Add 32-bit dmd-nightly builds to Travis CI

[WebDrake]

For some reason 32-bit builds are only tested for stable dmd. This seems an oversight: we don't want to find out that the D tools break 32-bit dmd only after a stable release has come out!

This patch therefore adds an extra Travis build with DMD=dmd-nightly and MODEL=32.

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[WebDrake]

Just as a note: the extra packages required suggest that we're testing these 32-bit builds solely on 64-bit systems. Is that intended?

[wilzbach]

we don't want to find out that the D tools break 32-bit dmd only after a stable release has come out!

Then you should add it here:

https://github.com/dlang/ci/blob/master/vars/runPipeline.groovy#L251

No one looks at the CI results of the cron jobs. Well, I do get mails, but I also have a life from time to time.

Just as a note: the extra packages required suggest that we're testing these 32-bit builds solely on 64-bit systems. Is that intended?

There's almost no 32-bit hardware anymore. 32-bit is entirely legacy. My Linux distro even dropped the support half a year ago.

[WebDrake]

Then you should add it here:

I don't quite follow what you want changed ... ?

[WebDrake]

There's almost no 32-bit hardware anymore. 32-bit is entirely legacy. My Linux distro even dropped the support half a year ago.

There are still distros targeting 32-bit architectures, and DMD and its tools are designed to work in 32-bit builds. (I build i386 snap packages, for example.)

Dropping 32-bit support needs to be a conscious policy decision, not something that happens de-facto due to lack of test coverage.

[wilzbach]

I don't quite follow what you want changed ... ?

I don't want anything changed, I'm happy to merge this.
I just told you that adding it here to the CI won't prevent regression (what the motivation of this was) per se, because it's not run on PRs at dmd/druntime/phobos, but dlang/ci is.

(Though OTOH it's very unlikely that the 32-bit codegen at DMD changes without the other testsuites catching it)

[WebDrake]

I just told you that adding it here to the CI won't prevent regression (what the motivation of this was) per se, because it's not run on PRs at dmd/druntime/phobos, but dlang/ci is.

Right. I still don't understand what needs to be changed on the dlang/ci side of things, though ;-)

[wilzbach]

Something like this: dlang/ci#164