[feature] Associate CMake target with specific libs

[uilianries]

Hi!

Some packages requires multiple targets, because they have more than one library or configuration. For instance: https://github.com/conan-io/conan-center-index/pull/486/files#diff-e5f7472687ce110b2ecd373150bb38c0

As you can see, OpenSSL contains 2 targets, OpenSSL::Crypto and OpenSSL::SSL.

We could manage cpp_info to provide such feature:

def cpp_info(self):
    self.cpp_info.names["cmake"].targets["Crypto"].libs = ["crypto"]
    self.cpp_info.names["cmake"].targets["SSL"].libs = ["ssl"]
    if self.options.shared:
        self.cpp_info.names["cmake"].targets["SSL"].defines = ["SSL_SHARED"]

related issue: #6069

• I've read the CONTRIBUTING guide.

[memsharded]

Is this a duplicate of the components feature? #5090

It was tried some time ago, there was a PR from @danimtb, but was put on hold because some risks and not a huge priority.

[danimtb]

It looks very similar to the proposal in #5090 indeed. @gocarlos @uilianries are we missing something here?

[uilianries]

Indeed, #5090 sounds be the saint graal of cpp_info!