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cpp_typecheck_bases.cpp
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210 lines (164 loc) · 5.15 KB
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/*******************************************************************\
Module: C++ Language Type Checking
Author: Daniel Kroening, [email protected]
\*******************************************************************/
/// \file
/// C++ Language Type Checking
#include "cpp_typecheck.h"
#include <set>
#include "cpp_typecheck_fargs.h"
void cpp_typecheckt::typecheck_compound_bases(struct_typet &type)
{
std::set<irep_idt> bases;
std::set<irep_idt> vbases;
irep_idt default_class_access = type.default_access();
irept::subt &bases_irep=type.add(ID_bases).get_sub();
for(auto &base : bases_irep)
{
const cpp_namet &name = to_cpp_name(base.find(ID_name));
exprt base_symbol_expr=
resolve(
name,
cpp_typecheck_resolvet::wantt::TYPE,
cpp_typecheck_fargst());
if(base_symbol_expr.id()!=ID_type)
{
error().source_location=name.source_location();
error() << "expected type as struct/class base" << eom;
throw 0;
}
// elaborate any class template instances given as bases
elaborate_class_template(base_symbol_expr.type());
if(base_symbol_expr.type().id() != ID_struct_tag)
{
error().source_location=name.source_location();
error() << "expected type symbol as struct/class base" << eom;
throw 0;
}
const symbolt &base_symbol =
lookup(to_struct_tag_type(base_symbol_expr.type()));
if(base_symbol.type.id() != ID_struct)
{
error().source_location=name.source_location();
error() << "expected struct or class as base, but got '"
<< to_string(base_symbol.type) << "'" << eom;
throw 0;
}
if(to_struct_type(base_symbol.type).is_incomplete())
{
error().source_location=name.source_location();
error() << "base type is incomplete" << eom;
throw 0;
}
bool virtual_base = base.get_bool(ID_virtual);
irep_idt class_access = base.get(ID_protection);
if(class_access.empty())
class_access = default_class_access;
base_symbol_expr.id(ID_base);
base_symbol_expr.set(ID_access, class_access);
if(virtual_base)
base_symbol_expr.set(ID_virtual, true);
base.swap(base_symbol_expr);
// Add base scopes as parents to the current scope
cpp_scopes.current_scope().add_secondary_scope(
static_cast<cpp_scopet &>(*cpp_scopes.id_map[base_symbol.name]));
const struct_typet &base_struct_type=
to_struct_type(base_symbol.type);
add_base_components(
base_struct_type,
class_access,
type,
bases,
vbases,
virtual_base);
}
if(!vbases.empty())
{
// add a flag to determine
// if this is the most-derived-object
struct_typet::componentt most_derived(
cpp_scopes.current_scope().prefix + "::" + "@most_derived", bool_typet());
most_derived.set_access(ID_public);
most_derived.set_base_name("@most_derived");
most_derived.set_pretty_name("@most_derived");
most_derived.add_source_location()=type.source_location();
put_compound_into_scope(most_derived);
to_struct_type(type).components().push_back(most_derived);
}
}
void cpp_typecheckt::add_base_components(
const struct_typet &from,
const irep_idt &access,
struct_typet &to,
std::set<irep_idt> &bases,
std::set<irep_idt> &vbases,
bool is_virtual)
{
const irep_idt &from_name = from.get(ID_name);
if(is_virtual && vbases.find(from_name)!=vbases.end())
return;
if(bases.find(from_name)!=bases.end())
{
error().source_location=to.source_location();
error() << "non-virtual base class " << from_name
<< " inherited multiple times" << eom;
throw 0;
}
bases.insert(from_name);
if(is_virtual)
vbases.insert(from_name);
// look at the the parents of the base type
for(const auto &b : from.bases())
{
irep_idt sub_access = b.get(ID_access);
if(access==ID_private)
sub_access=ID_private;
else if(access==ID_protected && sub_access!=ID_private)
sub_access=ID_protected;
const symbolt &symb = lookup(b.type());
const bool is_virtual_base = b.get_bool(ID_virtual);
// recursive call
add_base_components(
to_struct_type(symb.type),
sub_access,
to,
bases,
vbases,
is_virtual_base);
}
// add the components
struct_typet::componentst &dest_c=to.components();
for(const auto &c : from.components())
{
if(c.get_bool(ID_from_base))
continue;
// copy the component
dest_c.push_back(c);
// now twiddle the copy
struct_typet::componentt &component=dest_c.back();
component.set(ID_from_base, true);
irep_idt comp_access=component.get_access();
if(access==ID_public)
{
if(comp_access==ID_private)
component.set_access(ID_noaccess);
}
else if(access == ID_protected)
{
if(comp_access==ID_private)
component.set_access(ID_noaccess);
else
component.set_access(ID_private);
}
else if(access == ID_private)
{
if(comp_access == ID_noaccess || comp_access == ID_private)
component.set_access(ID_noaccess);
else
component.set_access(ID_private);
}
else
UNREACHABLE;
// put into scope
}
}