On Wed, Aug 9, 2017 at 8:40 AM, Adrian Bunk <b...@debian.org> wrote:
> Source: urweb
> Version: 20170720+dfsg-1
> Severity: serious
>
> […]
>
> https://buildd.debian.org/status/package.php?p=urweb&suite=sid
I’m able to reproduce this on asachi, the arm64 porterbox. However,
vanilla upstream builds fine, so this is indeed a Debian bug.
The primary difference between upstream’s build and Debian’s is that
Debian builds with more aggressive optimization flags by passing a
-cc-opt containing -O2 to MLton. (MLton defaults to compiling with -O1.)
I did an arm64 build with -O1 (i.e., I put
export DEB_CFLAGS_MAINT_APPEND := -O1
in debian/rules), and everything worked fine. This suggests that there’s
a bug in MLton’s C codegen which triggers under -O2 on arm64 and
mips64el. A GCC bug is also possible, but I think that’s less likely.
I’m doing a mips64el build with -O1 right now to see if that fixes the
issue on mipsel64. If it does, I’ll start binary-searching the
individual -O2 optimization flags to see exactly what’s triggering
this.
