[libcxx] Support Python 3.8 in the test suite

[broadwaylamb]

Summary

platform.linux_distribution() has been deprecated in Python 3.5 and removed in Python 3.8.

[broadwaylamb]

Could anyone verify this patch, please?

[jroelofs]

Either way, LGTM.

libcxx/utils/libcxx/test/target_info.py

216

Did you consider using this instead? One downside is that it brings in one more dependency.

import distro
return distro.linux_distribution(full_distribution_name=False)

[broadwaylamb]

libcxx/utils/libcxx/test/target_info.py

216

I did, but as far as I understand, the community doesn't really want any dependencies.

I've also been answered on the mailing lists that bringing it it wouldn't really worth it.

[mgorny]

@broadwaylamb, I've requested backporting this to 10.x: https://bugs.llvm.org/show_bug.cgi?id=44905. However, i wasn't able to find to find you on Bugzilla and CC you. Could you confirm whether it's fine to backport, please?

[broadwaylamb]

In D72501#1875887, @mgorny wrote:

@broadwaylamb, I've requested backporting this to 10.x: https://bugs.llvm.org/show_bug.cgi?id=44905. However, i wasn't able to find to find you on Bugzilla and CC you. Could you confirm whether it's fine to backport, please?

I don't see any reason for not backporting it, so I guess it's fine by me.

libcxx/utils/libcxx/test/target_info.py

 
 class LinuxLocalTI(DefaultTargetInfo):
     def __init__(self, full_config):
         super(LinuxLocalTI, self).__init__(full_config)
 
     def platform(self):
         return 'linux'
 
+    def _distribution(self):
+        try:
+            # linux_distribution is not available since Python 3.8
+            # However, this function is only used to detect SLES 11,
+            # which is quite an old distribution that doesn't have
+            # Python 3.8.
+            return platform.linux_distribution()
+        except AttributeError:
+            return '', '', ''
+
     def platform_name(self):
-        name, _, _ = platform.linux_distribution()
+        name, _, _ = self._distribution()
         # Some distros have spaces, e.g. 'SUSE Linux Enterprise Server'
         # lit features can't have spaces
         name = name.lower().strip().replace(' ', '-')
         return name # Permitted to be None
 
     def platform_ver(self):
-        _, ver, _ = platform.linux_distribution()
+        _, ver, _ = self._distribution()
         ver = ver.lower().strip().replace(' ', '-')
         return ver # Permitted to be None.
 
     def add_locale_features(self, features):
         add_common_locales(features, self.full_config.lit_config)
         # Some linux distributions have different locale data than others.
         # Insert the distributions name and name-version into the available
         # features to allow tests to XFAIL on them.