mirror of https://github.com/rust-lang/rust
34 lines
973 B
Rust
34 lines
973 B
Rust
//@ run-pass
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#![allow(dead_code)]
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/*!
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* C-like enums have to be represented as LLVM ints, not wrapped in a
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* struct, because it's important for the FFI that they interoperate
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* with C integers/enums, and the ABI can treat structs differently.
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* For example, on i686-linux-gnu, a struct return value is passed by
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* storing to a hidden out parameter, whereas an integer would be
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* returned in a register.
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*
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* This test just checks that the ABIs for the enum and the plain
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* integer are compatible, rather than actually calling C code.
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* The unused parameter to `foo` is to increase the likelihood of
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* crashing if something goes wrong here.
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*/
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#[repr(u32)]
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enum Foo {
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A = 0,
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B = 23
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}
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#[inline(never)]
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extern "C" fn foo(_x: usize) -> Foo { Foo::B }
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pub fn main() {
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unsafe {
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let f: extern "C" fn(usize) -> u32 =
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::std::mem::transmute(foo as extern "C" fn(usize) -> Foo);
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assert_eq!(f(0xDEADBEEF), Foo::B as u32);
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}
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}
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