Fix const step in loop

Author: ubaidsk

src/libasr/pass/pass_utils.cpp

@@ -893,7 +893,8 @@ namespace LCompilers {
                 if( comp == -1 ) {
                     int increment;
                     bool not_constant_inc = false;
-                    if (!ASRUtils::is_integer(*ASRUtils::expr_type(c))) {
+                    if (!ASRUtils::is_integer(*ASRUtils::type_get_past_const(
+                            ASRUtils::expr_type(c)))) {
                         throw LCompilersException("Do loop increment type should be an integer");
                     }
                     if (c->type == ASR::exprType::IntegerConstant) {

src/lpython/semantics/python_ast_to_asr.cpp

@@ -5301,7 +5301,8 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
         head.m_start = loop_start;
         head.m_increment = inc;
 
-        if( !ASR::is_a<ASR::Integer_t>(*ASRUtils::expr_type(inc)) ) {
+        if( !ASR::is_a<ASR::Integer_t>(*ASRUtils::type_get_past_const(
+                ASRUtils::expr_type(inc))) ) {
             throw SemanticError("For loop increment type should be Integer.", loc);
         }
         ASR::expr_t *inc_value = ASRUtils::expr_value(inc);