-// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
//! Checks for needless boolean results of if-else expressions
//!
//! This lint is **warn** by default
-use crate::rustc::hir::*;
-use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use crate::rustc::{declare_tool_lint, lint_array};
-use crate::rustc_errors::Applicability;
-use crate::syntax::ast::LitKind;
-use crate::syntax::source_map::Spanned;
use crate::utils::sugg::Sugg;
-use crate::utils::{in_macro, span_lint, span_lint_and_sugg};
-
-/// **What it does:** Checks for expressions of the form `if c { true } else {
-/// false }`
-/// (or vice versa) and suggest using the condition directly.
-///
-/// **Why is this bad?** Redundant code.
-///
-/// **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
-/// if x {
-/// false
-/// } else {
-/// true
-/// }
-/// ```
+use crate::utils::{higher, 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 rustc_errors::Applicability;
+use syntax::ast::LitKind;
+use syntax::source_map::Spanned;
+
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.
+ ///
+ /// **Why is this bad?** Redundant code.
+ ///
+ /// **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
+ /// 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 }`"
+ "if-statements with plain booleans in the then- and else-clause, e.g., `if p { true } else { false }`"
}
-/// **What it does:** Checks for expressions of the form `x == true` and
-/// `x != true` (or vice versa) and suggest using the variable directly.
-///
-/// **Why is this bad?** Unnecessary code.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// if x == true {} // could be `if x { }`
-/// ```
declare_clippy_lint! {
+ /// **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.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// if x == true {} // could be `if x { }`
+ /// ```
pub BOOL_COMPARISON,
complexity,
- "comparing a variable to a boolean, e.g. `if x == true` or `if x != true`"
+ "comparing a variable to a boolean, e.g., `if x == true` or `if x != true`"
}
-#[derive(Copy, Clone)]
-pub struct NeedlessBool;
-
-impl LintPass for NeedlessBool {
- fn get_lints(&self) -> LintArray {
- lint_array!(NEEDLESS_BOOL)
- }
-}
+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::*;
- if let ExprKind::If(ref pred, ref then_block, Some(ref else_expr)) = e.node {
+ 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;
let snip = Sugg::hir_with_applicability(cx, pred, "<predicate>", &mut applicability);
- let snip = if not { !snip } else { snip };
+ let mut snip = if not { !snip } else { snip };
- let hint = if ret {
- format!("return {}", snip)
- } else {
- snip.to_string()
- };
+ if ret {
+ snip = snip.make_return();
+ }
+
+ if parent_node_is_if_expr(&e, &cx) {
+ snip = snip.blockify()
+ }
span_lint_and_sugg(
cx,
e.span,
"this if-then-else expression returns a bool literal",
"you can reduce it to",
- hint,
+ snip.to_string(),
applicability,
);
};
}
}
-#[derive(Copy, Clone)]
-pub struct BoolComparison;
+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);
-impl LintPass for BoolComparison {
- fn get_lints(&self) -> LintArray {
- lint_array!(BOOL_COMPARISON)
+ match parent_node {
+ rustc::hir::Node::Expr(e) => higher::if_block(&e).is_some(),
+ rustc::hir::Node::Arm(e) => higher::if_block(&e.body).is_some(),
+ _ => 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(e.span) {
+ if e.span.from_expansion() {
return;
}
if let ExprKind::Binary(Spanned { node, .. }, ..) = e.node {
+ let ignore_case = None::<(fn(_) -> _, &str)>;
+ let ignore_no_literal = None::<(fn(_, _) -> _, &str)>;
match node {
- BinOpKind::Eq => check_comparison(
+ BinOpKind::Eq => {
+ let true_case = Some((|h| h, "equality checks against true are unnecessary"));
+ let false_case = Some((
+ |h: Sugg<'_>| !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,
+ "inequality checks against true can be replaced by a negation",
+ ));
+ let false_case = Some((|h| h, "inequality checks against false are unnecessary"));
+ check_comparison(cx, e, true_case, false_case, true_case, false_case, ignore_no_literal)
+ },
+ BinOpKind::Lt => check_comparison(
cx,
e,
- "equality checks against true are unnecessary",
- "equality checks against false can be replaced by a negation",
- |h| h,
- |h| !h,
+ ignore_case,
+ Some((|h| h, "greater than checks against false are unnecessary")),
+ Some((
+ |h: Sugg<'_>| !h,
+ "less than comparison against true can be replaced by a negation",
+ )),
+ ignore_case,
+ Some((
+ |l: Sugg<'_>, r: Sugg<'_>| (!l).bit_and(&r),
+ "order comparisons between booleans can be simplified",
+ )),
),
- BinOpKind::Ne => check_comparison(
+ BinOpKind::Gt => check_comparison(
cx,
e,
- "inequality checks against true can be replaced by a negation",
- "inequality checks against false are unnecessary",
- |h| !h,
- |h| h,
+ Some((
+ |h: Sugg<'_>| !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)),
+ "order comparisons between booleans can be simplified",
+ )),
),
_ => (),
}
fn check_comparison<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
e: &'tcx Expr,
- true_message: &str,
- false_message: &str,
- true_hint: impl FnOnce(Sugg<'_>) -> Sugg<'_>,
- false_hint: impl FnOnce(Sugg<'_>) -> Sugg<'_>,
+ 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::*;
if let ExprKind::Binary(_, ref left_side, ref right_side) = e.node {
- let applicability = Applicability::MachineApplicable;
- match (fetch_bool_expr(left_side), fetch_bool_expr(right_side)) {
- (Bool(true), Other) => suggest_bool_comparison(cx, e, right_side, applicability, true_message, true_hint),
- (Other, Bool(true)) => suggest_bool_comparison(cx, e, left_side, applicability, true_message, true_hint),
- (Bool(false), Other) => {
- suggest_bool_comparison(cx, e, right_side, applicability, false_message, false_hint)
- },
- (Other, Bool(false)) => suggest_bool_comparison(cx, e, left_side, applicability, false_message, false_hint),
- _ => (),
+ let (l_ty, r_ty) = (cx.tables.expr_ty(left_side), cx.tables.expr_ty(right_side));
+ if l_ty.is_bool() && r_ty.is_bool() {
+ let mut applicability = Applicability::MachineApplicable;
+ 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)
+ }),
+ (Other, Bool(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)| {
+ suggest_bool_comparison(cx, e, right_side, applicability, m, h)
+ }),
+ (Other, Bool(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)| {
+ 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(
+ cx,
+ BOOL_COMPARISON,
+ e.span,
+ m,
+ "try simplifying it as shown",
+ h(left_side, right_side).to_string(),
+ applicability,
+ )
+ }),
+ _ => (),
+ }
}
}
}
expr: &Expr,
mut applicability: Applicability,
message: &str,
- conv_hint: impl FnOnce(Sugg<'_>) -> Sugg<'_>,
+ conv_hint: impl FnOnce(Sugg<'a>) -> Sugg<'a>,
) {
let hint = Sugg::hir_with_applicability(cx, expr, "..", &mut applicability);
span_lint_and_sugg(
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 StmtKind::Semi(ref e) = e.node {
if let ExprKind::Ret(_) = e.node {
fetch_bool_expr(&**e)
} else {
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