//! This lint is **warn** by default
use crate::utils::sugg::Sugg;
-use crate::utils::{higher, in_macro_or_desugar, span_lint, span_lint_and_sugg};
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_lint_pass, declare_tool_lint};
+use crate::utils::{
+ higher, is_expn_of, parent_node_is_if_expr, snippet_with_applicability, span_lint, span_lint_and_sugg,
+};
+use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use syntax::ast::LitKind;
-use syntax::source_map::Spanned;
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Spanned;
+use rustc_span::Span;
declare_clippy_lint! {
/// **What it does:** Checks for expressions of the form `if c { true } else {
- /// false }`
- /// (or vice versa) and suggest using the condition directly.
+ /// false }` (or vice versa) and suggests using the condition directly.
///
/// **Why is this bad?** Redundant code.
///
/// shorter code.
///
/// **Example:**
- /// ```rust
+ /// ```rust,ignore
/// if x {
/// false
/// } else {
/// true
/// }
/// ```
+ /// Could be written as
+ /// ```rust,ignore
+ /// !x
+ /// ```
pub NEEDLESS_BOOL,
complexity,
"if-statements with plain booleans in the then- and else-clause, e.g., `if p { true } else { false }`"
/// **Known problems:** None.
///
/// **Example:**
- /// ```rust
- /// if x == true {} // could be `if x { }`
+ /// ```rust,ignore
+ /// if x == true {}
+ /// if y == false {}
+ /// ```
+ /// use `x` directly:
+ /// ```rust,ignore
+ /// if x {}
+ /// if !y {}
/// ```
pub BOOL_COMPARISON,
complexity,
declare_lint_pass!(NeedlessBool => [NEEDLESS_BOOL]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBool {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
- use self::Expression::*;
+impl<'tcx> LateLintPass<'tcx> for NeedlessBool {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
+ use self::Expression::{Bool, RetBool};
if let Some((ref pred, ref then_block, Some(ref else_expr))) = higher::if_block(&e) {
let reduce = |ret, not| {
let mut applicability = Applicability::MachineApplicable;
applicability,
);
};
- if let ExprKind::Block(ref then_block, _) = then_block.node {
+ if let ExprKind::Block(ref then_block, _) = then_block.kind {
match (fetch_bool_block(then_block), fetch_bool_expr(else_expr)) {
(RetBool(true), RetBool(true)) | (Bool(true), Bool(true)) => {
span_lint(
_ => (),
}
} else {
- panic!("IfExpr 'then' node is not an ExprKind::Block");
+ panic!("IfExpr `then` node is not an `ExprKind::Block`");
}
}
}
}
-fn parent_node_is_if_expr<'a, 'b>(expr: &Expr, cx: &LateContext<'a, 'b>) -> bool {
- let parent_id = cx.tcx.hir().get_parent_node(expr.hir_id);
- let parent_node = cx.tcx.hir().get(parent_id);
-
- if let rustc::hir::Node::Expr(e) = parent_node {
- if higher::if_block(&e).is_some() {
- return true;
- }
- }
-
- false
-}
-
declare_lint_pass!(BoolComparison => [BOOL_COMPARISON]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoolComparison {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
- if in_macro_or_desugar(e.span) {
+impl<'tcx> LateLintPass<'tcx> for BoolComparison {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
+ if e.span.from_expansion() {
return;
}
- if let ExprKind::Binary(Spanned { node, .. }, ..) = e.node {
+ if let ExprKind::Binary(Spanned { node, .. }, ..) = e.kind {
let ignore_case = None::<(fn(_) -> _, &str)>;
let ignore_no_literal = None::<(fn(_, _) -> _, &str)>;
match node {
}
}
+struct ExpressionInfoWithSpan {
+ one_side_is_unary_not: bool,
+ left_span: Span,
+ right_span: Span,
+}
+
+fn is_unary_not(e: &Expr<'_>) -> (bool, Span) {
+ if let ExprKind::Unary(UnOp::UnNot, operand) = e.kind {
+ return (true, operand.span);
