The attached patch relaxes -Wformat-overflow=2 to avoid warning about
individual directives that might (but need not) exceed the 4095 byte
limit, and about the total function output that likewise might (but
need not) exceed the INT_MAX limit.

The bug report actually requests that instead of the standard minimum
of 4095 bytes, GCC consider real libc limits, but trying to figure
out what these real limits might be (they're not documented anywhere,
AFAIK) and hardcoding them into GCC doesn't seem like a good solution.

Instead, the patch only does little more than the bare minimum to
suppress these pedantic warnings, and it only does that for the "may
exceed" cases and not for those where the size of output definitely
exceeds either limit.  Using the formatted functions to write such
large amounts of data seems more likely to be a bug than intentional,
and at level 2 issuing the warning seems appropriate unless the return
value of the function is tested.  When it is, even tough exceeding
these limits is strictly undefined, it seems reasonable to assume that
a quality libc implementation will detect it and return an error (as
required by POSIX).

So with the patch, the only way to get this warning is for calls to
sprintf or to unchecked snprintf.

Martin