akonadi-search fails to cross build from source, because it builds a
Rust-based component for the build architecture. It's a CMake package in
principle and uses corrosion (a CMake recipe for integrating a Rust
crate into a CMake project) to have part of its source be implemented in
Rust. And here comes the catch. Corrosion cannot detect the Rust
architecture from other CMake variable and needs to be told via
Rust_CARGO_TARGET. Nothing sets this and hence akonadi-search fails to
cross build.

Now the attached patch simply sets that variable from debian/rules, but
this is a generic problem that likely affects all (4) reverse
dependencies of corrosion. The question arises whether something else
should be setting this variable anticipating more widespread adoption of
corrosion. Any thoughts?

Helmut

Helmut Grohne:


 From a build system maintainer PoV, I am happy to pass that option to
cmake. However, currently the tooling (debhelper and debputy) only has
infrastructure for `dpkg-architecture` provided flags and this value
seems to come from rustc.

The easiest for me would be if this logic moved to `dpkg-architecture`
but I am unsafe if the `dpkg` maintainers want to maintain these flags
going forward.

Best regards,
Niels

Helmut Grohne:


 From a build system maintainer PoV, I am happy to pass that option to
cmake. However, currently the tooling (debhelper and debputy) only has
infrastructure for `dpkg-architecture` provided flags and this value
seems to come from rustc.

The easiest for me would be if this logic moved to `dpkg-architecture`
but I am unsafe if the `dpkg` maintainers want to maintain these flags
going forward.

Best regards,
Niels