> On 29 Sep 2026, at 17.43, Jason Merrill <[email protected]> wrote:
>
> On 9/28/26 4:17 AM, Jonas Hansen via Sourceware Forge wrote:
>> From: Jonas Hansen <[email protected]>
>> The call to braced_lists_to_strings in store_init_value does not look
>> through TARGET_EXPR. A constexpr aggregate initialized through one can
>> therefore retain a character array CONSTRUCTOR after constant evaluation.
>> The middle end then treats an element of that array as a single-character
>> string, causing a false -Wformat-truncation warning for a bounded snprintf
>> call that reads only the remaining array elements.
>> Move the existing conversion after constant folding, next to
>> replace_placeholders, so it sees the folded initializer while remaining
>> before split_nonconstant_init. Add diagnostic and runtime regressions
>> covering bounded reads, overreads, truncation, constexpr copy and mutation,
>> templates, embedded nuls, and implicit zero initialization.
>> Tested on x86_64-pc-linux-gnu with related C++ format, initialization,
>> constexpr, narrowing, template, string and #embed tests: 14,435 expected
>> passes and no unexpected results across two test selections. C++ self-tests
>> and the runtime regression, including LTO, also passed. A full bootstrap
>> and complete testsuite run have not been performed.
>> gcc/cp/ChangeLog:
>> PR tree-optimization/127416
>> * typeck2.cc (store_init_value): Move braced_lists_to_strings after
>> constant folding.
>> gcc/testsuite/ChangeLog:
>> PR tree-optimization/127416
>> * g++.dg/warn/Wformat-truncation-nonstring.C: New test.
>> * g++.dg/torture/constexpr-array-string.C: New test.
> The patch looks good, but do you intend to submit this under an FSF copyright
> assignment or the DCO? I don't see either currently.
>
> https://gcc.gnu.org/contribute.html#legal
>
> Jason
>
I’m contributing this patch under DCO 1.1 and certify its terms.
Signed-off-by: Jonas Hansen <[email protected]>
Forge shows PR #232 as merged, although the change appears absent from current
upstream trunk. Could you confirm its status and whether this emailed sign-off
is sufficient, or whether you’d prefer an updated submission?
