Herbert Valerio Riedel
Hi Malcolm,
On 2017-11-18 at 11:09:28 +0000, Malcolm Wallace wrote:
[...]
But surely the timing for a full build from scratch is not the most important thing to compare? In my work environment, full builds are extremely rare; the common case is an incremental build after pulling changes from upstream. Is this something you can measure?
If Hadrian is more exact about the dependency tracking, I'd expect something close to a full rebuild when I `git pull` from GHC HEAD, since the Git commit and the snapshot versioning we infer from that, pervasively transcends most most artifacts of GHC, and in general you should boot & configure everytime you `git pull` unless you're sure it won't matter.
To be honest, I'm hoping that we can make this less necessary in the future. Relatively few changes really require a re-`configure`. In my experience most changes that current demand reconfigure are in .in files. In these cases I often just hack the changes in to the generated files myself. In principle there is no reason why Hadrian couldn't do this as well. I opened #416 to track this some time ago. Cheers, - Ben