Fixed scoping issues of for loops in global scope (#2672)

* Fixed scoping issues of for loops in global scope

* Covered subscripts

* Considered edge case of nested list

* Added white-spaces

* Added integration test

* Removed c backend from test loop_7

* Update src/lpython/semantics/python_ast_to_asr.cpp

Co-authored-by: Shaikh Ubaid <shaikhubaid769@gmail.com>

* Split new test from loop_07 to loop_11 and others

* Added print statements before assert

* Removed explicit cast to str

---------

Co-authored-by: Shaikh Ubaid <shaikhubaid769@gmail.com>

Author: tanay-man

integration_tests/CMakeLists.txt

@@ -518,6 +518,7 @@ RUN(NAME loop_07             LABELS cpython llvm llvm_jit c)
 RUN(NAME loop_08             LABELS cpython llvm llvm_jit c)
 RUN(NAME loop_09             LABELS cpython llvm llvm_jit)
 RUN(NAME loop_10             LABELS cpython llvm llvm_jit)
+RUN(NAME loop_11             LABELS cpython llvm llvm_jit)
 RUN(NAME if_01               LABELS cpython llvm llvm_jit c wasm wasm_x86 wasm_x64)
 RUN(NAME if_02               LABELS cpython llvm llvm_jit c wasm wasm_x86 wasm_x64)
 RUN(NAME if_03    FAIL       LABELS cpython llvm llvm_jit c NOFAST)

integration_tests/loop_11.py

@@ -0,0 +1,42 @@
+from lpython import i32
+
+#checking for loops in the global scope 
+sum: i32 = 0
+i: i32
+for i in [1, 2, 3, 4]:
+    print(i)
+    sum += i
+print("sum = ",sum)
+assert sum == 10
+
+alphabets: str = ""
+c: str
+for c in "abcde":
+    print(c)
+    alphabets += c
+print("alphabets = ",alphabets)
+assert alphabets == "abcde"
+
+alphabets = ""
+s : str = "abcde"
+for c in s[1:4]:
+    print(c)
+    alphabets += c
+print("alphabets = ",alphabets)
+assert alphabets == "bcd"
+
+sum = 0
+num_list : list[i32] = [1, 2, 3, 4]
+for i in num_list[1:3]:
+    print(i)
+    sum += i
+print("sum = ",sum)
+assert sum == 5
+
+sum = 0
+nested_list : list[list[i32]] = [[1, 2, 3, 4]]
+for i in nested_list[0]:
+    print(i)
+    sum += i
+print("sum = ",sum)
+assert sum == 10

src/lpython/semantics/python_ast_to_asr.cpp

@@ -5516,9 +5516,7 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
                 loop_src_var_name = AST::down_cast<AST::Name_t>(sbt->m_value)->m_id;
                 visit_Subscript(*sbt);
                 ASR::expr_t *target = ASRUtils::EXPR(tmp);
-                ASR::symbol_t *loop_src_var_symbol = current_scope->resolve_symbol(loop_src_var_name);
-                ASR::ttype_t *loop_src_var_ttype = ASRUtils::symbol_type(loop_src_var_symbol);
-
+                ASR::ttype_t *loop_src_var_ttype = ASRUtils::expr_type(target);
                 // Create a temporary variable that will contain the evaluated value of Subscript
                 std::string tmp_assign_name = current_scope->get_unique_name("__tmp_assign_for_loop", false);
                 SetChar variable_dependencies_vec;
@@ -5536,7 +5534,11 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
                 ASR::asr_t* assign = ASR::make_Assignment_t(al, x.base.base.loc,
                                 ASRUtils::EXPR(ASR::make_Var_t(al, x.base.base.loc, tmp_assign_variable_sym)),
                                 target, nullptr);
-                current_body->push_back(al, ASRUtils::STMT(assign));
+                if (current_body != nullptr) {
+                    current_body->push_back(al, ASRUtils::STMT(assign));
+                } else {
+                    global_init.push_back(al, assign);
+                }
                 loop_end = for_iterable_helper(tmp_assign_name, x.base.base.loc, explicit_iter_name);
                 for_iter_type = loop_end;
                 LCOMPILERS_ASSERT(loop_end);
@@ -5568,7 +5570,11 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
             ASR::asr_t* assign = ASR::make_Assignment_t(al, x.base.base.loc,
                             ASRUtils::EXPR(ASR::make_Var_t(al, x.base.base.loc, tmp_assign_variable_sym)),
                             target, nullptr);
-            current_body->push_back(al, ASRUtils::STMT(assign));
+            if (current_body != nullptr) {
+                current_body->push_back(al, ASRUtils::STMT(assign));
+            } else {
+                global_init.push_back(al, assign);
+            }
             loop_end = for_iterable_helper(tmp_assign_name, x.base.base.loc, explicit_iter_name);
             for_iter_type = loop_end;
             LCOMPILERS_ASSERT(loop_end);