Always recompile if there were serious warnings

[cgay]

If you compile a library and see serious warnings, you don't see those warnings again when you recompile it. The only way to see the warnings again (without doing build -clean) is to make a no-op change in the library and recompile it. (Note that even if you know where to look for the .log file, it was probably erased when you recompiled hoping to see the warnings again.)

Some might think this is incompatible with Lisp-style rapid development, where you might want to leave unfinished code lying around. If so it should be a command-line flag.

I don't know exactly how build result caching is done, but I imagine hashes of the sources are stored, or something like that. We could just not save the hashes (if there were serious warnings.

[cgay]

So, either automatically rebuild the library that had serious warnings, or automatically redisplay the warnings upon recompilation even if that library doesn't otherwise need recompilation.

Note that [edit: automatically redisplaying the warnings might mean] that the ~10 warnings in the dylan library will be redisplayed all the time, so it increases the need to fix those warnings. (Or to paper them over.)

[cgay]

On the same general topic, but probably a different bug, I notice that if I add the Executable: keyword to the LID file the library doesn't get recompiled and the new executable isn't generated.

[waywardmonkeys]

That issue with the LID file changes is a separate bug.