[Pkg-rust-maintainers] Bug#1040477: librust-syn-1-dev fails to coinstall

[Helmut Grohne]

Package: librust-syn-1-dev
Version: 1.0.109-2
Severity: serious
Justification: fails to (co)install
Control: affects -1 + src:rust-fd-find
User: debian-cross at lists.debian.org
Usertags: ftcbfs
X-Debbugs-Cc: deity at lists.debian.org

librust-syn-1-dev has (among other things) the following metadata:

Provides: librust-syn-1.0.109-dev
Breaks: librust-syn-1.0.109-dev
Multi-Arch: same

It is not clear to me what this is supposed to mean. Can you shed some
light on what this is supposed to achieve?

In any case, apt and dpkg disagree about what this shall mean. apt
thinks that self-breaks are to be ignored and asks dpkg to configure
both of these packages, but dpkg doesn't like that:

| dpkg: dependency problems prevent configuration of librust-syn-1-dev:amd64:
|  librust-syn-1-dev:arm64 (1.0.109-2) breaks librust-syn-1.0.109-dev and is unpacked but not configured.
|   librust-syn-1-dev:amd64 (1.0.109-2) provides librust-syn-1.0.109-dev.
| 
| dpkg: error processing package librust-syn-1-dev:amd64 (--configure):
|  dependency problems - leaving unconfigured

You can reproduce the installation failure using:

mmdebstrap unstable /dev/null --architectures=amd64,arm64 --variant=apt --include=librust-syn-1-dev:amd64,librust-syn-1-dev:arm64

If apt and dose were refusing this situation this were a normal bug at
best. But since dpkg fails badly and leaves the system in an
inconsistent state, I am raising this to rc-severity. Even if we deem
this to be an apt bug or dpkg bug in the end, librust-syn-1-dev must
still be changed since we cannot depend on fixed versions of package
managers being used to install packages.

Helmut