Pretty impressive new feature of gcc/g++ available in the latest devkitarm.
Look at that.

MapWindow.cxx:377:23: warning: %i directive output may be truncated writing  between 1 and 2 bytes into a region of size between 0 and 9 [-Wformat-truncation]
snprintf(msg, 32, "@%i,%i : %s [%ix%i]",xpos, ypos, why,
                   ^~~~~~~~~~~~~~~~~~~~~
MapWindow.cxx:689:12: report("editing meta-layer");
                       ~~~~~~~~~~~~~~~~~~~~
MapWindow.cxx:377:23: note: directive argument in the range [8, 16] MapWindow.cxx:377:23: note: directive argument in the range [8, 16]  note: 'snprintf' output between 32 and 42 bytes into a destination of size 32

- gcc detected that I'm calling that snprintf function with a value of 'why' that is actually the "editing meta-layer" string, which is 18 bytes long
- it understood that this and some numbers had to fit within 32-bytes output
- the format characters only take 9 bytes
- xpos and ypos are 16-bit values, needing at most 5 characters to be rendered on-screen
- 18 + 9 + 4 = 31. that's the case where all the numbers take only 1 byte. We have barely enough room to display the message (and its terminating zero character)
- 18 + 9 + 5 + 5 + 2 + 2 = 41. That's the case where we ha...