+ }
+ (false, e.span)
+}
+
+fn one_side_is_unary_not<'tcx>(left_side: &'tcx Expr<'_>, right_side: &'tcx Expr<'_>) -> ExpressionInfoWithSpan {
+ let left = is_unary_not(left_side);
+ let right = is_unary_not(right_side);
+
+ ExpressionInfoWithSpan {
+ one_side_is_unary_not: left.0 != right.0,
+ left_span: left.1,
+ right_span: right.1,
+ }
+}
+
fn check_comparison<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- e: &'tcx Expr,
+ cx: &LateContext<'tcx>,
+ e: &'tcx Expr<'_>,
left_true: Option<(impl FnOnce(Sugg<'a>) -> Sugg<'a>, &str)>,
left_false: Option<(impl FnOnce(Sugg<'a>) -> Sugg<'a>, &str)>,
right_true: Option<(impl FnOnce(Sugg<'a>) -> Sugg<'a>, &str)>,
right_false: Option<(impl FnOnce(Sugg<'a>) -> Sugg<'a>, &str)>,
no_literal: Option<(impl FnOnce(Sugg<'a>, Sugg<'a>) -> Sugg<'a>, &str)>,
) {
- use self::Expression::*;
+ use self::Expression::{Bool, Other};
- if let ExprKind::Binary(_, ref left_side, ref right_side) = e.node {
- let (l_ty, r_ty) = (cx.tables.expr_ty(left_side), cx.tables.expr_ty(right_side));
+ if let ExprKind::Binary(op, ref left_side, ref right_side) = e.kind {
+ let (l_ty, r_ty) = (
+ cx.typeck_results().expr_ty(left_side),
+ cx.typeck_results().expr_ty(right_side),
+ );
+ if is_expn_of(left_side.span, "cfg").is_some() || is_expn_of(right_side.span, "cfg").is_some() {
+ return;
+ }
if l_ty.is_bool() && r_ty.is_bool() {
let mut applicability = Applicability::MachineApplicable;
+
+ if let BinOpKind::Eq = op.node {
+ let expression_info = one_side_is_unary_not(&left_side, &right_side);
+ if expression_info.one_side_is_unary_not {
+ span_lint_and_sugg(
+ cx,
+ BOOL_COMPARISON,
+ e.span,
+ "this comparison might be written more concisely",
+ "try simplifying it as shown",
+ format!(
+ "{} != {}",
+ snippet_with_applicability(cx, expression_info.left_span, "..", &mut applicability),
+ snippet_with_applicability(cx, expression_info.right_span, "..", &mut applicability)
+ ),
+ applicability,
+ )
+ }
+ }
+
match (fetch_bool_expr(left_side), fetch_bool_expr(right_side)) {
(Bool(true), Other) => left_true.map_or((), |(h, m)| {
suggest_bool_comparison(cx, e, right_side, applicability, m, h)
}
fn suggest_bool_comparison<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- e: &'tcx Expr,
- expr: &Expr,
+ cx: &LateContext<'tcx>,
+ e: &'tcx Expr<'_>,
+ expr: &Expr<'_>,
mut applicability: Applicability,
message: &str,
conv_hint: impl FnOnce(Sugg<'a>) -> Sugg<'a>,
) {
- let hint = Sugg::hir_with_applicability(cx, expr, "..", &mut applicability);
+ let hint = if expr.span.from_expansion() {
+ if applicability != Applicability::Unspecified {
+ applicability = Applicability::MaybeIncorrect;
+ }
+ Sugg::hir_with_macro_callsite(cx, expr, "..")
+ } else {
+ Sugg::hir_with_applicability(cx, expr, "..", &mut applicability)
+ };
span_lint_and_sugg(
cx,
BOOL_COMPARISON,
Other,
}
-fn fetch_bool_block(block: &Block) -> Expression {
+fn fetch_bool_block(block: &Block<'_>) -> Expression {
match (&*block.stmts, block.expr.as_ref()) {
(&[], Some(e)) => fetch_bool_expr(&**e),
(&[ref e], None) => {
- if let StmtKind::Semi(ref e) = e.node {
- if let ExprKind::Ret(_) = e.node {
+ if let StmtKind::Semi(ref e) = e.kind {
+ if let ExprKind::Ret(_) = e.kind {
fetch_bool_expr(&**e)
} else {
Expression::Other
}
}
-fn fetch_bool_expr(expr: &Expr) -> Expression {
- match expr.node {
+fn fetch_bool_expr(expr: &Expr<'_>) -> Expression {
+ match expr.kind {
ExprKind::Block(ref block, _) => fetch_bool_block(block),
ExprKind::Lit(ref lit_ptr) => {
if let LitKind::Bool(value) = lit_ptr.node {
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