diff options
| -rw-r--r-- | src/librustc_mir/interpret/eval_context.rs | 17 | ||||
| -rw-r--r-- | src/librustc_mir/interpret/place.rs | 13 | ||||
| -rw-r--r-- | src/libstd/time.rs | 2 | ||||
| -rw-r--r-- | src/test/ui/consts/const-eval/issue-55541.rs | 27 |
4 files changed, 54 insertions, 5 deletions
diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs index dbda506d115..ce7269d1e78 100644 --- a/src/librustc_mir/interpret/eval_context.rs +++ b/src/librustc_mir/interpret/eval_context.rs @@ -340,8 +340,21 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tc // the last field). Can't have foreign types here, how would we // adjust alignment and size for them? let field = layout.field(self, layout.fields.count() - 1)?; - let (unsized_size, unsized_align) = self.size_and_align_of(metadata, field)? - .expect("Fields cannot be extern types"); + let (unsized_size, unsized_align) = match self.size_and_align_of(metadata, field)? { + Some(size_and_align) => size_and_align, + None => { + // A field with extern type. If this field is at offset 0, we behave + // like the underlying extern type. + // FIXME: Once we have made decisions for how to handle size and alignment + // of `extern type`, this should be adapted. It is just a temporary hack + // to get some code to work that probably ought to work. + if sized_size == Size::ZERO { + return Ok(None) + } else { + bug!("Fields cannot be extern types, unless they are at offset 0") + } + } + }; // FIXME (#26403, #27023): We should be adding padding // to `sized_size` (to accommodate the `unsized_align` diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs index 201d320dcd8..fa76eeb2fed 100644 --- a/src/librustc_mir/interpret/place.rs +++ b/src/librustc_mir/interpret/place.rs @@ -351,8 +351,17 @@ where // Offset may need adjustment for unsized fields let (meta, offset) = if field_layout.is_unsized() { // re-use parent metadata to determine dynamic field layout - let (_, align) = self.size_and_align_of(base.meta, field_layout)? - .expect("Fields cannot be extern types"); + let align = match self.size_and_align_of(base.meta, field_layout)? { + Some((_, align)) => align, + None if offset == Size::ZERO => + // An extern type at offset 0, we fall back to its static alignment. + // FIXME: Once we have made decisions for how to handle size and alignment + // of `extern type`, this should be adapted. It is just a temporary hack + // to get some code to work that probably ought to work. + field_layout.align, + None => + bug!("Cannot compute offset for extern type field at non-0 offset"), + }; (base.meta, offset.abi_align(align)) } else { // base.meta could be present; we might be accessing a sized field of an unsized diff --git a/src/libstd/time.rs b/src/libstd/time.rs index d124cf53dda..58be1972a81 100644 --- a/src/libstd/time.rs +++ b/src/libstd/time.rs @@ -481,7 +481,7 @@ mod tests { let (a, b) = ($a, $b); if a != b { let (a, b) = if a > b {(a, b)} else {(b, a)}; - assert!(a - Duration::new(0, 100) <= b, + assert!(a - Duration::new(0, 1000) <= b, "{:?} is not almost equal to {:?}", a, b); } }) diff --git a/src/test/ui/consts/const-eval/issue-55541.rs b/src/test/ui/consts/const-eval/issue-55541.rs new file mode 100644 index 00000000000..611fb89341d --- /dev/null +++ b/src/test/ui/consts/const-eval/issue-55541.rs @@ -0,0 +1,27 @@ +// compile-pass + +// Test that we can handle newtypes wrapping extern types + +#![feature(extern_types, const_transmute)] + +use std::marker::PhantomData; + +extern "C" { + pub type ExternType; +} +unsafe impl Sync for ExternType {} +static MAGIC_FFI_STATIC: u8 = 42; + +#[repr(transparent)] +pub struct Wrapper(ExternType); +pub static MAGIC_FFI_REF: &'static Wrapper = unsafe { + std::mem::transmute(&MAGIC_FFI_STATIC) +}; + +#[repr(transparent)] +pub struct Wrapper2(PhantomData<Vec<i32>>, ExternType); +pub static MAGIC_FFI_REF2: &'static Wrapper2 = unsafe { + std::mem::transmute(&MAGIC_FFI_STATIC) +}; + +fn main() {} |