Understanding Rust Error E0736
Introduction to Rust Error E0736
Rust Error E0736 occurs when you attempt to use both #[naked] and #[track_caller] attributes on the same function. This error results from the incompatibility of the two attributes with respect to ABI (Application Binary Interface).
Examining the Error
Let's take a look at an example of the erroneous code:
#![allow(unused)]
fn main() {
#[naked]
#[track_caller]
fn foo() {}
}In this example, the function 'foo()' has both #[naked] and #[track_caller] applied to it, which causes Rust Error E0736 to be thrown. To understand why this error occurs, let's first explore the purpose and usage of each attribute.
Understanding #[naked] and #[track_caller]
The #[naked] attribute is used to specify that a function uses a custom ABI, stripping it of the default prologue and epilogue. This allows for lower-level control over the generated assembly code. #[naked] is typically used for tasks such as interrupt handlers.
Conversely, the #[track_caller] attribute is used to enable more informative panic messages by preserving the accurate caller information for a function. When a function that is tagged with #[track_caller] panics, the panic message will contain information about the original caller, even if the panic originates several calls down the function chain.
Resolving the Error
Since #[naked] disables the prologue and epilogue involved in function calling, it directly conflicts with #[track_caller]'s purpose of preserving caller information. To resolve this error, you need to remove one of the conflicting attributes.
For example, if you only need the #[naked] attribute, update the 'foo()' function as follows:
#![allow(unused)]
fn main() {
#[naked]
fn foo() {}
}Or, if you only need the #[track_caller] attribute, modify the function like this:
#![allow(unused)]
fn main() {
#[track_caller]
fn foo() {}
}