allow-until

Allows an item until a specified semver version, and then errors on compilation.

#[allow_until(version = ">= 1.0.x", reason = "struct is deprecated from version 1.0.x onwards")]
struct MyStruct {
    //....
}

Or with the derive macro:

#[derive(AllowUntil)]
struct MyStruct {
    #[allow_until(version = ">= 1.0.x", reason = "member is deprecated from version 1.0.x onwards")]
    foo: usize
}

Once the CARGO_PKG_VERSION matches the given semver predicate, the macro will cause a compilation error, therefore reminding you to update/remove the code.