multiple_unsafe_ops_per_block triggering for format! on nightly #16116
Description
Summary
The following code will trigger clippy::multiple_unsafe_ops_per_block on 1.93.0-nightly (2025-11-17 0df64c57843a9612c68d), but not on stable 1.91.1: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&gist=12e538ea37bfbf81674c74f0ec119fff
format! on its own doesn't require unsafe, so I'm unsure what's causing multiple_unsafe_ops_per_block to fire on nightly for format!.
Lint Name
multiple_unsafe_ops_per_block
Reproducer
I tried this code:
#![forbid(clippy::multiple_unsafe_ops_per_block)]
unsafe fn foo() -> u32 {
0
}
fn main() {
unsafe{
let _ = format!("{}", foo());
}
}I saw this happen:
Checking playground v0.0.1 (/playground)
error: this `unsafe` block contains 2 unsafe operations, expected only one
--> src/main.rs:8:5
|
8 | / unsafe{
9 | | let _ = format!("{}", foo());
10 | | }
| |_____^
|
note: unsafe function call occurs here
--> src/main.rs:9:31
|
9 | let _ = format!("{}", foo());
| ^^^^^
note: unsafe function call occurs here
--> src/main.rs:9:17
|
9 | let _ = format!("{}", foo());
| ^^^^^^^^^^^^^^^^^^^^
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#multiple_unsafe_ops_per_block
note: the lint level is defined here
--> src/main.rs:1:11
|
1 | #![forbid(clippy::multiple_unsafe_ops_per_block)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: this error originates in the macro `format` (in Nightly builds, run with -Z macro-backtrace for more info)
error: could not compile `playground` (bin "playground") due to 1 previous error
I expected to see this happen: successful clippy run
Version
Nightly channel Build using the Nightly version: 1.93.0-nightly (2025-11-17 0df64c57843a9612c68d)
Additional Labels
No response