| use crate::utils::{ |
| get_trait_def_id, implements_trait, in_macro, match_type, paths, snippet_opt, span_lint_and_sugg, |
| span_lint_and_then, SpanlessEq, |
| }; |
| use if_chain::if_chain; |
| use rustc::hir::map::Map; |
| use rustc_ast::ast::LitKind; |
| use rustc_errors::Applicability; |
| use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor}; |
| use rustc_hir::{BinOpKind, Body, Expr, ExprKind, FnDecl, HirId, UnOp}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::source_map::Span; |
| |
| 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 // should be: if a |
| /// if !(a == b) // should be: if a != b |
| /// ``` |
| 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:** |
| /// ```ignore |
| /// if a && b || a { ... } |
| /// ``` |
| /// The `b` is unnecessary, the expression is equivalent to `if a`. |
| pub LOGIC_BUG, |
| correctness, |
| "boolean expressions that contain terminals which can be eliminated" |
| } |
| |
| // For each pairs, both orders are considered. |
| const METHODS_WITH_NEGATION: [(&str, &str); 2] = [("is_some", "is_none"), ("is_err", "is_ok")]; |
| |
| declare_lint_pass!(NonminimalBool => [NONMINIMAL_BOOL, LOGIC_BUG]); |
| |
| impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonminimalBool { |
| fn check_fn( |
| &mut self, |
| cx: &LateContext<'a, 'tcx>, |
| _: FnKind<'tcx>, |
| _: &'tcx FnDecl<'_>, |
| body: &'tcx Body<'_>, |
| _: Span, |
| _: HirId, |
| ) { |
| NonminimalBoolVisitor { cx }.visit_body(body) |
| } |
| } |
| |
| struct NonminimalBoolVisitor<'a, 'tcx> { |
| cx: &'a LateContext<'a, 'tcx>, |
| } |
| |
| use quine_mc_cluskey::Bool; |
| struct Hir2Qmm<'a, 'tcx, 'v> { |
| terminals: Vec<&'v Expr<'v>>, |
| cx: &'a LateContext<'a, 'tcx>, |
| } |
| |
| impl<'a, 'tcx, 'v> Hir2Qmm<'a, 'tcx, 'v> { |
| fn extract(&mut self, op: BinOpKind, a: &[&'v Expr<'_>], mut v: Vec<Bool>) -> Result<Vec<Bool>, 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<Bool, String> { |
| fn negate(bin_op_kind: BinOpKind) -> Option<BinOpKind> { |
| 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::UnNot, inner) => return Ok(Bool::Not(box 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), |
| _ => (), |
| }, |
| _ => (), |
| } |
| } |
| for (n, expr) in self.terminals.iter().enumerate() { |
| if SpanlessEq::new(self.cx).ignore_fn().eq_expr(e, expr) { |
| #[allow(clippy::cast_possible_truncation)] |
| return Ok(Bool::Term(n as u8)); |
| } |
| |
| if_chain! { |
| if let ExprKind::Binary(e_binop, e_lhs, e_rhs) = &e.kind; |
| if implements_ord(self.cx, e_lhs); |
| if let ExprKind::Binary(expr_binop, expr_lhs, expr_rhs) = &expr.kind; |
| if negate(e_binop.node) == Some(expr_binop.node); |
| if SpanlessEq::new(self.cx).ignore_fn().eq_expr(e_lhs, expr_lhs); |
| if SpanlessEq::new(self.cx).ignore_fn().eq_expr(e_rhs, expr_rhs); |
| then { |
| #[allow(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 { |
| #[allow(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<'a, 'tcx>, |
| output: String, |
| } |
| |
| impl<'a, 'tcx, 'v> SuggestContext<'a, 'tcx, 'v> { |
| 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, terminal) { |
| self.output.push_str(&str) |
| } else { |
| self.output.push('!'); |
| let snip = snippet_opt(self.cx, terminal.span)?; |
| self.output.push_str(&snip); |
| } |
| }, |
| 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) => { |
| let snip = snippet_opt(self.cx, self.terminals[n as usize].span)?; |
| self.output.push_str(&snip); |
| }, |
| } |
| Some(()) |
| } |
| } |
| |
| fn simplify_not(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> Option<String> { |
| 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| { |
| Some(format!( |
| "{}{}{}", |
| snippet_opt(cx, lhs.span)?, |
| op, |
| snippet_opt(cx, rhs.span)? |
| )) |
| }) |
| }, |
| ExprKind::MethodCall(path, _, args) if args.len() == 1 => { |
