Confusing errors for call_method(arg_name: value) when value is not a literal

[asquared31415]

Given the following code:

Playground

fn uwu(val: i32) {}

fn main() {
    let x = 1_i32;
    uwu(val: x);
}

The current output is:

error[E0425]: cannot find value `val` in this scope
 --> src/main.rs:5:9
  |
5 |     uwu(val: x);
  |         ^^^ expecting a type here because of type ascription

error[E0573]: expected type, found local variable `x`
 --> src/main.rs:5:14
  |
5 |     uwu(val: x);
  |              ^ expecting a type here because of type ascription

Ideally the output should look like it does when value is a literal, like an integer, float, or string literal

error: invalid `struct` delimiters or `fn` call arguments
 --> src/main.rs:5:5
  |
5 |     uwu(val: x);
  |     ^^^^^^^^^^^^^^^
  |
help: if `uwu` is a struct, use braces as delimiters
  |
5 |     uwu { val: x };
  |         ~        ~
help: if `uwu` is a function, use the arguments directly
  |
5 -     uwu(val: x);
5 +     uwu(x);
  |

Diagnostics reproduce on all of current stable, beta, and nightly:
Stable 1.66.0
Beta 1.67.0-beta.2
Nightly 1.68.0 2022-12-15

[Noratrieb]

No one should attempt to fix this until my PR where I remove type ascription.

[fmease]

Unblocked by #109128.

@rustbot label -S-blocked

[jieyouxu]

On beta it seems to be fixed?

error: invalid `struct` delimiters or `fn` call arguments
 --> test.rs:5:5
  |
5 |     uwu(val: x);
  |     ^^^^^^^^^^^
  |
help: if `uwu` is a struct, use braces as delimiters
  |
5 |     uwu { val: x };
  |         ~        ~
help: if `uwu` is a function, use the arguments directly
  |
5 -     uwu(val: x);
5 +     uwu(x);
  |

error: aborting due to previous error

rustc 1.71.0-beta.1 (eff24c06d 2023-05-29)
binary: rustc
commit-hash: eff24c06d8f4397802b546aa2e52450e1022fc02
commit-date: 2023-05-29
host: x86_64-unknown-linux-gnu
release: 1.71.0-beta.1
LLVM version: 16.0.4

[Noratrieb]

Tests:

rust/tests/ui/parser/recover-from-bad-variant.rs

Line 8 in 617d3d6

//~^ ERROR invalid `struct` delimiters or `fn` call arguments

rust/tests/ui/parser/issues/issue-111416.rs

Line 2 in 617d3d6

let my = monad_bind(mx, T: Try); //~ ERROR invalid `struct` delimiters or `fn` call arguments

rust/tests/ui/parser/issues/issue-34255-1.rs

Line 7 in 617d3d6

fn main() {