get_software_libdir: return dir if it's only 1 with libs

There are situations e.g. with recent Gentoo where all 64-bit libraries
are under `lib64`, but `lib` is seperate and used for other files and
directories (e.g. `lib/python`), and for 32-bit libraries.

`get_software_libdir` would fail for such. To avoid this:

if `only_one` is `True` (default), *and* no specific file (`fs`) is
specified (also default), *and* `lib` and `lib64` both exist and are
separate, and only one of them has libraries (shared or static),
it returns that one directory.

easybuild/tools/modules.py

@@ -37,6 +37,7 @@
 * Jens Timmerman (Ghent University)
 * David Brown (Pacific Northwest National Laboratory)
 """
+import glob
 import os
 import re
 import shlex
@@ -52,6 +53,7 @@
 from easybuild.tools.module_naming_scheme.mns import DEVEL_MODULE_SUFFIX
 from easybuild.tools.py2vs3 import subprocess_popen_text
 from easybuild.tools.run import run_cmd
+from easybuild.tools.systemtools import get_shared_lib_ext
 from easybuild.tools.utilities import get_subclasses, nub
 
 # software root/version environment variable name prefixes
@@ -1671,6 +1673,7 @@ def get_software_libdir(name, only_one=True, fs=None):
 
     Returns the library subdirectory, relative to software root.
     It fails if multiple library subdirs are found, unless only_one is False which yields a list of all library subdirs.
+    If only_one is True and fs is None, select the one subdirectory with shared or static libraries, if possible.
 
     :param name: name of the software package
     :param only_one: indicates whether only one lib path is expected to be found
@@ -1703,6 +1706,13 @@ def get_software_libdir(name, only_one=True, fs=None):
             if len(res) == 1:
                 res = res[0]
             else:
+                if fs is None:
+                    # check if only one (exactly) has libraries
+                    # this is needed for software with library archives in lib64 but other files/directories in lib
+                    lib_glob = ["*.%s" % ext for ext in ["a", get_shared_lib_ext()]]
+                    haslibs = [any(glob.glob(os.path.join(root, subdir, f)) for f in lib_glob) for subdir in res]
+                    if haslibs[0] != haslibs[1]:
+                        return res[int(not haslibs[0])]
                 raise EasyBuildError("Multiple library subdirectories found for %s in %s: %s",
                                      name, root, ', '.join(res))
         return res

test/framework/modules.py

@@ -674,10 +674,15 @@ def test_get_software_root_version_libdir(self):
             os.environ.pop('EBROOT%s' % env_var_name)
             os.environ.pop('EBVERSION%s' % env_var_name)
 
-        # check expected result of get_software_libdir with multiple lib subdirs
+        # if only 'lib' has a library archive, use it
         root = os.path.join(tmpdir, name)
         mkdir(os.path.join(root, 'lib64'))
         os.environ['EBROOT%s' % env_var_name] = root
+        write_file(os.path.join(root, 'lib', 'foo.a'), 'foo')
+        self.assertEqual(get_software_libdir(name), 'lib')
+
+        # check expected result of get_software_libdir with multiple lib subdirs
+        remove_file(os.path.join(root, 'lib', 'foo.a'))
         self.assertErrorRegex(EasyBuildError, "Multiple library subdirectories found.*", get_software_libdir, name)
         self.assertEqual(get_software_libdir(name, only_one=False), ['lib', 'lib64'])