https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118557
Bug ID: 118557
Summary: -Wstringop-overflow false positive for span on
array/string_view
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: vermaelen.wouter at gmail dot com
Target Milestone: ---
Hi,
I am aware of bug#88443 which tracks a lot of other reports about
Wstringop-overflow false positives. I checked several (but not all) of the
linked bugs, but I couldn't decide if my report is a duplicate or not. I'll
report it anyway. Feel free to dismiss if it is a duplicate.
I did make some effort to make the test case as small as possible (while still
keeping the origin recognizable). See here: https://godbolt.org/z/s3v8bMEoE
The warning is triggered by the 2 calls to copy() on line 63 and 64. All other
code is just support code.
I'm reasonably sure this code is correct:
* Line 63 copies at most 8 bytes from 'part1' into the first 8 bytes of 'array
a', so the destination is valid and larger or equal to the source size.
* Line 64 copies at most 3 bytes from 'part2' into the last 3 bytes of 'array
a', so again the destination buffer is valid and large enough to hold the
source.
Lines 55-60 and 65 don't fundamentally change the copy behavior, but are
somehow needed to trigger the problem.
The warning message "warning: writing 8 bytes into a region of size 3" seems
wrong to me. We never copy 8 bytes into a region of size 3. Could it be that
the sizes of both copies somehow get mixed up?
