Diesel 1.4.x makes it impossible to properly cross-compile when using
PostgreSQL and thus having a dependency on libpq. On compile and I
believe when using the diesel_migrations crate, there is a dependency on
both the host and target libpq. Unfortunately, only one can be installed
at a time, because of conflicts. See also:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=995768
Until now the cross-compile solution is based on docker buildx, which
uses qemu to emulate the different targets. This works, but is very,
very slow.
Diesel 2.0.0-rc.0 no longer depends on both the host and target libpq on
compile and makes it possible to implement proper cross-compiling (using
the rust --target flag in combination with the cross-compile
toolchains).
This includes:
* Changing the modulation parameters to its own type.
* Changing the timing parameters to its own type.
* Change the gateway_id to string. As the json encoding for bytes fields
is base64, this was confusing some users.
* Change the uplink / downlink id to uint32 from uuid. A string
representation of the UUID field (for the same reason as the gateway
id) would consome quite some additional bytes. An uint32 provides
sufficient uniqueness for the purpose of uplink / downlink.
