diff options
Diffstat (limited to 'compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs')
-rw-r--r-- | compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs b/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs new file mode 100644 index 000000000..2ecc8b823 --- /dev/null +++ b/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs @@ -0,0 +1,59 @@ +// Copied from rustc ui test suite + +// run-pass +// +// Test that we can handle unsized types with an extern type tail part. +// Regression test for issue #91827. + +#![feature(const_ptr_offset_from)] +#![feature(extern_types)] + +use std::ptr::addr_of; + +extern "C" { + type Opaque; +} + +unsafe impl Sync for Opaque {} + +#[repr(C)] +pub struct List<T> { + len: usize, + data: [T; 0], + tail: Opaque, +} + +#[repr(C)] +pub struct ListImpl<T, const N: usize> { + len: usize, + data: [T; N], +} + +impl<T> List<T> { + const fn as_slice(&self) -> &[T] { + unsafe { std::slice::from_raw_parts(self.data.as_ptr(), self.len) } + } +} + +impl<T, const N: usize> ListImpl<T, N> { + const fn as_list(&self) -> &List<T> { + unsafe { std::mem::transmute(self) } + } +} + +pub static A: ListImpl<u128, 3> = ListImpl { + len: 3, + data: [5, 6, 7], +}; +pub static A_REF: &'static List<u128> = A.as_list(); +pub static A_TAIL_OFFSET: isize = tail_offset(A.as_list()); + +const fn tail_offset<T>(list: &List<T>) -> isize { + unsafe { (addr_of!(list.tail) as *const u8).offset_from(list as *const List<T> as *const u8) } +} + +fn main() { + assert_eq!(A_REF.as_slice(), &[5, 6, 7]); + // Check that interpreter and code generation agree about the position of the tail field. + assert_eq!(A_TAIL_OFFSET, tail_offset(A_REF)); +} |