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Suboptimal diagnostic for assert_eq! mistyped as assert! #148476
Description
Code
fn foo(a: i32, b: i32) {
assert!(a, b);
}Current output
error: format argument must be a string literal
--> src/lib.rs:5:16
|
5 | assert!(a, b);
| ^
|
help: you might be missing a string literal to format with
|
5 | assert!(a, "{}", b);
| +++++
error[E0308]: mismatched types
--> src/lib.rs:5:5
|
5 | assert!(a, b);
| ^^^^^^^^^^^^^ expected `bool`, found `i32`Desired output
error: format argument must be a string literal
--> src/lib.rs:5:16
|
5 | assert!(a, b);
| ^
|
help: you might have meant to use `assert_eq!`
|
5 | assert_eq!(a, b);
| +++
error[E0308]: mismatched types
--> src/lib.rs:5:5
|
5 | assert!(a, b);
| ^^^^^^^^^^^^^ expected `bool`, found `i32`Rationale and extra context
When the two arguments have the same types (that is not bool), it's imo more likely that the user meant to use assert_eq!. In my case, this happened when I wanted to change an assert! to assert_eq!, but only replaced == with ,, forgetting to change the name as well.
Other cases
Rust Version
rustc 1.91.0 (f8297e351 2025-10-28)
binary: rustc
commit-hash: f8297e351a40c1439a467bbbb6879088047f50b3
commit-date: 2025-10-28
host: x86_64-unknown-linux-gnu
release: 1.91.0
LLVM version: 21.1.2Anything else?
No response
Activity
fmease commentedon Nov 5, 2025
cc #57507
ada4a commentedon Nov 5, 2025
Looks like a complete duplicate... Sorry, I did try to search through existing issues, but it's a bit hard with keywords like this
assert!(x, y)withassert_eq!(x, y)#57507