lotsoftools

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() {}
}