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Prevent incorrect cast_lossless suggestion in const_fn

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`::from` is not a const fn, so applying the suggestion of
`cast_lossless` would fail to compile. The fix is to skip the lint if
the cast is found inside a const fn.
This commit is contained in:
Philipp Hansch 2019-01-26 09:49:55 +01:00
parent f1753522d8
commit 8c416c3197
No known key found for this signature in database
GPG Key ID: B6FA06A6E0E2665B
7 changed files with 72 additions and 36 deletions
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4
clippy_lints/src/utils/mod.rs
View File

@ -82,6 +82,10 @@ pub fn in_constant(cx: &LateContext<'_, '_>, id: NodeId) -> bool {
node: ItemKind::Static(..),
..
}) => true,
Node::Item(&Item {
node: ItemKind::Fn(_, header, ..),
..
}) => header.constness == Constness::Const,
_ => false,
}
}

12
tests/ui/cast_lossless_float.fixed
View File

@ -1,7 +1,8 @@
// run-rustfix
#[warn(clippy::cast_lossless)]
#[allow(clippy::no_effect, clippy::unnecessary_operation)]
#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code)]
#![warn(clippy::cast_lossless)]
fn main() {
// Test clippy::cast_lossless with casts to floating-point types
f32::from(1i8);
@ -15,3 +16,10 @@ fn main() {
f64::from(1i32);
f64::from(1u32);
}
// The lint would suggest using `f64::from(input)` here but the `XX::from` function is not const,
// so we skip the lint if the expression is in a const fn.
// See #3656
const fn abc(input: f32) -> f64 {
input as f64
}

12
tests/ui/cast_lossless_float.rs
View File

@ -1,7 +1,8 @@
// run-rustfix
#[warn(clippy::cast_lossless)]
#[allow(clippy::no_effect, clippy::unnecessary_operation)]
#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code)]
#![warn(clippy::cast_lossless)]
fn main() {
// Test clippy::cast_lossless with casts to floating-point types
1i8 as f32;
@ -15,3 +16,10 @@ fn main() {
1i32 as f64;
1u32 as f64;
}
// The lint would suggest using `f64::from(input)` here but the `XX::from` function is not const,
// so we skip the lint if the expression is in a const fn.
// See #3656
const fn abc(input: f32) -> f64 {
input as f64
}

20
tests/ui/cast_lossless_float.stderr
View File

@ -1,5 +1,5 @@
error: casting i8 to f32 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:7:5
--> $DIR/cast_lossless_float.rs:8:5
|
LL | 1i8 as f32;
| ^^^^^^^^^^ help: try: `f32::from(1i8)`
@ -7,55 +7,55 @@ LL | 1i8 as f32;
= note: `-D clippy::cast-lossless` implied by `-D warnings`
error: casting i8 to f64 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:8:5
--> $DIR/cast_lossless_float.rs:9:5
|
LL | 1i8 as f64;
| ^^^^^^^^^^ help: try: `f64::from(1i8)`
error: casting u8 to f32 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:9:5
--> $DIR/cast_lossless_float.rs:10:5
|
LL | 1u8 as f32;
| ^^^^^^^^^^ help: try: `f32::from(1u8)`
error: casting u8 to f64 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:10:5
--> $DIR/cast_lossless_float.rs:11:5
|
LL | 1u8 as f64;
| ^^^^^^^^^^ help: try: `f64::from(1u8)`
error: casting i16 to f32 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:11:5
--> $DIR/cast_lossless_float.rs:12:5
|
LL | 1i16 as f32;
| ^^^^^^^^^^^ help: try: `f32::from(1i16)`
error: casting i16 to f64 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:12:5
--> $DIR/cast_lossless_float.rs:13:5
|
LL | 1i16 as f64;
| ^^^^^^^^^^^ help: try: `f64::from(1i16)`
error: casting u16 to f32 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:13:5
--> $DIR/cast_lossless_float.rs:14:5
|
LL | 1u16 as f32;
| ^^^^^^^^^^^ help: try: `f32::from(1u16)`
error: casting u16 to f64 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:14:5
--> $DIR/cast_lossless_float.rs:15:5
|
LL | 1u16 as f64;
| ^^^^^^^^^^^ help: try: `f64::from(1u16)`
error: casting i32 to f64 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:15:5
--> $DIR/cast_lossless_float.rs:16:5
|
LL | 1i32 as f64;
| ^^^^^^^^^^^ help: try: `f64::from(1i32)`
error: casting u32 to f64 may become silently lossy if types change
--> $DIR/cast_lossless_float.rs:16:5
--> $DIR/cast_lossless_float.rs:17:5
|
LL | 1u32 as f64;
| ^^^^^^^^^^^ help: try: `f64::from(1u32)`

12
tests/ui/cast_lossless_integer.fixed
View File

@ -1,7 +1,8 @@
// run-rustfix
#[warn(clippy::cast_lossless)]
#[allow(clippy::no_effect, clippy::unnecessary_operation)]
#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code)]
#![warn(clippy::cast_lossless)]
fn main() {
// Test clippy::cast_lossless with casts to integer types
i16::from(1i8);
@ -23,3 +24,10 @@ fn main() {
i64::from(1u32);
u64::from(1u32);
}
// The lint would suggest using `f64::from(input)` here but the `XX::from` function is not const,
// so we skip the lint if the expression is in a const fn.
// See #3656
const fn abc(input: u16) -> u32 {
input as u32
}

