https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101134
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |WONTFIX
Status|UNCONFIRMED |RESOLVED
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
GCC cannot determine every arbitrarily complex invariant in a complex program.
If a precondition must be true true that a flow-dependent warning doesn't know
about then asserting it usually both avoids the warning and improves codegen.
In the test case adding either of the two assertions below has that effect:
res = func(str, src, size);
if (size <= 0)
__builtin_unreachable ();
str->data()[size - 1] = '\0';
...
// If we get here, dest was completely filled (dest == end)
if (dest == destBuf->data ())
__builtin_unreachable ();
*(dest-1) = 0;
return (dest-begin);
In future releases, as optimizations improve GCC may be able to determine more
preconditions and the warning might disappear on its own as well.
