# Error code E0536

The `not` cfg-predicate was malformed.

Erroneous code example:

    #[cfg(not())] // error: expected 1 cfg-pattern
    pub fn something() {}

    pub fn main() {}

The `not` predicate expects one cfg-pattern. Example:

    #[cfg(not(target_os = "linux"))] // ok!
    pub fn something() {}

    pub fn main() {}

For more information about the `cfg` attribute, read the section on Conditional Compilation in the Reference.