Actually they're produced because they're not using it properly...
EDIT:
In case you're interested in the exact cause, it is the use of
__declspec.
This is MSVC syntax, not valid for MinGW. Who said using compiler-specific stuff was bad practice?
Anyway, as a workaround for the ignorant, MinGW has a
__declspec macro, which looks like
#define __declspec(x) __attribute__ (( x ))
Maybe it looks slightly different, I did not learn it by heart, but it should be about like this
But... they do not only use compiler-specifics in wxWidgets, they also use them in places where they should not, hence the warning "Attributes are only honoured..."
And you all were bashing me for using attributes and underscores...