Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0791: invalid type for variable with `#[linkage]` attribute
What it meansStatic variables with the #[linkage] attribute within external blocks must have one of the following types, which are equivalent to a nullable pointer in C:
What rustc prints
error[E0791]: invalid type for variable with `#[linkage]` attribute
--> main.rs:5:5
|
5 | static foo: i8;
| ^^^^^^^^^^^^^^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
Static variables with the #[linkage] attribute within external blocks must have one of the following types, which are equivalent to a nullable pointer in C:
*mut Tor*const T, whereTmay be any type.
- An enumerator type with no
#[repr]attribute and with two variants, where one of the variants has no fields, and the other has a single field of one of the following non-nullable types: - Reference type
- Function pointer type
The variants can appear in either order.
For example, the following declaration is invalid:
#![feature(linkage)]
extern "C" {
#[linkage = "extern_weak"]
static foo: i8;
}The following declarations are valid:
#![feature(linkage)]
extern "C" {
#[linkage = "extern_weak"]
static foo: Option<unsafe extern "C" fn()>;
#[linkage = "extern_weak"]
static bar: Option<&'static i8>;
#[linkage = "extern_weak"]
static baz: *mut i8;
}From rustc --explain E0791 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
Related errors
- E0308mismatched types
- E0277the trait bound is not satisfied
- E0599no method named X found in the current scope
- E0433failed to resolve
- E0785cannot define inherent `impl` for a dyn auto trait
- E0790cannot call associated function on trait without specifying the corresponding `impl` type
- E0792expected generic type parameter, found `u32`
- E0799expected type or const parameter, found function `main`
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?