I'm trying to add at least *some* type of pass-by-value support for C++ classes when wrapping C++ libraries to D. I figured I could fake a value class by using a D struct with a thunk field which matches the size of the C++ object.
Returning a C++ object by value works in this plain C++ example (using g++ on win32): test.cpp: http://codepad.org/55pttk3I $ g++ -m32 -g test.cpp -o main.exe -lstdc++ $ main.exe If I take the same code but remove main and instead use a D driver app like so: test.cpp: http://codepad.org/ZqieSXrb main.d: http://codepad.org/6E5sbc7e I compile it: $ g++ -m32 -g -c ./test.cpp -o test.obj $ gdc -m32 -g main.d test.obj -o main.exe -lstdc++ $ main.exe and then I get a crash: The instruction at "0x6fc8ea39" referenced memory at "0x006f6f62". The memory could not be "read". GDB tells me: Program received signal SIGSEGV, Segmentation fault. 0x6fc8ea39 in libstdc++-6!_ZNSsC1ERKSs () from C:\MinGW\bin\libstdc++-6.dll If I replace the std::string field with an ordinary 'char*' the crash is gone, so my wild guess is the crash happens in one of std::string's special member functions (ctor/dtor/etc..). C++ sizeof() tells me FileName is 4 bytes long, so I've matched that in the fake D struct. If I increase the 'thunk' field to 9 bytes the crash disappears. I have a hunch stack corruption might be to blame. I can notice some difference in the ASM listings: C++ plain sample: http://pastebin.com/xw3BhwwR D driver sample: http://pastebin.com/TLa8k5A3 The suspicious thing there is the missing LEA instruction in the D listing. If I change the thunk field to 9 bytes the LEA instruction appears again (and this is when the crash disappears). My ASM-foo is really weak though, so I don't know what any of this means. Anyone know what's going on?
