Rust Error E0788: Incorrect Usage of #[no_coverage] Attribute

Understanding Rust Error E0788

Rust Error E0788 occurs when the #[no_coverage] attribute is applied to an unsupported element, such as structs, consts, or something too granular to be excluded from the coverage report.

Analyzing Rust Error E0788

The #[no_coverage] attribute is used to exclude a piece of code from coverage instrumentation when the -C instrument-coverage flag is passed. However, it can currently only be applied to functions, methods, and closures. Applying it to other elements, such as structs or consts, causes Error E0788.

Error E0788 Example

```rust
#![allow(unused)]
fn main() {
#[no_coverage]
struct Foo;

#[no_coverage]
const FOO: Foo = Foo;
}
```

In the example above, the #[no_coverage] attribute is incorrectly applied to both a struct and a const, triggering Rust Error E0788.

How to Fix Rust Error E0788

To fix Rust Error E0788, remove the #[no_coverage] attribute from any unsupported elements. To apply the attribute to multiple methods in a module, manually annotate each method. Annotating an entire module with a #[no_coverage] attribute is currently not possible.

Fixed Example

```rust
#![allow(unused)]
fn main() {
struct Foo;
const FOO: Foo = Foo;

#[no_coverage]
fn example_function() {
// Function code
}
}```

In the fixed example, the #[no_coverage] attribute has been removed from the struct and const, and applied only to a function.