_str("true"); }, False => { self.output.push_str("false"); }, Not(inner) => match **inner { And(_) | Or(_) => { self.output.push('!'); self.output.push('('); self.recurse(inner); self.output.push(')'); }, Term(n) => { let terminal = self.terminals[n as usize]; if let Some(str) = simplify_not(self.cx, self.msrv, terminal) { self.output.push_str(&str); } else { self.output.push('!'); self.output.push_str(&terminal.span.get_source_text(self.cx)?); } }, True | False | Not(_) => { self.output.push('!'); self.recurse(inner)?; }, }, And(v) => { for (index, inner) in v.iter().enumerate() { if index > 0 { self.output.push_str(" && "); } if let Or(_) = *inner { self.output.push('('); self.recurse(inner); self.output.push(')'); } else { self.recurse(inner); } } }, Or(v) => { for (index, inner) in v.iter().rev().enumerate() { if index > 0 { self.output.push_str(" || "); } self.recurse(inner); } }, &Term(n) => { self.output.push_str( &self.terminals[n as usize] .span .source_callsite() .get_source_text(self.cx)?, ); }, } Some(()) } } fn simplify_not(cx: &LateContext<'_>, curr_msrv: &Msrv, expr: &Expr<'_>) -> Option { match &expr.kind { ExprKind::Binary(binop, lhs, rhs) => { if !implements_ord(cx, lhs) { return None; } match binop.node { BinOpKind::Eq => Some(" != "), BinOpKind::Ne => Some(" == "), BinOpKind::Lt => Some(" >= "), BinOpKind::Gt => Some(" <= "), BinOpKind::Le => Some(" > "), BinOpKind::Ge => Some(" < "), _ => None, } .and_then(|op| { let lhs_snippet = lhs.span.get_source_text(cx)?; let rhs_snippet = rhs.span.get_source_text(cx)?; if !(lhs_snippet.starts_with('(') && lhs_snippet.ends_with(')')) { if let (ExprKind::Cast(..), BinOpKind::Ge) = (&lhs.kind, binop.node) { // e.g. `(a as u64) < b`. Without the parens the `<` is // interpreted as a start of generic arguments for `u64` return Some(format!("({lhs_snippet}){op}{rhs_snippet}")); } } Some(format!("{lhs_snippet}{op}{rhs_snippet}")) }) }, ExprKind::MethodCall(path, receiver, args, _) => { let type_of_receiver = cx.typeck_results().expr_ty(receiver); if !is_type_diagnostic_item(cx, type_of_receiver, sym::Option) && !is_type_diagnostic_item(cx, type_of_receiver, sym::Result) { return None; } METHODS_WITH_NEGATION .iter() .copied() .flat_map(|(msrv, a, b)| vec![(msrv, a, b), (msrv, b, a)]) .find(|&(msrv, a, _)| msrv.is_none_or(|msrv| curr_msrv.meets(msrv)) && a == path.ident.name.as_str()) .and_then(|(_, _, neg_method)| { let negated_args = args .iter() .map(|arg| simplify_not(cx, curr_msrv, arg)) .collect::>>()? .join(", "); Some(format!( "{}.{neg_method}({negated_args})", receiver.span.get_source_text(cx)? )) }) }, ExprKind::Closure(closure) => { let body = cx.tcx.hir().body(closure.body); let params = body .params .iter() .map(|param| param.span.get_source_text(cx).map(|t| t.to_string())) .collect::>>()? .join(", "); let negated = simplify_not(cx, curr_msrv, body.value)?; Some(format!("|{params}| {negated}")) }, ExprKind::Unary(UnOp::Not, expr) => expr.span.get_source_text(cx).map(|t| t.to_string()), _ => None, } } fn suggest(cx: &LateContext<'_>, msrv: &Msrv, suggestion: &Bool, terminals: &[&Expr<'_>]) -> String { let mut suggest_context = SuggestContext { terminals, cx, msrv, output: String::new(), }; suggest_context.recurse(suggestion); suggest_context.output } fn simple_negate(b: Bool) -> Bool { use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True}; match b { True => False, False => True, t @ Term(_) => Not(Box::new(t)), And(mut v) => { for el in &mut v { *el = simple_negate(std::mem::replace(el, True)); } Or(v) }, Or(mut v) => { for el in &mut v { *el = simple_negate(std::mem::replace(el, True)); } And(v) }, Not(inner) => *inner, } } #[derive(Default)] struct Stats { terminals: [usize; 32], negations: usize, ops: usize, } fn terminal_stats(b: &Bool) -> Stats { fn recurse(b: &Bool, stats: &mut Stats) { match b { True | False => stats.ops += 1, Not(inner) => { match **inner { And(_) | Or(_) => stats.ops += 