Rust errors / Names, paths and imports
Rust compiler error · checked with rustc 1.99.0
Rust error E0423: cannot find function, tuple struct or tuple variant `Foo` in this scope
What it meansAn identifier was used like a function name or a value was expected and the identifier exists but it belongs to a different namespace.
What rustc prints
error[E0423]: cannot find function, tuple struct or tuple variant `Foo` in this scope --> main.rs:5:9 | 3 | struct Foo { a: bool }; | ---------------------- `Foo` defined here 4 | 5 | let f = Foo(); | ^^^^^ help: use struct literal syntax instead: `Foo { a: val }` | = note: a struct named `Foo` exists in another namespace
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.
The compiler team's explanation
An identifier was used like a function name or a value was expected and the identifier exists but it belongs to a different namespace.
Erroneous code example:
struct Foo { a: bool };
let f = Foo();
// error: expected function, tuple struct or tuple variant, found `Foo`
// `Foo` is a struct name, but this expression uses it like a function namePlease verify you didn't misspell the name of what you actually wanted to use here. Example:
fn Foo() -> u32 { 0 }
let f = Foo(); // ok!It is common to forget the trailing ! on macro invocations, which would also yield this error:
println("");
// error: expected function, tuple struct or tuple variant,
// found macro `println`
// did you mean `println!(...)`? (notice the trailing `!`)Another case where this error is emitted is when a value is expected, but something else is found:
pub mod a {
pub const I: i32 = 1;
}
fn h1() -> i32 {
a.I
//~^ ERROR expected value, found module `a`
// did you mean `a::I`?
}Enum types used as values
Enums are types and cannot be used directly as values.
fn main(){
let x = Option::<i32>;
//~^ ERROR expected value,found enum `Option`
}From rustc --explain E0423 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
Related errors
Up next
Often hit nextE0425: cannot find value in this scopeA related error from the same family.Read it next →Did this answer your question?