Provide config.log from builders

[Dave-Allured (Dave Allured)]

Add config.log to available builder outputs, in addition to stdio and main.log. This is important for obscure failures from configure.

Was previously requested in mega-ticket: #51995

[ryandesign (Ryan Carsten Schmidt)]

I think the reason why we haven't worked on adding this or other desired features is that we expected to migrate from buildbot 0.8 to a newer version, and we didn't want to spend time implementing a feature for buildbot 0.8 just to have to spend more time porting it to a later version. But then we didn't upgrade.

[Dave-Allured (Dave Allured)]

Yes I understand. This ticket is a bookmark in case someone decides to work on config.log.

So, supporting config.log seems like a relatively simple clone of what is done now for main.log. It is likely that I am oversimplifying. However, if you would like to give me a few quick pointers, I would be willing to take a look at the mpbb code to support this.

[ryandesign (Ryan Carsten Schmidt)]

I've never looked into how this might be done so I can't give many pointers. Changes would probably be needed in both mpbb and the buildbot configuration. Setting up a local instance of the buildbot is a task in and of itself but would be a good thing to do if you plan to make improvements to the buildbot.

Providing the contents of main.log is simple in that every port has one and it's always at a predictable location. config.log files, on the other hand, are an artifact of autotools build systems so not all ports have them and those that do might have them in different places. Some ports have multiple config.log files because they have multiple nested configure scripts; gettext is an example of that. Some use different build systems, like cmake or meson, that have log files of different names but that serve a similar purpose.

[jmroot (Joshua Root)]

For reference, the code that base uses to find all the config.log and equivalents for the purpose of looking for implicit declaration errors: ​https://github.com/macports/macports-base/blob/v2.9.0/src/port1.0/portconfigure.tcl#L1881-L1882