1, // brackets are also operations _ => stats.negations += 1, } recurse(inner, stats); }, And(v) | Or(v) => { stats.ops += v.len() - 1; for inner in v { recurse(inner, stats); } }, &Term(n) => stats.terminals[n as usize] += 1, } } use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True}; let mut stats = Stats::default(); recurse(b, &mut stats); stats } impl<'tcx> NonminimalBoolVisitor<'_, 'tcx> { fn bool_expr(&self, e: &'tcx Expr<'_>) { let mut h2q = Hir2Qmm { terminals: Vec::new(), cx: self.cx, }; if let Ok(expr) = h2q.run(e) { let stats = terminal_stats(&expr); if stats.ops > 7 { // QMC has exponentially slow behavior as the number of ops increases. // See #825, #13206 return; } let mut simplified = expr.simplify(); for simple in Bool::Not(Box::new(expr)).simplify() { match simple { Bool::Not(_) | Bool::True | Bool::False => {}, _ => simplified.push(Bool::Not(Box::new(simple.clone()))), } let simple_negated = simple_negate(simple); if simplified.iter().any(|s| *s == simple_negated) { continue; } simplified.push(simple_negated); } let mut improvements = Vec::with_capacity(simplified.len()); 'simplified: for suggestion in &simplified { let simplified_stats = terminal_stats(suggestion); let mut improvement = false; for i in 0..32 { // ignore any "simplifications" that end up requiring a terminal more often // than in the original expression if stats.terminals[i] < simplified_stats.terminals[i] { continue 'simplified; } if stats.terminals[i] != 0 && simplified_stats.terminals[i] == 0 { span_lint_hir_and_then( self.cx, OVERLY_COMPLEX_BOOL_EXPR, e.hir_id, e.span, "this boolean expression contains a logic bug", |diag| { diag.span_help( h2q.terminals[i].span, "this expression can be optimized out by applying boolean operations to the \ outer expression", ); diag.span_suggestion( e.span, "it would look like the following", suggest(self.cx, self.msrv, suggestion, &h2q.terminals), // nonminimal_bool can produce minimal but // not human readable expressions (#3141) Applicability::Unspecified, ); }, ); // don't also lint `NONMINIMAL_BOOL` return; } // if the number of occurrences of a terminal decreases or any of the stats // decreases while none increases improvement |= (stats.terminals[i] > simplified_stats.terminals[i]) || (stats.negations > simplified_stats.negations && stats.ops == simplified_stats.ops) || (stats.ops > simplified_stats.ops && stats.negations == simplified_stats.negations); } if improvement { improvements.push(suggestion); } } let nonminimal_bool_lint = |mut suggestions: Vec<_>| { if self.cx.tcx.lint_level_at_node(NONMINIMAL_BOOL, e.hir_id).0 != Level::Allow { suggestions.sort(); span_lint_hir_and_then( self.cx, NONMINIMAL_BOOL, e.hir_id, e.span, "this boolean expression can be simplified", |diag| { diag.span_suggestions( e.span, "try", suggestions, // nonminimal_bool can produce minimal but // not human readable expressions (#3141) Applicability::Unspecified, ); }, ); } }; if improvements.is_empty() { check_simplify_not(self.cx, self.msrv, e); } else { nonminimal_bool_lint( improvements .into_iter() .map(|suggestion| suggest(self.cx, self.msrv, suggestion, &h2q.terminals)) .collect(), ); } } } } impl<'tcx> Visitor<'tcx> for NonminimalBoolVisitor<'_, 'tcx> { fn visit_expr(&mut self, e: &'tcx Expr<'_>) { if !e.span.from_expansion() { match &e.kind { ExprKind::Binary(binop, _, _) if binop.node == BinOpKind::Or || binop.node == BinOpKind::And => { self.bool_expr(e); }, ExprKind::Unary(UnOp::Not, inner) => { if let ExprKind::Unary(UnOp::Not, ex) = inner.kind && !self.cx.typeck_results().node_types()[ex.hir_id].is_bool() { return; } if self.cx.typeck_results().node_types()[inner.hir_id].is_bool() { self.bool_expr(e); } }, _ => {}, } } walk_expr(self, e); } } fn implements_ord(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { let ty = cx.typeck_results().expr_ty(expr); cx.tcx .get_diagnostic_item(sym::Ord) .map_or(false, |id| implements_trait(cx, ty, id, &[])) }