Remove condition for dimension size

Author: hankluo6

src/lpython/semantics/python_ast_to_asr.cpp

@@ -3907,15 +3907,12 @@ class CommonVisitor : public AST::BaseVisitor<Struct> {
                         ASR::ttype_t *int_type = ASRUtils::TYPE(ASR::make_Integer_t(
                                                         al, loc, 4));
                         ASR::expr_t *neg_idx = ASRUtils::expr_value(index);
-                        ASR::expr_t *dim_size;
-                        if (ASRUtils::extract_physical_type(type) != ASR::array_physical_typeType::DescriptorArray)
-                            dim_size = ASR::down_cast<ASR::Array_t>(type)->m_dims[idx].m_length;
-                        else {
-                            ASR::expr_t *idx_expr = ASRUtils::EXPR(ASR::make_IntegerConstant_t(al, loc, idx + 1, int_type));
-                            dim_size = ASRUtils::EXPR(ASRUtils::make_ArraySize_t_util(al, loc, value, idx_expr, int_type, nullptr, false));
-                        }
+                        // null if the dimension is not known at compile time
+                        ASR::expr_t *dim_size = ASR::down_cast<ASR::Array_t>(type)->m_dims[idx].m_length;
+                        ASR::expr_t *idx_expr = ASRUtils::EXPR(ASR::make_IntegerConstant_t(al, loc, idx + 1, int_type));
+                        ASR::expr_t *size_expr = ASRUtils::EXPR(ASRUtils::make_ArraySize_t_util(al, loc, value, idx_expr, int_type, dim_size, false));
                         index = ASRUtils::EXPR(ASR::make_IntegerBinOp_t(al, loc, 
-                            dim_size, ASR::binopType::Add, neg_idx, int_type, nullptr));
+                            size_expr, ASR::binopType::Add, neg_idx, int_type, nullptr));
                     }
                 }
             } else {