Closed
Description
openedon Sep 30, 2021
Given the following code: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=5f20683e51f9be844a0cc50aeb746f5d
fn main() {
let option: Option<&[u8]> = Some(b"...");
let _ = option.map([_]::to_vec);
}The current output is:
- it thinks
to_vecis a crate name - it claims that
[_]isn't meaningful because it isn't left of an assignment - it claims that 2 arguments were passed to
map
error: expected one of `)`, `,`, `.`, `?`, or an operator, found `::`
--> src/main.rs:3:27
|
3 | let _ = option.map([_]::to_vec);
| -^
| |
| expected one of `)`, `,`, `.`, `?`, or an operator
| help: missing `,`
error[E0425]: cannot find crate `to_vec` in the list of imported crates
--> src/main.rs:3:29
|
3 | let _ = option.map([_]::to_vec);
| ^^^^^^ not found in the list of imported crates
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> src/main.rs:3:25
|
3 | let _ = option.map([_]::to_vec);
| ^ `_` not allowed here
error[E0061]: this function takes 1 argument but 2 arguments were supplied
--> src/main.rs:3:20
|
3 | let _ = option.map([_]::to_vec);
| ^^^ ----------- supplied 2 arguments
| |
| expected 1 argument
|
note: associated function defined here
--> /media/david/coding/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:843:12
|
843 | pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Option<U> {
| ^^^
Some errors have detailed explanations: E0061, E0425.
For more information about an error, try `rustc --explain E0061`.Ideally the output should look like:
error: missing angle brackets in associated item path
--> src/main.rs:3:24
|
3 | let _ = option.map([_]::to_vec);
| ^^^^^^^^^^^ help: try: `<[_]>::to_vec`Indeed this is exactly that you already get if you had put [u8]::to_vec instead of [_]::to_vec.
fn main() {
let option: Option<&[u8]> = Some(b"...");
let _ = option.map([u8]::to_vec);
}error: missing angle brackets in associated item path
--> src/main.rs:3:24
|
3 | let _ = option.map([u8]::to_vec);
| ^^^^^^^^^^^^ help: try: `<[u8]>::to_vec`Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment