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Detect comparisons with NAN constants #4910

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Merged
merged 2 commits into from
Dec 18, 2019
Merged

Detect comparisons with NAN constants #4910

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eb0408e
Detect comparisons with NAN constants
krishna-veerareddy Dec 18, 2019
460d5a3
Prevent `cmp_nan` when inside constants
krishna-veerareddy Dec 18, 2019
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26 changes: 15 additions & 11 deletions clippy_lints/src/misc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
}
Expand Down Expand Up @@ -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",
);
}
Expand Down
15 changes: 15 additions & 0 deletions tests/ui/cmp_nan.rs
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Original file line number Diff line number Diff line change
@@ -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() {
Expand All @@ -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;
Expand All @@ -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 changes: 85 additions & 13 deletions tests/ui/cmp_nan.stderr
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Original file line number Diff line number Diff line change
@@ -1,76 +1,148 @@
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;
| ^^^^^^^^^^^^^^^^^^
|
= 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