Update compiler on Linux s390x
richardlau opened this issue · comments
@miladfarca has found that there is a nasty gcc bug on s390x with std::optional has_value() (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106355) during review of https://chromium-review.googlesource.com/c/v8/v8/+/5246687 (where V8 is proposing to drop their custom v8::base::Optional for std::optional).
While the upstream gcc bug has supposedly been fixed in gcc 10.5.0, that isn't available via dnf on RHEL 8 as gcc-toolset-10 was "retired" in November 2022 (FWIW gcc-toolset-11 is also considered "retired"), which probably means it is unlikely to get updates (we'll check): https://access.redhat.com/support/policy/updates/rhel-app-streams-life-cycle
What we know so far:
Tested the bug (using the example in bugzilla) on ubi8:
- gcc-toolset-10 with
cc 10.3.1: broken- gcc-toolset-11 with
cc 11.2.1: broken- gcc-toolset-12 with
cc 12.2.1: ok
A quick scan of the Node.js codebase shows we are already using std::optional outside of V8, although I don't know if we're hitting the bug with those usages.
So we're probably going to have to move to at least gcc-toolset-12 for Linux on s390x, and the only question is when and whether we make the switch for existing release lines to be on the safe side. Switching to gcc-toolset-12 should be safe from a runtime compatibility perspective as the code will still be linked against the glibc and libstdc++ versions in base RHEL 8.
FWIW I'm always up for upgrading compilers anywhere 😄
@richardlau is the V8 code with the bug already in existing release lines or if not, likely to be backported ?
@richardlau is the V8 code with the bug already in existing release lines or if not, likely to be backported ?
Current V8 in Node.js uses V8's custom optional. I don't know if the change will end up in the version of V8 we'll end up using in Node.js 22.
Ok so the question is if we need to have a new gcc for Node.js 22 or Node.js 23, right?
Thinking about it, we do often pull in a version of v8 after 22 is cut, so it may not be easy to know that until close to the LTS promotion.
It may be best to assume it will be needed for 22 so that we don't need to update compilers after 22 is cut.