Andrew Johnson

@spinkney is the goal to keep on the log-scale for overflow or underflow? Would you roughly know what values the problem start at?

Passes for me under the `fedora:42` docker image with gcc 15.1: ``` [root@a2b32ce531e0 math]# python ./runTests.py -j4 test/unit/math/mix/fun/multiply_complex_test.cpp ------------------------------------------------------------ make -j4 test/unit/math/mix/fun/multiply_complex_test g++ -std=c++17 -pthread -D_REENTRANT -ffp-contract=off -Wno-sign-compare -Wno-ignored-attributes -Wno-class-memaccess...

Ahh yeah I can also reproduce the failures under the `x64_64` container. I also tried adding `-ffp-contract=off`, which (I think) is the only different compilation flag for aarch64, and there...

I think it's something optimisation-related, the test only fails with `-O3`, it's fine with `-O{0,1,2}`

Narrowed it down a bit further, it only fails when mixing scalar & matrix arguments (not for both scalar or both matrix). It's also definitely caused by the vectorisation of...

The plot continues to thicken. There's some interaction with the use of `eval` in the tests, where if I remove the `eval` call from the [testing functor definitions](https://github.com/stan-dev/math/blob/01fa440c47b8fcb7cde4d358305e755785576571/test/unit/math/test_ad.hpp#L602) then the...

Here's a minimum test-case (essentially just extracting the relevant part of the test framework) to reproduce the error: ```cpp #include #include int main() { using stan::math::serialize_args; using stan::math::serialize_return; using stan::math::to_deserializer;...

Ah yeah the reduced example doesn't trip the auto-vectorisation, you need to add `CPPFLAGS += -O2 -fvect-cost-model=unlimited` to the `make/local` But you can verify the `eval` issue (without makeflag changes)...

I'm not sure if it's related somehow, but I found a different bug when initialising complex vector types: https://gitlab.com/libeigen/eigen/-/issues/2931 I'll see what the Eigen devs say, hopefully there's some central...

> I'm not sure what we should do with this issue re: the upcoming release. Just warn users that there may be issues with the newest gcc? Yeah I think...