diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs index 4eb95f20d9354..91263932ccd98 100644 --- a/src/librustc_mir/interpret/machine.rs +++ b/src/librustc_mir/interpret/machine.rs @@ -54,6 +54,11 @@ pub trait AllocMap { k: K, vacant: impl FnOnce() -> Result ) -> Result<&mut V, E>; + + /// Read-only lookup. + fn get(&self, k: K) -> Option<&V> { + self.get_or(k, || Err(())).ok() + } } /// Methods of this trait signifies a point where CTFE evaluation would fail diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs index c3eec677a4850..56a0e14535bfc 100644 --- a/src/librustc_mir/interpret/memory.rs +++ b/src/librustc_mir/interpret/memory.rs @@ -492,13 +492,18 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> { id: AllocId, liveness: AllocCheck, ) -> InterpResult<'static, (Size, Align)> { - if let Ok(alloc) = self.get(id) { + // # Regular allocations + // Don't use `self.get` here as that will + // a) cause cycles in case `id` refers to a static + // b) duplicate a static's allocation in miri + if let Some((_, alloc)) = self.alloc_map.get(id) { return Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)); } - // can't do this in the match argument, we may get cycle errors since the lock would get - // dropped after the match. + + // # Statics and function pointers + // Can't do this in the match argument, we may get cycle errors since the lock would + // be held throughout the match. let alloc = self.tcx.alloc_map.lock().get(id); - // Could also be a fn ptr or extern static match alloc { Some(GlobalAlloc::Function(..)) => { if let AllocCheck::Dereferencable = liveness { @@ -507,28 +512,26 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> { } else { Ok((Size::ZERO, Align::from_bytes(1).unwrap())) } - } - // `self.get` would also work, but can cause cycles if a static refers to itself + }, Some(GlobalAlloc::Static(did)) => { - // The only way `get` couldn't have worked here is if this is an extern static - assert!(self.tcx.is_foreign_item(did)); - // Use size and align of the type + // Use size and align of the type. let ty = self.tcx.type_of(did); let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap(); Ok((layout.size, layout.align.abi)) - } - _ => { - if let Ok(alloc) = self.get(id) { - Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)) - } - else if let AllocCheck::MaybeDead = liveness { - // Deallocated pointers are allowed, we should be able to find - // them in the map. - Ok(*self.dead_alloc_map.get(&id) - .expect("deallocated pointers should all be recorded in `dead_alloc_map`")) - } else { - err!(DanglingPointerDeref) - } + }, + Some(GlobalAlloc::Memory(alloc)) => + // Need to duplicate the logic here, because the global allocations have + // different associated types than the interpreter-local ones. + Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)), + // The rest must be dead. + None => if let AllocCheck::MaybeDead = liveness { + // Deallocated pointers are allowed, we should be able to find + // them in the map. + Ok(*self.dead_alloc_map.get(&id) + .expect("deallocated pointers should all be recorded in \ + `dead_alloc_map`")) + } else { + err!(DanglingPointerDeref) }, } } diff --git a/src/test/ui/consts/static-cycle-error.rs b/src/test/ui/consts/static-cycle-error.rs new file mode 100644 index 0000000000000..8e69d3eda6d2e --- /dev/null +++ b/src/test/ui/consts/static-cycle-error.rs @@ -0,0 +1,11 @@ +// compile-pass + +struct Foo { + foo: Option<&'static Foo> +} + +static FOO: Foo = Foo { + foo: Some(&FOO), +}; + +fn main() {}