On Mon., 30 Sep. 2019, 7:43 pm Petr Viktorin, <encukou@gmail.com> wrote:
On 2019-09-30 00:33, Nick Coghlan wrote:
[...]
> We'll never change the size of the config structs (or any other public
> struct) in a maintenance branch

But we *will* change it in alphas/betas, and then we will ask people to
try their software out with these.
Of course, there are no actual API/ABI guarantees with alphas/betas:
officially, you need to rebuild everything for each new pre-release. But
with the goal being to find bugs rather than provide correct software,
it's OK to take shortcuts (if you can then distinguish the bugs the
shortcuts cause from actual bugs in the code).

Issuing proper version mismatch errors (instead of random cryptic
segfaults) could make for a much nicer experience when testing several
successive alphas/betas.

That's actually the variant I implemented in my PR (release candidates and final releases allow nominally compatible inexact matches, everything else requires an exact version match).

Cheers,
Nick.