forward declaring classes used in template functions that do not allow incomplete types #175
Description
Originally reported on Google Code with ID 175
clang/llvm/iwyu trunk (3.7)
iwyu forward declares classes used in template functions that do not allow incomplete
types (e.g., std::pair<_T1,_T2>). This is similar to the problem of forward declaring
classes used in catch().
If I have a class defined in a namespace in
Example below of a header file:
#include <string>
#include "variant.hpp" //declares ESM::Variant
namespace ESM
{
class ESMReader;
class ESMWriter;
struct Locals
{
std::vector<std::pair<std::string, Variant> > mVariables;
void load (ESMReader &esm);
void save (ESMWriter &esm) const;
};
}
iwyu says:
components/esm/locals.hpp should add these lines:
#include <utility> // for pair
namespace ESM { class Variant; }
//end of file
components/esm/locals.hpp should remove these lines:
- #include "variant.hpp" // lines 7-7
The full include-list for components/esm/locals.hpp:
#include <string> // for string
#include <utility> // for pair
#include <vector> // for vector
namespace ESM { class ESMReader; } // lines 11-11
namespace ESM { class ESMWriter; } // lines 12-12
namespace ESM { class Variant; }
end file
However, replacing #include "variant.hpp" with namespace ESM { class Variant; } causes
the error:
bits/stl_pair.h:102:11: error: field has incomplete type 'ESM::Variant'
since std::pair can't take incomplete types.
thank you! (btw, I'm not a c++ guy, CS, or would even call myself a programmer, so
please excuse any mistakes in my reports)
Reported by showard314 on 2015-02-07 17:41:53