Bug#1080323: gnome-snapshot: FTBFS on armel, armhf: LLVM runs out of memory

[Simon McVittie]

Source: gnome-snapshot
Version: 47~beta-1
Severity: serious
Tags: experimental ftbfs
Justification: fails to build from source (but built successfully in the past)
User: debian-arm at lists.debian.org
Usertags: armel armhf
X-Debbugs-CC: debian-arm at lists.debian.org, debian-rust at lists.debian.org

The new version of gnome-snapshot in experimental FTBFS on armel and
armhf with this error message:

>    Compiling snapshot v46.0.0 (/<<PKGBUILDDIR>>)
>      Running [a long rustc command]
> rustc-LLVM ERROR: out of memory
> Allocation failed
> error: could not compile `snapshot` (bin "snapshot")

Presumably this is actually running out of address space available to a
single process, which is 2G on 32-bit if I understand correctly.
This probably affects the other 32-bit architectures equally, but some
build-dependencies are missing on i386 and on all 32-bit -ports
architectures, so we cannot yet confirm or deny that.

Is there anything that can be done in the rustc/cargo options to reduce
memory consumption, like perhaps reducing optimizations or debug symbol
coverage?

Whether this can be fixed will affect the decision being made in #1080153
about cheese vs. gnome-snapshot in the src:meta-gnome3 metapackages. If
gnome-snapshot becomes unavailable on armel/armhf/i386, we'll have to do
architecture-specific removals; but then if we decide that gnome-snapshot
is preferred on 64-bit architectures, we will need to either continue to
have cheese (and therefore clutter-1.0, which is unmaintained upstream)
available for at least the 32-bit architectures, or omit webcam
integration from the metapackages on 32-bit (or not provide the metapackages
at all on 32-bit, but that will require coordination with the release team).

    smcv