Added Abseil btree map and flat hash map support

[theunwisewolf]

Added support for abseil containers btree_map and flat_hash_map as requested by @niXman

Please check the CMakeLists.txt, as I added abseil using add_subdirectory(), not sure if that is the right way. Also, you need to do the CI changes yourself.

Also, I have no idea about QT projects, so I did not add the abseil libs to the .pro file.

All tests are passing fine on my local machine.

[theunwisewolf]

I tried fixing the CI process :P

libabsl_str_format_internal in abseil is failing to compile but the tests are running successfully as str_format is not linked to the yas_base_tests binary.

[niXman]

@askamn can you please remove msvc2017 for appveyor tests?

also, any ideas how this can be fixed?

[theunwisewolf]

@niXman By removing MSVC 2017 do you mean remove this line: - Visual Studio 2017?

I have no idea how to fix that.
I have opened an issue on abseil's github. Lets see what happens.
abseil/abseil-cpp#795

[niXman]

By removing MSVC 2017 do you mean remove this line: - Visual Studio 2017?

yes.

I have no idea how to fix that.
I have opened an issue on abseil's github. Lets see what happens.
abseil/abseil-cpp#795

ah, got it. thanks!

[theunwisewolf]

So, I managed to fix the travis build also, by building just the tests instead of "all" execs and libs as abseil also adds a few targets to build and by default cmake will build all the targets. So I just specified the --target yas-base-tests in the build step to make sure only the tests get build and it worked! Now it's no longer compiling abseil libs that are not used by the project.

I am pretty sure if we add back VS2017 and do the same --target thing to appveyor it will also work fine. Because it was also complaining about the same issue.

[theunwisewolf]

They updated the issue, GCC 4.8 isn't supported as written on the bottom https://abseil.io/docs/cpp/platforms/platforms

[niXman]

thank you @askamn !

[niXman]

@askamn

just while trying to build YAS I encountered errors related to the absence of Abseil.
this should not be the case, the user is not obliged to install Abseil if he does not plan to use it.
please fix it as soon as possible.