Remove handling of typecast-on-lhs

Language front-ends should not generate such code, and even if there is a goto
program having such we do handle it in the back-end (such as goto-symex) anyway.

Author: tautschnig

src/goto-programs/goto_convert.cpp

@@ -706,37 +706,11 @@ void goto_convertt::convert_assign(
     do_cpp_new(lhs, to_side_effect_expr(rhs), dest);
   }
   else if(
-    rhs.id() == ID_side_effect &&
-    (rhs.get(ID_statement) == ID_assign ||
-     rhs.get(ID_statement) == ID_postincrement ||
-     rhs.get(ID_statement) == ID_preincrement ||
-     rhs.get(ID_statement) == ID_statement_expression ||
-     rhs.get(ID_statement) == ID_gcc_conditional_expression))
-  {
-    // handle above side effects
-    clean_expr(rhs, dest, mode);
-
-    if(lhs.id() == ID_typecast)
-    {
-      DATA_INVARIANT(
-        lhs.operands().size() == 1, "Typecast must have one operand");
-
-      // add a typecast to the rhs
-      exprt new_rhs = rhs;
-      rhs.make_typecast(lhs.op0().type());
-
-      // remove typecast from lhs
-      exprt tmp = lhs.op0();
-      lhs.swap(tmp);
-    }
-
-    code_assignt new_assign(code);
-    new_assign.lhs() = lhs;
-    new_assign.rhs() = rhs;
-
-    copy(new_assign, ASSIGN, dest);
-  }
-  else if(rhs.id() == ID_side_effect)
+    rhs.id() == ID_side_effect && rhs.get(ID_statement) != ID_assign &&
+    rhs.get(ID_statement) != ID_postincrement &&
+    rhs.get(ID_statement) != ID_preincrement &&
+    rhs.get(ID_statement) != ID_statement_expression &&
+    rhs.get(ID_statement) != ID_gcc_conditional_expression)
   {
     // preserve side effects that will be handled at later stages,
     // such as allocate, new operators of other languages, e.g. java, etc
@@ -754,16 +728,6 @@ void goto_convertt::convert_assign(
     // do everything else
     clean_expr(rhs, dest, mode);
 
-    if(lhs.id()==ID_typecast)
-    {
-      // add a typecast to the rhs
-      rhs.make_typecast(to_typecast_expr(lhs).op().type());
-
-      // remove typecast from lhs
-      exprt tmp=lhs.op0();
-      lhs.swap(tmp);
-    }
-
     code_assignt new_assign(code);
     new_assign.lhs()=lhs;
     new_assign.rhs()=rhs;