src/test/ui/feature-gates/feature-gate-repr-simd.rs

#[repr(simd)] //~ error: SIMD types are experimental
struct Foo(u64, u64);

#[repr(C)] //~ ERROR conflicting representation hints
//~^ WARN this was previously accepted
#[repr(simd)] //~ error: SIMD types are experimental
struct Bar(u64, u64);

fn main() {}