permit all kinds of 0-offsets on ZSTs

RalfJung · RalfJung · commit c1a6df941e04 · 2017-06-22T14:26:17.000-07:00
diff --git a/src/eval_context.rs b/src/eval_context.rs
@@ -906,7 +906,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
             let ptr = ptr.signed_offset(offset, self.memory.layout)?;
             // Do not do bounds-checking for integers or ZST; they can never alias a normal pointer anyway.
             if let PrimVal::Ptr(ptr) = ptr {
-                if !(ptr.points_to_zst() && pointee_size == 0) {
+                if !(ptr.points_to_zst() && (offset == 0 || pointee_size == 0)) {
                     self.memory.check_bounds(ptr, false)?;
                 }
             } else if ptr.is_null()? {

Original file line number	Diff line number	Diff line change
`@@ -906,7 +906,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {`
`906`	`906`	`let ptr = ptr.signed_offset(offset, self.memory.layout)?;`
`907`	`907`	`// Do not do bounds-checking for integers or ZST; they can never alias a normal pointer anyway.`
`908`	`908`	`if let PrimVal::Ptr(ptr) = ptr {`
`909`		`- if !(ptr.points_to_zst() && pointee_size == 0) {`
	`909`	`+ if !(ptr.points_to_zst() && (offset == 0 \|\| pointee_size == 0)) {`
`910`	`910`	`self.memory.check_bounds(ptr, false)?;`
`911`	`911`	`}`
`912`	`912`	`} else if ptr.is_null()? {`