If code is clearly too big for the compile-target device, the AVR-GCC linker errors "region text full" . But not if the result is just some bytes too big. For example for ATmega8 with 0x2000 bytes Flash, there is no error if code is resulting HEX code is going to 0x200A. Those last bytes are usually string contants from what I see.
PonyProg then downloads the .hex also without error. And then currupt strings - or crash ...
How to get a correct error message?
Robert