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// Test that we correctly infer variance for region parameters in
// various self-contained types.
#![feature(rustc_attrs)]
// Regions that just appear in normal spots are contravariant:
#[rustc_variance]
struct Test2<'a, 'b, 'c> { //~ ERROR [-, -, -]
x: &'a isize,
y: &'b [isize],
c: &'c str
}
// Those same annotations in function arguments become covariant:
#[rustc_variance]
struct Test3<'a, 'b, 'c> { //~ ERROR [+, +, +]
x: extern "Rust" fn(&'a isize),
y: extern "Rust" fn(&'b [isize]),
c: extern "Rust" fn(&'c str),
}
// Mutability induces invariance:
#[rustc_variance]
struct Test4<'a, 'b:'a> { //~ ERROR [-, o]
x: &'a mut &'b isize,
}
// Mutability induces invariance, even when in a
// contravariant context:
#[rustc_variance]
struct Test5<'a, 'b:'a> { //~ ERROR [+, o]
x: extern "Rust" fn(&'a mut &'b isize),
}
// Invariance is a trap from which NO ONE CAN ESCAPE.
// In other words, even though the `&'b isize` occurs in
// an argument list (which is contravariant), that
// argument list occurs in an invariant context.
#[rustc_variance]
struct Test6<'a, 'b:'a> { //~ ERROR [-, o]
x: &'a mut extern "Rust" fn(&'b isize),
}
// No uses at all is bivariant:
#[rustc_variance]
struct Test7<'a> { //~ ERROR [*]
x: isize
}
// Try enums too.
#[rustc_variance]
enum Test8<'a, 'b, 'c:'b> { //~ ERROR [+, -, o]
Test8A(extern "Rust" fn(&'a isize)),
Test8B(&'b [isize]),
Test8C(&'b mut &'c str),
}
fn main() {}
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