Cleanup GOTO model validation of function calls

Function calls can use dereference expressions or symbol expressions,
but nothing else. There is no need to make this configurable for those
ought to be invariants.

Fixes: #7022

Author: tautschnig

src/goto-programs/validate_goto_model.cpp

@@ -34,9 +34,6 @@ class validate_goto_modelt
   /// until they are linked.
   void entry_point_exists();
 
-  /// Check that no function calls via function pointer are present
-  void function_pointer_calls_removed();
-
   /// Check that for all:
   /// -# functions that are called or
   /// -# functions of which the address is taken
@@ -61,13 +58,7 @@ validate_goto_modelt::validate_goto_modelt(
   if(validation_options.entry_point_exists)
     entry_point_exists();
 
-  if(validation_options.function_pointer_calls_removed)
-  {
-    function_pointer_calls_removed();
-  }
-
-  if(validation_options.check_called_functions)
-    check_called_functions();
+  check_called_functions();
 }
 
 void validate_goto_modelt::entry_point_exists()
@@ -78,23 +69,6 @@ void validate_goto_modelt::entry_point_exists()
     "an entry point must exist");
 }
 
-void validate_goto_modelt::function_pointer_calls_removed()
-{
-  for(const auto &fun : function_map)
-  {
-    for(const auto &instr : fun.second.body.instructions)
-    {
-      if(instr.is_function_call())
-      {
-        DATA_CHECK(
-          vm,
-          instr.call_function().id() == ID_symbol,
-          "no calls via function pointer should be present");
-      }
-    }
-  }
-}
-
 void validate_goto_modelt::check_called_functions()
 {
   auto test_for_function_address =
@@ -123,6 +97,18 @@ void validate_goto_modelt::check_called_functions()
       // check functions that are called
       if(instr.is_function_call())
       {
+        // calls through function pointers are represented by dereference
+        // expressions
+        if(instr.call_function().id() == ID_dereference)
+          continue;
+
+        // the only other permitted expression is a symbol
+        DATA_CHECK(
+          vm,
+          instr.call_function().id() == ID_symbol &&
+            instr.call_function().type().id() == ID_code,
+          "function call expected to be code-typed symbol expression");
+
         const irep_idt &identifier =
           to_symbol_expr(instr.call_function()).get_identifier();
 

src/goto-programs/validate_goto_model.h

@@ -18,18 +18,13 @@ class goto_model_validation_optionst final
   // this check is disabled by default (not all goto programs
   // have an entry point)
   bool entry_point_exists = false;
-
-  bool function_pointer_calls_removed = true;
   bool check_returns_removed = true;
-  bool check_called_functions = true;
 
 private:
   void set_all_flags(bool options_value)
   {
     entry_point_exists = options_value;
-    function_pointer_calls_removed = options_value;
     check_returns_removed = options_value;
-    check_called_functions = options_value;
   }
 
 public:

unit/goto-programs/goto_program_validate.cpp

@@ -132,59 +132,6 @@ SCENARIO("Validation of a goto program", "[core][goto-programs][validate]")
     }
   }
 
-  /// check function_pointer_calls_removed()
-  WHEN("not all function calls via fn pointer have been removed")
-  {
-    THEN("fail!")
-    {
-      // introduce function k that has a function pointer call;
-      symbolt k;
-      k.name = "k";
-      k.mode = ID_C;
-      k.type = code_typet({}, empty_typet{}); // void return, take no params
-
-      code_function_callt function_call{
-        dereference_exprt{fn_ptr.symbol_expr(),
-                          pointer_typet(code_typet{{}, empty_typet{}}, 64)}};
-
-      code_blockt k_body{{function_call}};
-      k.value = k_body;
-
-      goto_model.symbol_table.add(k);
-      goto_convert(goto_model, null_message_handler);
-
-      goto_model_validation_optionst validation_options{
-        goto_model_validation_optionst ::set_optionst::all_false};
-
-      validation_options.function_pointer_calls_removed = true;
-
-      REQUIRE_THROWS_AS(
-        validate_goto_model(
-          goto_model.goto_functions,
-          validation_modet::EXCEPTION,
-          validation_options),
-        incorrect_goto_program_exceptiont);
-    }
-  }
-
-  WHEN("all function calls via fn pointer have been removed")
-  {
-    THEN("pass!")
-    {
-      goto_convert(goto_model, null_message_handler);
-
-      goto_model_validation_optionst validation_options{
-        goto_model_validation_optionst ::set_optionst::all_false};
-
-      validation_options.function_pointer_calls_removed = true;
-
-      REQUIRE_NOTHROW(validate_goto_model(
-        goto_model.goto_functions,
-        validation_modet::EXCEPTION,
-        validation_options));
-    }
-  }
-
   WHEN("all returns have been removed")
   {
     THEN("true!")
@@ -218,8 +165,6 @@ SCENARIO("Validation of a goto program", "[core][goto-programs][validate]")
       goto_model_validation_optionst validation_options{
         goto_model_validation_optionst ::set_optionst::all_false};
 
-      validation_options.check_called_functions = true;
-
       REQUIRE_THROWS_AS(
         validate_goto_model(
           goto_model.goto_functions,
@@ -242,8 +187,6 @@ SCENARIO("Validation of a goto program", "[core][goto-programs][validate]")
       goto_model_validation_optionst validation_options{
         goto_model_validation_optionst ::set_optionst::all_false};
 
-      validation_options.check_called_functions = true;
-
       REQUIRE_THROWS_AS(
         validate_goto_model(
           goto_model.goto_functions,
@@ -264,8 +207,6 @@ SCENARIO("Validation of a goto program", "[core][goto-programs][validate]")
       goto_model_validation_optionst validation_options{
         goto_model_validation_optionst ::set_optionst::all_false};
 
-      validation_options.check_called_functions = true;
-
       REQUIRE_NOTHROW(validate_goto_model(
         goto_model.goto_functions,
         validation_modet::EXCEPTION,