C front-end: struct components cannot be procedures

Cleanup of unnecessary branches: Any such component would be a function
pointer, not an actual code-typed element.

Author: tautschnig

src/ansi-c/c_typecheck_initializer.cpp

@@ -271,7 +271,10 @@ void c_typecheck_baset::designator_enter(
 
     for(const auto &c : struct_type.components())
     {
-      if(c.type().id() != ID_code && !c.get_is_padding())
+      DATA_INVARIANT(
+        c.type().id() != ID_code, "struct member must not be of code type");
+
+      if(!c.get_is_padding())
       {
         entry.subtype = c.type();
         break;
@@ -456,9 +459,12 @@ exprt::operandst::const_iterator c_typecheck_baset::do_designated_initializer(
 
       DATA_INVARIANT(index<components.size(),
                      "member designator is bounded by components size");
-      DATA_INVARIANT(components[index].type().id()!=ID_code &&
-                     !components[index].get_is_padding(),
-                     "member designator points at data member");
+      DATA_INVARIANT(
+        components[index].type().id() != ID_code,
+        "struct member must not be of code type");
+      DATA_INVARIANT(
+        !components[index].get_is_padding(),
+        "member designator points at non-padding member");
 
       dest=&(dest->operands()[index]);
     }
@@ -736,8 +742,7 @@ void c_typecheck_baset::increment_designator(designatort &designator)
             (components[entry.index].get_is_padding() ||
              (components[entry.index].get_anonymous() &&
               components[entry.index].type().id() != ID_struct_tag &&
-              components[entry.index].type().id() != ID_union_tag) ||
-             components[entry.index].type().id() == ID_code))
+              components[entry.index].type().id() != ID_union_tag)))
       {
         entry.index++;
       }

src/ansi-c/expr2c.cpp

@@ -2073,8 +2073,8 @@ std::string expr2ct::convert_struct(
 
   for(const auto &component : struct_type.components())
   {
-    if(o_it->type().id()==ID_code)
-      continue;
+    DATA_INVARIANT(
+      o_it->type().id() != ID_code, "struct member must not be of code type");
 
     if(component.get_is_padding() && !include_padding_components)
     {