Merge pull request #1674 from faze-geek/for_loop

Restrict step size 0 in for loop

Author: certik

src/lpython/semantics/python_ast_to_asr.cpp

@@ -4498,6 +4498,10 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
         int64_t inc_int = 1;
         bool is_value_present = ASRUtils::extract_value(inc_value, inc_int);
         if (is_value_present) {
+            if (inc_int == 0) {
+                throw SemanticError("For loop increment should not be zero.", loc);
+            }
+
             // Loop end depends upon the sign of m_increment.
             // if inc > 0 then: loop_end -=1 else loop_end += 1
             ASR::binopType offset_op;