equatable-if-let not stable for consts yet #15376
Description
Using the following flags
--force-warn clippy::equatable-if-let
this code:
// check-pass
const _: i32 = if true { 5 } else { 6 };
const _: i32 = if let Some(true) = Some(false) { 0 } else { 1 };
const _: i32 = match 1 {
2 => 3,
4 => 5,
_ => 0,
};
static FOO: i32 = {
let x = if true { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
};
static mut BAR: i32 = {
let x = if true { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
};
const fn if_() -> i32 {
if true { 5 } else { 6 }
}
const fn if_let(a: Option<bool>) -> i32 {
if let Some(true) = a { 0 } else { 1 }
}
const fn match_(i: i32) -> i32 {
match i {
i if i > 10 => i,
1 => 2,
_ => 0,
}
}
pub trait Foo {
const IF: i32 = if true { 5 } else { 6 };
const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
const MATCH: i32 = match 0 {
1 => 2,
_ => 0,
};
}
impl Foo for () {
const IF: i32 = if true { 5 } else { 6 };
const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
const MATCH: i32 = match 0 {
1 => 2,
_ => 0,
};
}
fn non_const_outside() {
const fn const_inside(y: bool) -> i32 {
let x = if y { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
}
}
const fn const_outside() {
fn non_const_inside(y: bool) -> i32 {
let x = if y { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
}
}
fn main() {
let _ = [0; {
let x = if false { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
}];
}caused the following diagnostics:
Checking _25c7d89391ba419647e7c93840343016b186793e v0.1.0 (/tmp/icemaker_global_tempdir.f0JXFBTcO4io/icemaker_clippyfix_tempdir.oAbQxx8YWj6r/_25c7d89391ba419647e7c93840343016b186793e)
warning: this pattern matching can be expressed using equality
--> src/main.rs:5:19
|
5 | const _: i32 = if let Some(true) = Some(false) { 0 } else { 1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Some(false) == Some(true)`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#equatable_if_let
= note: requested on the command line with `--force-warn clippy::equatable-if-let`
warning: this pattern matching can be expressed using equality
--> src/main.rs:36:8
|
36 | if let Some(true) = a { 0 } else { 1 }
| ^^^^^^^^^^^^^^^^^^ help: try: `a == Some(true)`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#equatable_if_let
warning: this pattern matching can be expressed using equality
--> src/main.rs:49:28
|
49 | const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^^^^ help: try: `None == Some(true)`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#equatable_if_let
warning: this pattern matching can be expressed using equality
--> src/main.rs:58:28
|
58 | const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^^^^ help: try: `None == Some(true)`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#equatable_if_let
warning: `_25c7d89391ba419647e7c93840343016b186793e` (bin "_25c7d89391ba419647e7c93840343016b186793e") generated 4 warnings (run `cargo clippy --fix --bin "_25c7d89391ba419647e7c93840343016b186793e"` to apply 4 suggestions)
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.41s
However after applying these diagnostics, the resulting code:
// check-pass
#![feature(const_cmp)]
const _: i32 = if true { 5 } else { 6 };
const _: i32 = if Some(false) == Some(true) { 0 } else { 1 };
const _: i32 = match 1 {
2 => 3,
4 => 5,
_ => 0,
};
static FOO: i32 = {
let x = if true { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
};
static mut BAR: i32 = {
let x = if true { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
};
const fn if_() -> i32 {
if true { 5 } else { 6 }
}
const fn if_let(a: Option<bool>) -> i32 {
if a == Some(true) { 0 } else { 1 }
}
const fn match_(i: i32) -> i32 {
match i {
i if i > 10 => i,
1 => 2,
_ => 0,
}
}
pub trait Foo {
const IF: i32 = if true { 5 } else { 6 };
const IF_LET: i32 = if None == Some(true) { 5 } else { 6 };
const MATCH: i32 = match 0 {
1 => 2,
_ => 0,
};
}
impl Foo for () {
const IF: i32 = if true { 5 } else { 6 };
const IF_LET: i32 = if None == Some(true) { 5 } else { 6 };
const MATCH: i32 = match 0 {
1 => 2,
_ => 0,
};
}
fn non_const_outside() {
const fn const_inside(y: bool) -> i32 {
let x = if y { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
}
}
const fn const_outside() {
fn non_const_inside(y: bool) -> i32 {
let x = if y { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
}
}
fn main() {
let _ = [0; {
let x = if false { 0 } else { 1 };
let x = match x {
0 => 1,
_ => 0,
};
if let Some(x) = Some(x) { x } else { 1 }
}];
}no longer compiled:
Checking _25c7d89391ba419647e7c93840343016b186793e v0.1.0 (/tmp/icemaker_global_tempdir.f0JXFBTcO4io/icemaker_clippyfix_tempdir.oAbQxx8YWj6r/_25c7d89391ba419647e7c93840343016b186793e)
error[E0658]: cannot call conditionally-const operator in constants
--> src/main.rs:6:19
|
6 | const _: i32 = if Some(false) == Some(true) { 0 } else { 1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: calls in constants are limited to constant functions, tuple structs and tuple variants
= note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on 2025-07-31; consider upgrading it if it is out of date
error[E0658]: cannot call conditionally-const operator in constant functions
--> src/main.rs:37:8
|
37 | if a == Some(true) { 0 } else { 1 }
| ^^^^^^^^^^^^^^^
|
= note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
= note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on 2025-07-31; consider upgrading it if it is out of date
error[E0658]: cannot call conditionally-const operator in constants
--> src/main.rs:50:28
|
50 | const IF_LET: i32 = if None == Some(true) { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^
|
= note: calls in constants are limited to constant functions, tuple structs and tuple variants
= note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on 2025-07-31; consider upgrading it if it is out of date
error[E0658]: cannot call conditionally-const operator in constants
--> src/main.rs:59:28
|
59 | const IF_LET: i32 = if None == Some(true) { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^
|
= note: calls in constants are limited to constant functions, tuple structs and tuple variants
= note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
= help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
= note: this compiler was built on 2025-07-31; consider upgrading it if it is out of date
For more information about this error, try `rustc --explain E0658`.
error: could not compile `_25c7d89391ba419647e7c93840343016b186793e` (bin "_25c7d89391ba419647e7c93840343016b186793e" test) due to 4 previous errors
warning: build failed, waiting for other jobs to finish...
error: could not compile `_25c7d89391ba419647e7c93840343016b186793e` (bin "_25c7d89391ba419647e7c93840343016b186793e") due to 4 previous errors
Version:
rustc 1.90.0-nightly (cc0a5b730 2025-07-31)
binary: rustc
commit-hash: cc0a5b73053c62a3df5f84b3ee85079c9b65fa87
commit-date: 2025-07-31
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.8