rust-lang / rust-lang/rust

Nested argument mismatch could suggest moving extra parameter outside parenthesis

Open
#124,691 4 comments 1 reaction 1 assignee View on GitHub

Nobody has claimed this yet.

A-diagnostics T-compiler
Dominant language
Rust
Stars
119k
Forks
16.1k
PR merge metrics
PR metrics pending

Description

Code

playground

fn mul(a: i32, b: i32) -> i32 {
    a * b
}

fn main() {
    let x = mul(4.min(3, 14));
    println!("{x}");
}
Current output
Compiling playground v0.0.1 (/playground)
error[E0061]: this method takes 1 argument but 2 arguments were supplied
   --> src/main.rs:6:19
    |
6   |     let x = mul(4.min(3, 14));
    |                   ^^^  ----
    |                        | |
    |                        | unexpected argument of type `{integer}`
    |                        help: remove the extra argument
    |
note: method defined here
   --> /playground/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/cmp.rs:877:8
    |
877 |     fn min(self, other: Self) -> Self
    |        ^^^

error[E0061]: this function takes 2 arguments but 1 argument was supplied
 --> src/main.rs:6:13
  |
6 |     let x = mul(4.min(3, 14));
  |             ^^^-------------- an argument of type `i32` is missing
  |
note: function defined here
 --> src/main.rs:1:4
  |
1 | fn mul(a: i32, b: i32) -> i32 {
  |    ^^^ ------  ------
help: provide the argument
  |
6 |     let x = mul(4.min(3, 14), /* i32 */);
  |                ~~~~~~~~~~~~~~~~~~~~~~~~~

For more information about this error, try `rustc --explain E0061`.
error: could not compile `playground` (bin "playground") due to 2 previous errors
Desired output

Something like

6   |     let x = mul(4.min(3), 14);
    |                   ^^^  ~~~~~
    |                        |
    |                        |
    |                        help: move the argument outside the parenthesis
Rationale and extra context

This happened while trying to pass a missing parameter to an outer function, but I had placed the extra parameter to a call inside instead. When both of the conditions are met, we can be mostly sure that the user intended to pass the parameter to the outer function instead:

  • The inner function/method expects at least one argument and the user passed in an extra one
  • The function call is the last passed in argument to the outer function, but outer function expects one additional argument.
  • The type matches (not sure if possible to check that, but that would make it 100% sure that this is what the user intended)
Other cases

No response

Rust Version
Latest nightly
Anything else?

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.