Make generator documentation

[danimtb]

Documentation conan-io/conan#3773

[danimtb]

PR conan-io/conan#4003

[solvingj]

One issue of consistency, a few other description updates for clarity.

[danimtb]

Hi @solvingj and thanks a lot for the review.

I have tried to follow the rules defined here: https://docs.conan.io/en/latest/reference/build_helpers/autotools.html#environment-variables

With the information indicated here: https://docs.conan.io/en/latest/reference/conanfile/attributes.html#cpp-info

Following that information the mapping will be:

cpp_info	conanbuildinfo.mak	Makefile
defines	CONAN_DEFINES	CPPFLAGS
includedirs	CONAN_INCLUDE_PATHS	CPPFLAGS
libdirs	CONAN_LIB_PATHS	LDFLAGS
libs	CONAN_LIBS	LIBS
cflags	CONAN_CFLAGS	CFLAGS
cppflags	CONAN_CPPFLAGS	CXXFLAGS

As you see, I think it is better to maintain a similar name for the cpp_info -> generator conversion but use the Make variable naming for the example (generator -> User side). WDYT?

The controversial part here is the cpp_info.cppflags that in my opinion it should have been called cpp_info.cxxflags

[solvingj]

Yes, I mostly agree with it. There are still a few issues to work out though.

Autotools vs Make : LIBS vs LDLIBS
Sadly, and for reasons I have never found, Autotools chose to use a new variable name for this purpose. GNU Make originally used LOADLIBES, then changed to LDLIBS which is what is used today. Autotools came along later and used the shortened variable name LIBS. In short, I think that using LIBS is appropriate for the AutoTools Helper, and using LDLIBS is more likely what people would use in manually managed Makefiles. With that said, i think it's totally fine for the example. It will always be users preference.

CPP vs CXX
Thank you for clarifying. I actually completely forgot about this naming mismatch between Conan and Make/Autotools. I remember seeing it last year, perhaps I blacked it out. I guess I had been working so deeply with Make the past few months, when i came back to work on the generator I just lined things up the way that makes sense and never checked the docs. Sorry about that :(

Since it can never be fixed, I've gone ahead and updated my PR for the unit tests based on your feedback:
conan-io/conan#4018

So, after all that, this looks good :)

[danimtb]

Thanks a lot for the feedback. I will come and update this PR with the variables in the test you proposed on conan-io/conan#4018 😃

[jgsogo]

LGTM