https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80924
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The full output is the following (please include the full diagnostic in bug
reports, not just the notes):
a.c:4:34: warning: ‘snprintf’ output may be truncated before the last format
character [-Wformat-truncation=]
snprintf(buf,5,"-%d",idx);
^~~~~
a.c:4:9: note: ‘__builtin_snprintf’ output between 3 and 6 bytes into a
destination of size 5
snprintf(buf,5,"-%d",idx);
^~~~~~~~~~~~~~~~~~~~~~~~~
Compiling the test case with -fdump-tree-printf-return-value shows the
following:
a.c:4: __builtin_snprintf: objsize = 5, fmtstr = "-%d"
Directive 1 at offset 0: "-", length = 1
Result: 1, 1, 1, 1 (1, 1, 1, 1)
Directive 2 at offset 1: "%d"
Result: 1, 4, 4, 4 (2, 5, 5, 5)
Directive 3 at offset 3: "", length = 1
(The Result: consists of the minimum, likely, maximum, and unlikely maximum
number of bytes output by each directive, with running totals for the four
counters in parentheses.)
The VR_RANGE reported by get_range_info() to the warning pass is [0, 1000].
(gdb) p min
$4 = {<wide_int_storage> = {val = {0, 1000, 140737488345088}, len = 1,
precision = 32}, static is_sign_extended = true}
(gdb) p max
$5 = {<wide_int_storage> = {val = {1000, 140737221856280, -1}, len = 1,
precision = 32}, static is_sign_extended = true}
I suspect the root cause is the same as in bug 78969 and this is a dupe of the
latter. (Please reopen this bug if you think otherwise.)
*** This bug has been marked as a duplicate of bug 78969 ***
