fix optional-presence comparison

compiler/lower/lower.odin

@@ -561,6 +561,25 @@ lower_compound_expr :: proc(state: ^State, expr_id: hir.Expr_Id) -> ir.Instructi
 			diagnostic=source.INVALID_DIAGNOSTIC,
 		})
 	case .Eq, .Ne, .Lt, .Le, .Gt, .Ge:
+		left_expr := state.hir_module.exprs[expr.left]
+		right_expr := state.hir_module.exprs[expr.right]
+		if left_expr.kind == .None || right_expr.kind == .None {
+			optional_expr := expr.right if left_expr.kind == .None else expr.left
+			optional := lower_nested_expr(state, optional_expr)
+			present := append_instruction(state, ir.Instruction{
+				op=.Optional_Is_Some, span=expr.span, type=types.BOOL,
+				target=ir.INVALID_REF, a=optional, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+			if expr.kind == .Ne {
+				return present
+			}
+			return append_instruction(state, ir.Instruction{
+				op=.Not, span=expr.span, type=types.BOOL,
+				target=ir.INVALID_REF, a=present, b=ir.INVALID_INSTRUCTION,
+				diagnostic=source.INVALID_DIAGNOSTIC,
+			})
+		}
 		left := lower_nested_expr(state, expr.left)
 		right := lower_nested_expr(state, expr.right)
 		predicate := ir.Compare_Predicate.Eq