Add semantic error test for assignment to literal

src/lpython/semantics/python_ast_to_asr.cpp

@@ -1,5 +1,4 @@
 #include <fstream>
-#include <iostream>
 #include <map>
 #include <set>
 #include <memory>
@@ -5654,6 +5653,18 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
             assign_value = ASRUtils::EXPR(tmp);
         }
         for (size_t i=0; i<x.n_targets; i++) {
+            if (AST::is_a<AST::ConstantStr_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantInt_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantBool_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantFloat_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantComplex_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantEllipsis_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantNone_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::ConstantBytes_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::Set_t>(*x.m_targets[i]) ||
+                AST::is_a<AST::Dict_t>(*x.m_targets[i])) {
+                throw SemanticError("SyntaxError: cannot assign to literal", x.m_targets[i]->base.loc);
+            }
             tmp_value = assign_value;
             check_is_assign_to_input_param(x.m_targets[i]);
             if (AST::is_a<AST::Subscript_t>(*x.m_targets[i])) {

tests/errors/reproduce_bug_01.out

@@ -0,0 +1,9 @@
+semantic error: SyntaxError: cannot assign to literal
+ --> tests/errors/reproduce_bug_01.py:2:1
+  |
+2 | 'a' = 1
+  | ^^^ 
+
+
+Note: Please report unclear, confusing or incorrect messages as bugs at
+https://github.com/lfortran/lfortran/issues.

tests/errors/reproduce_bug_01.py

@@ -0,0 +1,2 @@
+# TEST EXPECTS SEMANTIC ERROR
+'a' = 1