Rust error E0618: expected function, found

What rustc prints

error[E0618]: expected function, found enum variant `X::Entry`
 --> main.rs:7:1
  |
4 |     Entry,
  |     ----- enum variant `X::Entry` defined here
...
7 | X::Entry(); // error: expected function, tuple struct or tuple variant,
  | ^^^^^^^^--
  | |
  | call expression requires function
  |
help: `X::Entry` is a unit enum variant, and does not take parentheses to be constructed
  |
7 - X::Entry(); // error: expected function, tuple struct or tuple variant,
7 + X::Entry; // error: expected function, tuple struct or tuple variant,
  |

Real output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.

Why it happens

• Calling a unit variant: State::Idle().
• A local variable shadows a function with the same name.

How to fix it

let s = State::Idle;

let total_count = count(&items);  // not let count = count(&items) then count(...)

Other wordings of this error

expected function, found, call expression requires function

enum X {
    Entry,
}

X::Entry(); // error: expected function, tuple struct or tuple variant,
            // found `X::Entry`

// Or even simpler:
let x = 0i32;
x(); // error: expected function, tuple struct or tuple variant, found `i32`

// We declare a function:
fn i_am_a_function() {}

// And we call it:
i_am_a_function();

Related errors

• E0061this function takes N arguments but M were supplied
• E0412cannot find type in this scope
• E0515cannot return reference to local variable
• E0728await is only allowed inside async functions and blocks
• E0605non-primitive cast
• E0606casting `&u8` as `u32` is invalid
• E0627yield expression outside of coroutine literal
• E0628too many parameters for a coroutine (expected 0 or 1 parameters)

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