rust/src/test/ui/malformed/malformed-special-attrs.rs

#[cfg_attr] //~ ERROR expected `(`, found end of attribute
struct S1;

#[cfg_attr = ""] //~ ERROR expected `(`, found `=`
struct S2;

#[derive] //~ ERROR attribute must be of the form
struct S3;

#[derive = ""] //~ ERROR attribute must be of the form
struct S4;

fn main() {}