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Auto merge of #4910 - krishna-veerareddy:issue-1205-cmp-nan-against-consts, r=phansch

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Detect comparisons with NAN constants

Currently `cmp_nan` lint doesn't detect comparisons with NaN's if the operands are consts variables so to fix this we evaluate the const variables first before testing for NaN.

changelog: Detect comparisons with NaN constants in `cmp_nan` lint

Fixes #1205
This commit is contained in:
bors 2019-12-18 20:35:09 +00:00
commit d7c7056a48
3 changed files with 115 additions and 24 deletions
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26
clippy_lints/src/misc.rs
View File

@ -343,12 +343,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MiscLints {
ExprKind::Binary(ref cmp, ref left, ref right) => {
let op = cmp.node;
if op.is_comparison() {
if let ExprKind::Path(QPath::Resolved(_, ref path)) = left.kind {
check_nan(cx, path, expr);
}
if let ExprKind::Path(QPath::Resolved(_, ref path)) = right.kind {
check_nan(cx, path, expr);
}
check_nan(cx, left, expr);
check_nan(cx, right, expr);
check_to_owned(cx, left, right);
check_to_owned(cx, right, left);
}
@ -444,14 +440,22 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MiscLints {
}
}
fn check_nan(cx: &LateContext<'_, '_>, path: &Path, expr: &Expr) {
if !in_constant(cx, expr.hir_id) {
if let Some(seg) = path.segments.last() {
if seg.ident.name == sym!(NAN) {
fn check_nan(cx: &LateContext<'_, '_>, expr: &Expr, cmp_expr: &Expr) {
if_chain! {
if !in_constant(cx, cmp_expr.hir_id);
if let Some((value, _)) = constant(cx, cx.tables, expr);
then {
let needs_lint = match value {
Constant::F32(num) => num.is_nan(),
Constant::F64(num) => num.is_nan(),
_ => false,
};
if needs_lint {
span_lint(
cx,
CMP_NAN,
expr.span,
cmp_expr.span,
"doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead",
);
}

15
tests/ui/cmp_nan.rs
View File

@ -1,3 +1,6 @@
const NAN_F32: f32 = std::f32::NAN;
const NAN_F64: f64 = std::f64::NAN;
#[warn(clippy::cmp_nan)]
#[allow(clippy::float_cmp, clippy::no_effect, clippy::unnecessary_operation)]
fn main() {
@ -8,6 +11,12 @@ fn main() {
x > std::f32::NAN;
x <= std::f32::NAN;
x >= std::f32::NAN;
x == NAN_F32;
x != NAN_F32;
x < NAN_F32;
x > NAN_F32;
x <= NAN_F32;
x >= NAN_F32;
let y = 0f64;
y == std::f64::NAN;
@ -16,4 +25,10 @@ fn main() {
y > std::f64::NAN;
y <= std::f64::NAN;
y >= std::f64::NAN;
y == NAN_F64;
y != NAN_F64;
y < NAN_F64;
y > NAN_F64;
y <= NAN_F64;
y >= NAN_F64;
}

98
tests/ui/cmp_nan.stderr
View File

@ -1,5 +1,5 @@
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:5:5
--> $DIR/cmp_nan.rs:8:5
|
LL | x == std::f32::NAN;
| ^^^^^^^^^^^^^^^^^^
@ -7,70 +7,142 @@ LL | x == std::f32::NAN;
= note: `-D clippy::cmp-nan` implied by `-D warnings`
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:6:5
--> $DIR/cmp_nan.rs:9:5
|
LL | x != std::f32::NAN;
| ^^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:7:5
--> $DIR/cmp_nan.rs:10:5
|
LL | x < std::f32::NAN;
| ^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:8:5
--> $DIR/cmp_nan.rs:11:5
|
LL | x > std::f32::NAN;
| ^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:9:5
--> $DIR/cmp_nan.rs:12:5
|
LL | x <= std::f32::NAN;
| ^^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:10:5
--> $DIR/cmp_nan.rs:13:5
|
LL | x >= std::f32::NAN;
| ^^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:13:5
--> $DIR/cmp_nan.rs:14:5
|
LL | x == NAN_F32;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:15:5
|
LL | x != NAN_F32;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:16:5
|
LL | x < NAN_F32;
| ^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:17:5
|
LL | x > NAN_F32;
| ^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:18:5
|
LL | x <= NAN_F32;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:19:5
|
LL | x >= NAN_F32;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:22:5
|
LL | y == std::f64::NAN;
| ^^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:14:5
--> $DIR/cmp_nan.rs:23:5
|
LL | y != std::f64::NAN;
| ^^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:15:5
--> $DIR/cmp_nan.rs:24:5
|
LL | y < std::f64::NAN;
| ^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:16:5
--> $DIR/cmp_nan.rs:25:5
|
LL | y > std::f64::NAN;
| ^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:17:5
--> $DIR/cmp_nan.rs:26:5
|
LL | y <= std::f64::NAN;
| ^^^^^^^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:18:5
--> $DIR/cmp_nan.rs:27:5
|
LL | y >= std::f64::NAN;
| ^^^^^^^^^^^^^^^^^^
error: aborting due to 12 previous errors
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:28:5
|
LL | y == NAN_F64;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:29:5
|
LL | y != NAN_F64;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:30:5
|
LL | y < NAN_F64;
| ^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:31:5
|
LL | y > NAN_F64;
| ^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:32:5
|
LL | y <= NAN_F64;
| ^^^^^^^^^^^^
error: doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead
--> $DIR/cmp_nan.rs:33:5
|
LL | y >= NAN_F64;
| ^^^^^^^^^^^^
error: aborting due to 24 previous errors