| let type_of_receiver = cx.tables.expr_ty(&args[0]); |
| if !match_type(cx, type_of_receiver, &paths::OPTION) && !match_type(cx, type_of_receiver, &paths::RESULT) { |
| return None; |
| } |
| METHODS_WITH_NEGATION |
| .iter() |
| .cloned() |
| .flat_map(|(a, b)| vec![(a, b), (b, a)]) |
| .find(|&(a, _)| { |
| let path: &str = &path.ident.name.as_str(); |
| a == path |
| }) |
| .and_then(|(_, neg_method)| Some(format!("{}.{}()", snippet_opt(cx, args[0].span)?, neg_method))) |
| }, |
| _ => None, |
| } |
| } |
| |
| fn suggest(cx: &LateContext<'_, '_>, suggestion: &Bool, terminals: &[&Expr<'_>]) -> String { |
| let mut suggest_context = SuggestContext { |
| terminals, |
| cx, |
| 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<'a, 'tcx> NonminimalBoolVisitor<'a, '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) { |
| if h2q.terminals.len() > 8 { |
| // QMC has exponentially slow behavior as the number of terminals increases |
| // 8 is reasonable, it takes approximately 0.2 seconds. |
| // See #825 |
| return; |
| } |
| |
| let stats = terminal_stats(&expr); |
| 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_and_then( |
| self.cx, |
| LOGIC_BUG, |
| e.span, |
| "this boolean expression contains a logic bug", |
| |db| { |
| db.span_help( |
| h2q.terminals[i].span, |
| "this expression can be optimized out by applying boolean operations to the \ |
| outer expression", |
| ); |
| db.span_suggestion( |
| e.span, |
| "it would look like the following", |
| suggest(self.cx, 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 = |suggestions: Vec<_>| { |
| span_lint_and_then( |
| self.cx, |
| NONMINIMAL_BOOL, |
| e.span, |
| "this boolean expression can be simplified", |
| |db| { |
| db.span_suggestions( |
| e.span, |
| "try", |
| suggestions.into_iter(), |
| // nonminimal_bool can produce minimal but |
| // not human readable expressions (#3141) |
| Applicability::Unspecified, |
| ); |
| }, |
| ); |
| }; |
| if improvements.is_empty() { |
| let mut visitor = NotSimplificationVisitor { cx: self.cx }; |
| visitor.visit_expr(e); |
| } else { |
| nonminimal_bool_lint( |
| improvements |
| .into_iter() |
| .map(|suggestion| suggest(self.cx, suggestion, &h2q.terminals)) |
| .collect(), |
| ); |
| } |
| } |
| } |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for NonminimalBoolVisitor<'a, 'tcx> { |
| type Map = Map<'tcx>; |
| |
| fn visit_expr(&mut self, e: &'tcx Expr<'_>) { |
| if in_macro(e.span) { |
| return; |
| } |
| match &e.kind { |
| ExprKind::Binary(binop, _, _) if binop.node == BinOpKind::Or || binop.node == BinOpKind::And => { |
| self.bool_expr(e) |
| }, |
| ExprKind::Unary(UnOp::UnNot, inner) => { |
| if self.cx.tables.node_types()[inner.hir_id].is_bool() { |
| self.bool_expr(e); |
| } else { |
| walk_expr(self, e); |
| } |
| }, |
| _ => walk_expr(self, e), |
| } |
| } |
| fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> { |
| NestedVisitorMap::None |
| } |
| } |
| |
| fn implements_ord<'a, 'tcx>(cx: &'a LateContext<'a, 'tcx>, expr: &Expr<'_>) -> bool { |
| let ty = cx.tables.expr_ty(expr); |
| get_trait_def_id(cx, &paths::ORD).map_or(false, |id| implements_trait(cx, ty, id, &[])) |
| } |
| |
| struct NotSimplificationVisitor<'a, 'tcx> { |
| cx: &'a LateContext<'a, 'tcx>, |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for NotSimplificationVisitor<'a, 'tcx> { |
| type Map = Map<'tcx>; |
| |
| fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { |
| if let ExprKind::Unary(UnOp::UnNot, inner) = &expr.kind { |
| if let Some(suggestion) = simplify_not(self.cx, inner) { |
| span_lint_and_sugg( |
| self.cx, |
| NONMINIMAL_BOOL, |
| expr.span, |
| "this boolean expression can be simplified", |
| "try", |
| suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| walk_expr(self, expr); |
| } |
| fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> { |
| NestedVisitorMap::None |
| } |
| } |