Add support for CONAN_INSTALL_BUILD_CONFIGURATIONS

[craigscott-crascit]

Let the user or project override the set of build types we execute the conan install command for. This is most useful for enabling projects to build only one configuration when using a multi-config generator, but it can also be used to install for multiple build types with a single-config generator.

Fixes: #705

[CLAassistant]

All committers have signed the CLA.

[craigscott-crascit]

@jcar87 I've updated the docs, but don't know what you want to do for the tests. If you're happy to take care of that, please go ahead and push commits to my branch as needed.

[memsharded]

This is looking good, many thanks for your contribution @craigscott-crascit

I'd like to have the feedback from @jcar87 too.

[craigscott-crascit]

I fixed the failing test. Would be good to trigger another round of CI jobs to confirm that was the only problem.

[craigscott-crascit]

I also added a couple of tests for the new CONAN_INSTALL_BUILD_CONFIGURATIONS variable. Not sure if that's following the style you're after, but hopefully it's in the ballpark.

[jcar87]

Thanks @craigscott-crascit for the PR and for taking the time to implement the tests - our test suite in cmake-conan is not very ergonomic, so we appreciate it!

Need to rebase this on top of develop2 after #698 was merged, happy to do so ourselves and take over the rest if you're okay with that? (although I suspect it will pass the tests just fine)

[craigscott-crascit]

Need to rebase this on top of develop2 after #698 was merged, happy to do so ourselves and take over the rest if you're okay with that?

Yes, please take it over and push changes as you wish. Thanks.

[jcar87]

The tests are failing for a very interesting set of circumstances. (The main being that in that Test class, the build directory is reused and doing an actual build highlights an actual issue with the Conan CMakeDeps generator)

Need to discuss with @memsharded tomorrow, when we have a single config CMake generator, runing conan install on multiple configurations will cause files to overwrite each other in the generators folder, and if the installed configuration differs from the "self" configuration, we need to use a the &:build_pattern=${CMAKE_BUILD_TYPE} to tell Conan what the actual build time for the top-level self project is.

For a multi config generator, I'm not sure 100% it would be an issue, but double checking.

for what it's worth, all of these problems should go away with the CMakeConfigDeps generators, which intends to output files that much closer to what CMake itself would (with the added bonus of being able consume config files inside the packages too)

[craigscott-crascit]

If we're saying only a single value can be given in CONAN_INSTALL_BUILD_CONFIGURATIONS when using a single-config generator, then this needs to be reworded.

[jcar87]

Agreed, working on this!

[craigscott-crascit]

...all of these problems should go away with the CMakeConfigDeps generators, which intends to output files that much closer to what CMake itself would (with the added bonus of being able consume config files inside the packages too)

I cannot express how happy the end of that comment makes me. :)