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Merge branch 'pr-645'

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This commit is contained in:
Manish Goregaokar 2016-02-10 10:20:23 +05:30
commit 1013026f18
4 changed files with 102 additions and 2 deletions
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2
src/lib.rs
View file

@ -105,6 +105,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_late_lint_pass(box bit_mask::BitMask);
reg.register_late_lint_pass(box ptr_arg::PtrArg);
reg.register_late_lint_pass(box needless_bool::NeedlessBool);
reg.register_late_lint_pass(box needless_bool::BoolComparison);
reg.register_late_lint_pass(box approx_const::ApproxConstant);
reg.register_late_lint_pass(box misc::FloatCmp);
reg.register_early_lint_pass(box precedence::Precedence);
@ -252,6 +253,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
misc_early::UNNEEDED_FIELD_PATTERN,
mut_reference::UNNECESSARY_MUT_PASSED,
mutex_atomic::MUTEX_ATOMIC,
needless_bool::BOOL_COMPARISON,
needless_bool::NEEDLESS_BOOL,
needless_features::UNSTABLE_AS_MUT_SLICE,
needless_features::UNSTABLE_AS_SLICE,

76
src/needless_bool.rs
View file

@ -6,8 +6,9 @@ use rustc::lint::*;
use rustc_front::hir::*;
use syntax::ast::Lit_;
use syntax::codemap::Spanned;
use utils::{span_lint, snippet};
use utils::{span_lint, span_lint_and_then, snippet};
/// **What it does:** This lint checks for expressions of the form `if c { true } else { false }` (or vice versa) and suggest using the condition directly.
///
@ -23,6 +24,20 @@ declare_lint! {
`if p { true } else { false }`"
}
/// **What it does:** This lint checks for expressions of the form `x == true` (or vice versa) and suggest using the variable directly.
///
/// **Why is this bad?** Unnecessary code.
///
/// **Known problems:** None.
///
/// **Example:** `if x == true { }` could be `if x { }`
declare_lint! {
pub BOOL_COMPARISON,
Warn,
"comparing a variable to a boolean, e.g. \
`if x == true`"
}
#[derive(Copy,Clone)]
pub struct NeedlessBool;
@ -78,6 +93,65 @@ impl LateLintPass for NeedlessBool {
}
}
#[derive(Copy,Clone)]
pub struct BoolComparison;
impl LintPass for BoolComparison {
fn get_lints(&self) -> LintArray {
lint_array!(BOOL_COMPARISON)
}
}
impl LateLintPass for BoolComparison {
fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
if let ExprBinary(Spanned{ node: BiEq, .. }, ref left_side, ref right_side) = e.node {
match (fetch_bool_expr(left_side), fetch_bool_expr(right_side)) {
(Some(true), None) => {
let hint = snippet(cx, right_side.span, "..").into_owned();
span_lint_and_then(cx,
BOOL_COMPARISON,
e.span,
"equality checks against true are unnecesary",
|db| {
db.span_suggestion(e.span, "try simplifying it as shown:", hint);
});
}
(None, Some(true)) => {
let hint = snippet(cx, left_side.span, "..").into_owned();
span_lint_and_then(cx,
BOOL_COMPARISON,
e.span,
"equality checks against true are unnecesary",
|db| {
db.span_suggestion(e.span, "try simplifying it as shown:", hint);
});
}
(Some(false), None) => {
let hint = format!("!{}", snippet(cx, right_side.span, ".."));
span_lint_and_then(cx,
BOOL_COMPARISON,
e.span,
"equality checks against false can be replaced by a negation",
|db| {
db.span_suggestion(e.span, "try simplifying it as shown:", hint);
});
}
(None, Some(false)) => {
let hint = format!("!{}", snippet(cx, left_side.span, ".."));
span_lint_and_then(cx,
BOOL_COMPARISON,
e.span,
"equality checks against false can be replaced by a negation",
|db| {
db.span_suggestion(e.span, "try simplifying it as shown:", hint);
});
}
_ => (),
}
}
}
}
fn fetch_bool_block(block: &Block) -> Option<bool> {
if block.stmts.is_empty() {
block.expr.as_ref().and_then(|e| fetch_bool_expr(e))