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Added 'ineffective bit mask' lint

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This commit is contained in:
llogiq 2015-05-15 14:09:29 +02:00
parent 905509083c
commit 6bec4f35df
4 changed files with 50 additions and 10 deletions
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40
src/bit_mask.rs
View file

@ -32,12 +32,18 @@ declare_lint! {
"Deny the use of incompatible bit masks in comparisons, e.g. '(a & 1) == 2'"
}
declare_lint! {
pub INEFFECTIVE_BIT_MASK,
Warn,
"Warn on the use of an ineffective bit mask in comparisons, e.g. '(a & 1) > 2'"
}
#[derive(Copy,Clone)]
pub struct BitMask;
impl LintPass for BitMask {
fn get_lints(&self) -> LintArray {
lint_array!(BAD_BIT_MASK)
lint_array!(BAD_BIT_MASK, INEFFECTIVE_BIT_MASK)
}
fn check_expr(&mut self, cx: &Context, e: &Expr) {
@ -102,31 +108,47 @@ fn check_bit_mask(cx: &Context, bit_op: BinOp_, cmp_op: BinOp_, mask_value: u64,
},
BiLt | BiGe => match bit_op {
BiBitAnd => if mask_value < cmp_value {
cx.span_lint(BAD_BIT_MASK, *span, &format!("incompatible bit mask: _ & {} will always be lower than {}", mask_value,
cmp_value));
cx.span_lint(BAD_BIT_MASK, *span, &format!(
"incompatible bit mask: _ & {} will always be lower than {}",
mask_value, cmp_value));
} else {
if mask_value == 0 {
cx.span_lint(BAD_BIT_MASK, *span, &format!("&-masking with zero"));
}
},
BiBitOr => if mask_value >= cmp_value {
cx.span_lint(BAD_BIT_MASK, *span, &format!("incompatible bit mask: _ | {} will never be lower than {}", mask_value,
cmp_value));
cx.span_lint(BAD_BIT_MASK, *span, &format!(
"incompatible bit mask: _ | {} will never be lower than {}",
mask_value, cmp_value));
} else {
if mask_value < cmp_value {
cx.span_lint(INEFFECTIVE_BIT_MASK, *span, &format!(
"ineffective bit mask: x | {} compared to {} is the same as x compared directly",
mask_value, cmp_value));
}
},
_ => ()
},
BiLe | BiGt => match bit_op {
BiBitAnd => if mask_value <= cmp_value {
cx.span_lint(BAD_BIT_MASK, *span, &format!("incompatible bit mask: _ & {} will never be higher than {}", mask_value,
cmp_value));
cx.span_lint(BAD_BIT_MASK, *span, &format!(
"incompatible bit mask: _ & {} will never be higher than {}",
mask_value, cmp_value));
} else {
if mask_value == 0 {
cx.span_lint(BAD_BIT_MASK, *span, &format!("&-masking with zero"));
}
},
BiBitOr => if mask_value > cmp_value {
cx.span_lint(BAD_BIT_MASK, *span, &format!("incompatible bit mask: _ | {} will always be higher than {}", mask_value,
cmp_value));
cx.span_lint(BAD_BIT_MASK, *span, &format!(
"incompatible bit mask: _ | {} will always be higher than {}",
mask_value, cmp_value));
} else {
if mask_value < cmp_value {
cx.span_lint(INEFFECTIVE_BIT_MASK, *span, &format!(
"ineffective bit mask: x | {} compared to {} is the same as x compared directly",
mask_value, cmp_value));
}
},
_ => ()
},

4
src/lib.rs
View file

@ -42,7 +42,9 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_lint_group("clippy", vec![types::BOX_VEC, types::LINKEDLIST,
misc::SINGLE_MATCH, misc::STR_TO_STRING,
misc::TOPLEVEL_REF_ARG, eq_op::EQ_OP,
bit_mask::BAD_BIT_MASK, ptr_arg::PTR_ARG,
bit_mask::BAD_BIT_MASK,
bit_mask::INEFFECTIVE_BIT_MASK,
ptr_arg::PTR_ARG,
needless_bool::NEEDLESS_BOOL,
approx_const::APPROX_CONSTANT,
misc::CMP_NAN, misc::FLOAT_CMP,