for_loops_over_fallibles lint with macros give invalid suggestion #148114
Description
Code
src/main.rs
fn main() {
let _name = Some(1);
dep::do_loop!(_name);
}dep/src/lib.rs
#[macro_export]
macro_rules! identity {
($x:ident) => {
$x
};
}
#[macro_export]
macro_rules! do_loop {
($x:ident) => {
for $crate::identity!($x) in $x {}
};
}Zip of all files needed for reproduction, for your convenience: repro.zip
Current output
warning: for loop over an `Option`. This is more readably written as an `if let` statement
--> src\main.rs:3:5
|
3 | dep::do_loop!(_name);
| ^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(for_loops_over_fallibles)]` on by default
help: to check pattern in a loop use `while let`
--> C:\Users\theem\Downloads\repro\dep\src\lib.rs:4:9
|
4 ~ while let Some(for $crate::identity!($x) in $x {}
5 ~ ) =
|
help: consider using `if let` to clear intent
--> C:\Users\theem\Downloads\repro\dep\src\lib.rs:4:9
|
4 ~ if let Some(for $crate::identity!($x) in $x {}
5 ~ ) =
|
warning: `repro` (bin "repro") generated 1 warningDesired output
Rationale and extra context
No response
Other cases
Rust Version
rustc 1.90.0 (1159e78c4 2025-09-14)
binary: rustc
commit-hash: 1159e78c4747b02ef996e55082b704c09b970588
commit-date: 2025-09-14
host: x86_64-pc-windows-msvc
release: 1.90.0
LLVM version: 20.1.8Anything else?
Discovered in #147973 as part of a crater run, in which rust gave the invalid suggestion in 1.90.0, but ICE'ed in beta.