Bug#1085890: loupe: FTBFS on i386: rustc-LLVM ERROR: out of memory; Couldn't compile the test

[Simon McVittie]

Source: loupe
Version: 47.0-1
Severity: serious
Tags: ftbfs
Justification: fails to build from source (but built successfully in the past)
X-Debbugs-Cc: debian-rust at lists.debian.org, bunk at debian.org
Control: block 1085885 by -1
User: debian-qa at lists.debian.org
Usertags: i386

loupe failed to build from source on i386:

https://buildd.debian.org/status/fetch.php?pkg=loupe&arch=i386&ver=47.0-3&stamp=1728056118&raw=0
> running 2 tests
> test src/util/gettext.rs - util::gettext::apply_unicode_escapes (line 46) ... FAILED
> test src/util/gettext.rs - util::gettext::hex_to_char (line 83) ... FAILED
> 
> failures:
> 
> ---- src/util/gettext.rs - util::gettext::apply_unicode_escapes (line 46) stdout ----
> rustc-LLVM ERROR: out of memory
> Allocation failed
> Couldn't compile the test.
> ---- src/util/gettext.rs - util::gettext::hex_to_char (line 83) stdout ----
> rustc-LLVM ERROR: out of memory
> Allocation failed
> Couldn't compile the test.

This seems to be repeatable: the build of 47.0-3 was retried a couple of
times and it fails like this every time. 47.0-1 and -2 had what appears
to be the same issue.

I think the most recent version that built successfully on i386, 46.2-2,
might not have had a test suite at all?

47.0-1 appears to have had the same symptom on armel and armhf, our only
other 32-bit architectures where loupe's build-dependencies are available,
and that was addressed by disabling LTO on those architectures. If
the problem is that the buildd ran out of virtual address space, then
it's going to affect every 32-bit architecture equally, so perhaps this
workaround needs to be extended to all 32-bit architectures? That would
look something like:

-ifneq (,$(filter armel armhf,$(DEB_HOST_ARCH)))
+ifeq ($(DEB_HOST_ARCH_BITS),32)

(Or perhaps the Rust team could arrange for rustc/dh_cargo to disable
memory-hungry optimizations like LTO in all 32-bit builds automatically?)

This is preventing the current version of loupe from migrating to testing
(#1085885).

Thanks,
    smcv