Build configuration option to ignore a package

[esad]

I had issues with readline compilation, and I realized that the only configuration options for packages that I could use to skip building readline package were -DSWIPL_PACKAGES=OFF to not build any packages and -DSWIPL_PACKAGE_LIST= which required me to name all other packages and leave out readline. It would be great if we had a way to ignore certain packages, something like -DSWIPL_SKIP_PACKAGE_LIST.

[JanWielemaker]

Makes sense. What was the issue though? It is also good if the build drops the package due to issues with the dependencies. Of course, unless these issues where really specific for your system.

Can you try a PR?

[esad]

The issue was on a very nonstandard system that "fakes" readline by copying libedit headers, so swipl build kept wanting to build readline packages, but it kept hitting

#ifndef RL_STATE_INITIALIZED
int rl_readline_state = 0;

Now, it turns out that readline changed signature to long in newer versions so this produced a compile error. I think it's an edge case because in newer versions there would also usually be RL_STATE_INITIALIZED defined.

So far I have figured that simple rm -rf packages/$package before running cmake worked for all packages I wanted to skip.