Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0512: cannot transmute between types of different sizes, or dependently-sized types
What it meansTransmute with two differently sized types was attempted.
What rustc prints
error[E0512]: cannot transmute between types of different sizes, or dependently-sized types --> main.rs:4:23 | 4 | unsafe { takes_u8(::std::mem::transmute(0u16)); } | ^^^^^^^^^^^^^^^^^^^^^ | = note: source type: `u16` (16 bits) = note: target type: `u8` (8 bits)
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.
E0512Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
Transmute with two differently sized types was attempted.
Erroneous code example:
fn takes_u8(_: u8) {}
fn main() {
unsafe { takes_u8(::std::mem::transmute(0u16)); }
// error: cannot transmute between types of different sizes,
// or dependently-sized types
}Please use types with same size or use the expected type directly. Example:
fn takes_u8(_: u8) {}
fn main() {
unsafe { takes_u8(::std::mem::transmute(0i8)); } // ok!
// or:
unsafe { takes_u8(0u8); } // ok!
}From rustc --explain E0512 (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
- E0446private type `Bar` in public interface
- E0449visibility qualifiers are not permitted here
- E0520`fly` specializes an item from a parent `impl`, but that item is not marked `default`
- E0525expected a closure that implements the `Fn` trait, but this closure only implements `FnOnce`
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?