diff options
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/terminator.rs | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs index 0649bb5617c..cbfe25ca8df 100644 --- a/compiler/rustc_const_eval/src/interpret/terminator.rs +++ b/compiler/rustc_const_eval/src/interpret/terminator.rs @@ -294,17 +294,30 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { /// Unwrap types that are guaranteed a null-pointer-optimization fn unfold_npo(&self, layout: TyAndLayout<'tcx>) -> InterpResult<'tcx, TyAndLayout<'tcx>> { - // Check if this is `Option` wrapping some type. - let inner = match layout.ty.kind() { - ty::Adt(def, args) if self.tcx.is_diagnostic_item(sym::Option, def.did()) => { - args[0].as_type().unwrap() - } - _ => { - // Not an `Option`. - return Ok(layout); + // Check if this is `Option` wrapping some type or if this is `Result` wrapping a 1-ZST and + // another type. + let ty::Adt(def, args) = layout.ty.kind() else { + // Not an ADT, so definitely no NPO. + return Ok(layout); + }; + let inner = if self.tcx.is_diagnostic_item(sym::Option, def.did()) { + // The wrapped type is the only arg. + self.layout_of(args[0].as_type().unwrap())? + } else if self.tcx.is_diagnostic_item(sym::Result, def.did()) { + // We want to extract which (if any) of the args is not a 1-ZST. + let lhs = self.layout_of(args[0].as_type().unwrap())?; + let rhs = self.layout_of(args[1].as_type().unwrap())?; + if lhs.is_1zst() { + rhs + } else if rhs.is_1zst() { + lhs + } else { + return Ok(layout); // no NPO } + } else { + return Ok(layout); // no NPO }; - let inner = self.layout_of(inner)?; + // Check if the inner type is one of the NPO-guaranteed ones. // For that we first unpeel transparent *structs* (but not unions). let is_npo = |def: AdtDef<'tcx>| { |