zlib depends on gcc_linux-64 v10* about zlib-feedstock

[isuruf]

I don't know where you got this zlib package, but it's certainly not from conda-forge. Please give the details asked in the issue template and make sure you are using conda-forge.

[ekomarova]

This is the package from conda-forge: https://anaconda.org/conda-forge/zlib/1.2.13/download/linux-64/zlib-1.2.13-h166bdaf_4.tar.bz2
And its rendered recipe shows that exactly gcc v10* id needed:
requires:
- gcc_linux-64 10.*

[ekomarova]

@isuruf Please reopen this issue

[isuruf]

You are omitting information from your comments.
Looking at the lines surrounding it, we only require gcc_linux-64 10.* in test. Why do you care about a dependency in test?

test:
  commands:
    - test -f ${PREFIX}/lib/libz.a
    - test -f ${PREFIX}/lib/libz${SHLIB_EXT}
    - test -f ${PREFIX}/include/zlib.h
  files:
    - test_compile_flags.bat
    - test_compile_flags.c
  requires:
    - gcc_linux-64 10.*

[ekomarova]

My situation is that I have in the one environment zlib and zstd, which have different restrictions for gcc, which causes conflicts when installing test dependencies, such as the compiler.
For zstd this is:
requires:
- cmake
- gcc_linux-64 11.*
- pkg-config
And this means that potentially any user who wants to install these packages in the one environment and test them will not be able to install the test dependencies without encountering conflicts

[isuruf]

Can you please give a MWE that exhibits the bug?

[ekomarova]

This may be a somewhat specific situation, but it can occur to those who use zlib and zstd in their products and then run a full test cycle. And before starting testing, a list of test dependencies is generated, which are taken from the packages. And since zlib and zstd have different constraints for the gcc_linux-64, we end up with two conflicting conditions:
gcc_linux-64 =10.*
gcc_linux-64 =11.*
which leads to confiicts.
To reproduce this, just have file dependencies.txt with the above constraints and try to run command:
conda install --yes --freeze-installed --file dependencies.txt -c conda-forge --override-channels

I assume that conda-forge does not test all the packages together in one environment, because it is not necessary, and therefore this problem will not arise, because not all users need to run tests of some environment which contains packages with different test dependencies, but for those who do, this problem may arise.

[isuruf]

And before starting testing, a list of test dependencies is generated, which are taken from the packages. And since zlib and zstd have different constraints for the gcc_linux-64

This is a misuse of the test dependencies. The test dependencies are meant to be used for testing one package in isolation. We cannot make them work with the test dependencies of other packages. You are on your own when you are using the test dependencies for something that is not supposed to be used for. Sorry.

[ekomarova]

Okay, thank you for your reply.