//! This lint is **warn** by default
use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
+use clippy_utils::higher;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::sugg::Sugg;
-use clippy_utils::{is_else_clause, is_expn_of};
+use clippy_utils::{get_parent_node, is_else_clause, is_expn_of, peel_blocks, peel_blocks_with_stmt};
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, HirId, Node, 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 {
+ /// ### What it does
+ /// Checks for expressions of the form `if c { true } else {
/// false }` (or vice versa) and suggests using the condition directly.
///
- /// **Why is this bad?** Redundant code.
+ /// ### Why is this bad?
+ /// Redundant code.
///
- /// **Known problems:** Maybe false positives: Sometimes, the two branches are
+ /// ### Known problems
+ /// Maybe false positives: Sometimes, the two branches are
/// painstakingly documented (which we, of course, do not detect), so they *may*
/// have some value. Even then, the documentation can be rewritten to match the
/// shorter code.
///
- /// **Example:**
- /// ```rust,ignore
+ /// ### Example
+ /// ```rust
+ /// # let x = true;
/// if x {
/// false
/// } else {
/// true
/// }
+ /// # ;
/// ```
- /// Could be written as
- /// ```rust,ignore
+ ///
+ /// Use instead:
+ /// ```rust
+ /// # let x = true;
/// !x
+ /// # ;
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub NEEDLESS_BOOL,
complexity,
"if-statements with plain booleans in the then- and else-clause, e.g., `if p { true } else { false }`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for expressions of the form `x == true`,
+ /// ### What it does
+ /// Checks for expressions of the form `x == true`,
/// `x != true` and order comparisons such as `x < true` (or vice versa) and
/// suggest using the variable directly.
///
- /// **Why is this bad?** Unnecessary code.
+ /// ### Why is this bad?
+ /// Unnecessary code.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// if x == true {}
/// if y == false {}
/// if x {}
/// if !y {}
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub BOOL_COMPARISON,
complexity,
"comparing a variable to a boolean, e.g., `if x == true` or `if x != true`"
declare_lint_pass!(NeedlessBool => [NEEDLESS_BOOL]);
+fn condition_needs_parentheses(e: &Expr<'_>) -> bool {
+ let mut inner = e;
+ while let ExprKind::Binary(_, i, _)
+ | ExprKind::Call(i, _)
+ | ExprKind::Cast(i, _)
+ | ExprKind::Type(i, _)
+ | ExprKind::Index(i, _) = inner.kind
+ {
+ if matches!(
+ i.kind,
+ ExprKind::Block(..)
+ | ExprKind::ConstBlock(..)
+ | ExprKind::If(..)
+ | ExprKind::Loop(..)
+ | ExprKind::Match(..)
+ ) {
+ return true;
+ }
+ inner = i;
+ }
+ false
+}
+
+fn is_parent_stmt(cx: &LateContext<'_>, id: HirId) -> bool {
+ matches!(
+ get_parent_node(cx.tcx, id),
+ Some(Node::Stmt(..) | Node::Block(Block { stmts: &[], .. }))
+ )
+}
+
impl<'tcx> LateLintPass<'tcx> for NeedlessBool {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
use self::Expression::{Bool, RetBool};
- if let ExprKind::If(pred, then_block, Some(else_expr)) = e.kind {
+ if e.span.from_expansion() {
+ return;
+ }
+ if let Some(higher::If {
+ cond,
+ then,
+ r#else: Some(r#else),
+ }) = higher::If::hir(e)
+ {
let reduce = |ret, not| {
let mut applicability = Applicability::MachineApplicable;
- let snip = Sugg::hir_with_applicability(cx,
pred, "<predicate>", &mut applicability);
+ let snip = Sugg::hir_with_applicability(cx,
cond, "<predicate>", &mut applicability);
let mut snip = if not { !snip } else { snip };
if ret {
snip = snip.blockify();
}
+ if condition_needs_parentheses(cond) && is_parent_stmt(cx, e.hir_id) {
+ snip = snip.maybe_par();
+ }
+
span_lint_and_sugg(
cx,
NEEDLESS_BOOL,
applicability,
);
};
- if let ExprKind::Block(then_block, _) = then_block.kind {
- match (fetch_bool_block(then_block), fetch_bool_expr(else_expr)) {
+ if let Some((a, b)) = fetch_bool_block(then).and_then(|a| Some((a, fetch_bool_block(r#else)?))) {
+ match (a, b) {
(RetBool(true), RetBool(true)) | (Bool(true), Bool(true)) => {
span_lint(
cx,
(Bool(false), Bool(true)) => reduce(false, true),
_ => (),
}
- } else {
- panic!("IfExpr `then` node is not an `ExprKind::Block`");
