diff options
| -rw-r--r-- | src/librustc_mir/const_eval/machine.rs | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/src/librustc_mir/const_eval/machine.rs b/src/librustc_mir/const_eval/machine.rs index 3d0c5ffae52..3ddff6ea8ca 100644 --- a/src/librustc_mir/const_eval/machine.rs +++ b/src/librustc_mir/const_eval/machine.rs @@ -360,18 +360,18 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter { } else { // Read access. These are usually allowed, with some exceptions. if memory_extra.can_access_statics { - // This is allowed to read from anything. + // Machine configuration allows us read from anything (e.g., `static` initializer). Ok(()) - } else if allocation.mutability == Mutability::Mut || static_def_id.is_some() { - // This is a potentially dangerous read. - // We *must* error on any access to a mutable global here, as the content of - // this allocation may be different now and at run-time, so if we permit reading - // now we might return the wrong value. - // We conservatively also reject all statics here, but that could be relaxed - // in the future. + } else if static_def_id.is_some() { + // Machine configuration does not allow us to read statics + // (e.g., `const` initializer). Err(ConstEvalErrKind::ConstAccessesStatic.into()) } else { // Immutable global, this read is fine. + // But make sure we never accept a read from something mutable, that would be + // unsound. The reason is that as the content of this allocation may be different + // now and at run-time, so if we permit reading now we might return the wrong value. + assert_eq!(allocation.mutability, Mutability::Not); Ok(()) } } |