12
tests/ui/cast_lossless_integer.rs
View File

@ -1,7 +1,8 @@
// run-rustfix
#[warn(clippy::cast_lossless)]
#[allow(clippy::no_effect, clippy::unnecessary_operation)]
#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code)]
#![warn(clippy::cast_lossless)]
fn main() {
// Test clippy::cast_lossless with casts to integer types
1i8 as i16;
@ -23,3 +24,10 @@ fn main() {
1u32 as i64;
1u32 as u64;
}
// The lint would suggest using `f64::from(input)` here but the `XX::from` function is not const,
// so we skip the lint if the expression is in a const fn.
// See #3656
const fn abc(input: u16) -> u32 {
input as u32
}

36
tests/ui/cast_lossless_integer.stderr
View File

@ -1,5 +1,5 @@
error: casting i8 to i16 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:7:5
--> $DIR/cast_lossless_integer.rs:8:5
|
LL | 1i8 as i16;
| ^^^^^^^^^^ help: try: `i16::from(1i8)`
@ -7,103 +7,103 @@ LL | 1i8 as i16;
= note: `-D clippy::cast-lossless` implied by `-D warnings`
error: casting i8 to i32 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:8:5
--> $DIR/cast_lossless_integer.rs:9:5
|
LL | 1i8 as i32;
| ^^^^^^^^^^ help: try: `i32::from(1i8)`
error: casting i8 to i64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:9:5
--> $DIR/cast_lossless_integer.rs:10:5
|
LL | 1i8 as i64;
| ^^^^^^^^^^ help: try: `i64::from(1i8)`
error: casting u8 to i16 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:10:5
--> $DIR/cast_lossless_integer.rs:11:5
|
LL | 1u8 as i16;
| ^^^^^^^^^^ help: try: `i16::from(1u8)`
error: casting u8 to i32 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:11:5
--> $DIR/cast_lossless_integer.rs:12:5
|
LL | 1u8 as i32;
| ^^^^^^^^^^ help: try: `i32::from(1u8)`
error: casting u8 to i64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:12:5
--> $DIR/cast_lossless_integer.rs:13:5
|
LL | 1u8 as i64;
| ^^^^^^^^^^ help: try: `i64::from(1u8)`
error: casting u8 to u16 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:13:5
--> $DIR/cast_lossless_integer.rs:14:5
|
LL | 1u8 as u16;
| ^^^^^^^^^^ help: try: `u16::from(1u8)`
error: casting u8 to u32 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:14:5
--> $DIR/cast_lossless_integer.rs:15:5
|
LL | 1u8 as u32;
| ^^^^^^^^^^ help: try: `u32::from(1u8)`
error: casting u8 to u64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:15:5
--> $DIR/cast_lossless_integer.rs:16:5
|
LL | 1u8 as u64;
| ^^^^^^^^^^ help: try: `u64::from(1u8)`
error: casting i16 to i32 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:16:5
--> $DIR/cast_lossless_integer.rs:17:5
|
LL | 1i16 as i32;
| ^^^^^^^^^^^ help: try: `i32::from(1i16)`
error: casting i16 to i64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:17:5
--> $DIR/cast_lossless_integer.rs:18:5
|
LL | 1i16 as i64;
| ^^^^^^^^^^^ help: try: `i64::from(1i16)`
error: casting u16 to i32 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:18:5
--> $DIR/cast_lossless_integer.rs:19:5
|
LL | 1u16 as i32;
| ^^^^^^^^^^^ help: try: `i32::from(1u16)`
error: casting u16 to i64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:19:5
--> $DIR/cast_lossless_integer.rs:20:5
|
LL | 1u16 as i64;
| ^^^^^^^^^^^ help: try: `i64::from(1u16)`
error: casting u16 to u32 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:20:5
--> $DIR/cast_lossless_integer.rs:21:5
|
LL | 1u16 as u32;
| ^^^^^^^^^^^ help: try: `u32::from(1u16)`
error: casting u16 to u64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:21:5
--> $DIR/cast_lossless_integer.rs:22:5
|
LL | 1u16 as u64;
| ^^^^^^^^^^^ help: try: `u64::from(1u16)`
error: casting i32 to i64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:22:5
--> $DIR/cast_lossless_integer.rs:23:5
|
LL | 1i32 as i64;
| ^^^^^^^^^^^ help: try: `i64::from(1i32)`
error: casting u32 to i64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:23:5
--> $DIR/cast_lossless_integer.rs:24:5
|
LL | 1u32 as i64;
| ^^^^^^^^^^^ help: try: `i64::from(1u32)`
error: casting u32 to u64 may become silently lossy if types change
--> $DIR/cast_lossless_integer.rs:24:5
--> $DIR/cast_lossless_integer.rs:25:5
|
LL | 1u32 as u64;
| ^^^^^^^^^^^ help: try: `u64::from(1u32)`