}
}
}
BinOpKind::Eq => {
let true_case = Some((|h| h, "equality checks against true are unnecessary"));
let false_case = Some((
- |h: Sugg<'_>| !h,
+ |h: Sugg<'tcx>| !h,
"equality checks against false can be replaced by a negation",
));
check_comparison(cx, e, true_case, false_case, true_case, false_case, ignore_no_literal);
},
BinOpKind::Ne => {
let true_case = Some((
- |h: Sugg<'_>| !h,
+ |h: Sugg<'tcx>| !h,
"inequality checks against true can be replaced by a negation",
));
let false_case = Some((|h| h, "inequality checks against false are unnecessary"));
ignore_case,
Some((|h| h, "greater than checks against false are unnecessary")),
Some((
- |h: Sugg<'_>| !h,
+ |h: Sugg<'tcx>| !h,
"less than comparison against true can be replaced by a negation",
)),
ignore_case,
Some((
- |l: Sugg<'_>, r: Sugg<'_>| (!l).bit_and(&r),
+ |l: Sugg<'tcx>, r: Sugg<'tcx>| (!l).bit_and(&r),
"order comparisons between booleans can be simplified",
)),
),
cx,
e,
Some((
- |h: Sugg<'_>| !h,
+ |h: Sugg<'tcx>| !h,
"less than comparison against true can be replaced by a negation",
)),
ignore_case,
ignore_case,
Some((|h| h, "greater than checks against false are unnecessary")),
Some((
- |l: Sugg<'_>, r: Sugg<'_>| l.bit_and(&(!r)),
+ |l: Sugg<'tcx>, r: Sugg<'tcx>| l.bit_and(&(!r)),
"order comparisons between booleans can be simplified",
)),
),
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::{Bool, Other};
-
if let ExprKind::Binary(op, left_side, right_side) = e.kind {
let (l_ty, r_ty) = (
cx.typeck_results().expr_ty(left_side),
if l_ty.is_bool() && r_ty.is_bool() {
let mut applicability = Applicability::MachineApplicable;
- if let BinOpKind::Eq = op.node {
+ if op.node == BinOpKind::Eq {
let expression_info = one_side_is_unary_not(left_side, right_side);
if expression_info.one_side_is_unary_not {
span_lint_and_sugg(
}
match (fetch_bool_expr(left_side), fetch_bool_expr(right_side)) {
- (Bool(true), Other) => left_true.map_or((), |(h, m)| {
+ (Some(true), None) => left_true.map_or((), |(h, m)| {
suggest_bool_comparison(cx, e, right_side, applicability, m, h);
}),
- (Other, Bool(true)) => right_true.map_or((), |(h, m)| {
+ (None, Some(true)) => right_true.map_or((), |(h, m)| {
suggest_bool_comparison(cx, e, left_side, applicability, m, h);
}),
- (Bool(false), Other) => left_false.map_or((), |(h, m)| {
+ (Some(false), None) => left_false.map_or((), |(h, m)| {
suggest_bool_comparison(cx, e, right_side, applicability, m, h);
}),
- (Other, Bool(false)) => right_false.map_or((), |(h, m)| {
+ (None, Some(false)) => right_false.map_or((), |(h, m)| {
suggest_bool_comparison(cx, e, left_side, applicability, m, h);
}),
- (Other, Other) => no_literal.map_or((), |(h, m)| {
+ (None, None) => no_literal.map_or((), |(h, m)| {
let left_side = Sugg::hir_with_applicability(cx, left_side, "..", &mut applicability);
let right_side = Sugg::hir_with_applicability(cx, right_side, "..", &mut applicability);
span_lint_and_sugg(
enum Expression {
Bool(bool),
RetBool(bool),
- Other,
}
-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(e) = e.kind {
- if let ExprKind::Ret(_) = e.kind {
- fetch_bool_expr(e)
- } else {
- Expression::Other
- }
- } else {
- Expression::Other
- }
- },
- _ => Expression::Other,
+fn fetch_bool_block(expr: &Expr<'_>) -> Option<Expression> {
+ match peel_blocks_with_stmt(expr).kind {
+ ExprKind::Ret(Some(ret)) => Some(Expression::RetBool(fetch_bool_expr(ret)?)),
+ _ => Some(Expression::Bool(fetch_bool_expr(expr)?)),
}
}
-fn fetch_bool_expr(expr: &Expr<'_>) -> Expression {
- match expr.kind {
- ExprKind::Block(block, _) => fetch_bool_block(block),
- ExprKind::Lit(ref lit_ptr) => {
- if let LitKind::Bool(value) = lit_ptr.node {
- Expression::Bool(value)
- } else {
- Expression::Other
- }
- },
- ExprKind::Ret(Some(expr)) => match fetch_bool_expr(expr) {
- Expression::Bool(value) => Expression::RetBool(value),
- _ => Expression::Other,
- },
- _ => Expression::Other,
+fn fetch_bool_expr(expr: &Expr<'_>) -> Option<bool> {
+ if let ExprKind::Lit(ref lit_ptr) = peel_blocks(expr).kind {
+ if let LitKind::Bool(value) = lit_ptr.node {
+ return Some(value);
+ }
}
+ None
}
projects / rust.git / blobdiff