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Fix suboptimal_float not linting on {const}.powf({const}) #9404

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merged 1 commit into from
Sep 1, 2022
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Fix suboptimal_float not linting on {const}.powf({const}) #9404

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30 changes: 15 additions & 15 deletions clippy_lints/src/floating_point_arithmetic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -238,23 +238,23 @@ fn get_integer_from_float_constant(value: &Constant) -> Option<i32> {
fn check_powf(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
// Check receiver
if let Some((value, _)) = constant(cx, cx.typeck_results(), &args[0]) {
let method = if F32(f32_consts::E) == value || F64(f64_consts::E) == value {
"exp"
if let Some(method) = if F32(f32_consts::E) == value || F64(f64_consts::E) == value {
Some("exp")
} else if F32(2.0) == value || F64(2.0) == value {
"exp2"
Some("exp2")
} else {
return;
};

span_lint_and_sugg(
cx,
SUBOPTIMAL_FLOPS,
expr.span,
"exponent for bases 2 and e can be computed more accurately",
"consider using",
format!("{}.{}()", prepare_receiver_sugg(cx, &args[1]), method),
Applicability::MachineApplicable,
);
None
} {
span_lint_and_sugg(
cx,
SUBOPTIMAL_FLOPS,
expr.span,
"exponent for bases 2 and e can be computed more accurately",
"consider using",
format!("{}.{}()", prepare_receiver_sugg(cx, &args[1]), method),
Applicability::MachineApplicable,
);
}
}

// Check argument
Expand Down
5 changes: 5 additions & 0 deletions tests/ui/floating_point_powf.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,11 @@ fn main() {
let _ = x.powi(-16_777_215);
let _ = (x as f32).powi(-16_777_215);
let _ = (x as f32).powi(3);
let _ = (1.5_f32 + 1.0).cbrt();
let _ = 1.5_f64.cbrt();
let _ = 1.5_f64.sqrt();
let _ = 1.5_f64.powi(3);

// Cases where the lint shouldn't be applied
let _ = x.powf(2.1);
let _ = x.powf(-2.1);
Expand Down
5 changes: 5 additions & 0 deletions tests/ui/floating_point_powf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,11 @@ fn main() {
let _ = x.powf(-16_777_215.0);
let _ = (x as f32).powf(-16_777_215.0);
let _ = (x as f32).powf(3.0);
let _ = (1.5_f32 + 1.0).powf(1.0 / 3.0);
let _ = 1.5_f64.powf(1.0 / 3.0);
let _ = 1.5_f64.powf(1.0 / 2.0);
let _ = 1.5_f64.powf(3.0);

// Cases where the lint shouldn't be applied
let _ = x.powf(2.1);
let _ = x.powf(-2.1);
Expand Down
50 changes: 37 additions & 13 deletions tests/ui/floating_point_powf.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -92,77 +92,101 @@ error: exponentiation with integer powers can be computed more efficiently
LL | let _ = (x as f32).powf(3.0);
| ^^^^^^^^^^^^^^^^^^^^ help: consider using: `(x as f32).powi(3)`

error: cube-root of a number can be computed more accurately
--> $DIR/floating_point_powf.rs:21:13
|
LL | let _ = (1.5_f32 + 1.0).powf(1.0 / 3.0);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `(1.5_f32 + 1.0).cbrt()`

error: cube-root of a number can be computed more accurately
--> $DIR/floating_point_powf.rs:22:13
|
LL | let _ = 1.5_f64.powf(1.0 / 3.0);
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1.5_f64.cbrt()`

error: square-root of a number can be computed more efficiently and accurately
--> $DIR/floating_point_powf.rs:23:13
|
LL | let _ = 1.5_f64.powf(1.0 / 2.0);
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1.5_f64.sqrt()`

error: exponentiation with integer powers can be computed more efficiently
--> $DIR/floating_point_powf.rs:24:13
|
LL | let _ = 1.5_f64.powf(3.0);
| ^^^^^^^^^^^^^^^^^ help: consider using: `1.5_f64.powi(3)`

error: exponent for bases 2 and e can be computed more accurately
--> $DIR/floating_point_powf.rs:28:13
--> $DIR/floating_point_powf.rs:33:13
|
LL | let _ = 2f64.powf(x);
| ^^^^^^^^^^^^ help: consider using: `x.exp2()`

error: exponent for bases 2 and e can be computed more accurately
--> $DIR/floating_point_powf.rs:29:13
--> $DIR/floating_point_powf.rs:34:13
|
LL | let _ = 2f64.powf(3.1);
| ^^^^^^^^^^^^^^ help: consider using: `3.1f64.exp2()`

error: exponent for bases 2 and e can be computed more accurately
--> $DIR/floating_point_powf.rs:30:13
--> $DIR/floating_point_powf.rs:35:13
|
LL | let _ = 2f64.powf(-3.1);
| ^^^^^^^^^^^^^^^ help: consider using: `(-3.1f64).exp2()`

error: exponent for bases 2 and e can be computed more accurately
--> $DIR/floating_point_powf.rs:31:13
--> $DIR/floating_point_powf.rs:36:13
|
LL | let _ = std::f64::consts::E.powf(x);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.exp()`

error: exponent for bases 2 and e can be computed more accurately
--> $DIR/floating_point_powf.rs:32:13
--> $DIR/floating_point_powf.rs:37:13
|
LL | let _ = std::f64::consts::E.powf(3.1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `3.1f64.exp()`

error: exponent for bases 2 and e can be computed more accurately
--> $DIR/floating_point_powf.rs:33:13
--> $DIR/floating_point_powf.rs:38:13
|
LL | let _ = std::f64::consts::E.powf(-3.1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `(-3.1f64).exp()`

error: square-root of a number can be computed more efficiently and accurately
--> $DIR/floating_point_powf.rs:34:13
--> $DIR/floating_point_powf.rs:39:13
|
LL | let _ = x.powf(1.0 / 2.0);
| ^^^^^^^^^^^^^^^^^ help: consider using: `x.sqrt()`

error: cube-root of a number can be computed more accurately
--> $DIR/floating_point_powf.rs:35:13
--> $DIR/floating_point_powf.rs:40:13
|
LL | let _ = x.powf(1.0 / 3.0);
| ^^^^^^^^^^^^^^^^^ help: consider using: `x.cbrt()`

error: exponentiation with integer powers can be computed more efficiently
--> $DIR/floating_point_powf.rs:36:13
--> $DIR/floating_point_powf.rs:41:13
|
LL | let _ = x.powf(3.0);
| ^^^^^^^^^^^ help: consider using: `x.powi(3)`

error: exponentiation with integer powers can be computed more efficiently
--> $DIR/floating_point_powf.rs:37:13
--> $DIR/floating_point_powf.rs:42:13
|
LL | let _ = x.powf(-2.0);
| ^^^^^^^^^^^^ help: consider using: `x.powi(-2)`

error: exponentiation with integer powers can be computed more efficiently
--> $DIR/floating_point_powf.rs:38:13
--> $DIR/floating_point_powf.rs:43:13
|
LL | let _ = x.powf(-2_147_483_648.0);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(-2_147_483_648)`

error: exponentiation with integer powers can be computed more efficiently
--> $DIR/floating_point_powf.rs:39:13
--> $DIR/floating_point_powf.rs:44:13
|
LL | let _ = x.powf(2_147_483_647.0);
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(2_147_483_647)`

error: aborting due to 27 previous errors
error: aborting due to 31 previous errors