find_library: Validate and sort globbed shared library files

We need to pick the library with the highest version, which is what
the OpenBSD linker also does.

https://github.com/mesonbuild/meson/issues/3570#issuecomment-403638752

mesonbuild/compilers/c.py

@@ -866,12 +866,29 @@ class CCompiler(Compiler):
         return patterns
 
     @staticmethod
-    def _get_trials_from_pattern(pattern, directory, libname):
+    def _sort_shlibs_openbsd(libs):
+        filtered = []
+        for lib in libs:
+            # Validate file as a shared library of type libfoo.so.X.Y
+            ret = lib.rsplit('.so.', maxsplit=1)
+            if len(ret) != 2:
+                continue
+            try:
+                float(ret[1])
+            except ValueError:
+                continue
+            filtered.append(lib)
+        float_cmp = lambda x: float(x.rsplit('.so.', maxsplit=1)[1])
+        return sorted(filtered, key=float_cmp, reverse=True)
+
+    @classmethod
+    def _get_trials_from_pattern(cls, pattern, directory, libname):
         f = os.path.join(directory, pattern.format(libname))
+        # Globbing for OpenBSD
         if '*' in pattern:
             # NOTE: globbing matches directories and broken symlinks
             # so we have to do an isfile test on it later
-            return glob.glob(f)
+            return cls._sort_shlibs_openbsd(glob.glob(f))
         return [f]
 
     @staticmethod

run_unittests.py

@@ -522,12 +522,28 @@ class InternalTests(unittest.TestCase):
         self.assertEqual(p, shr)
         p = cc.get_library_naming(env, 'static')
         self.assertEqual(p, stc)
-        p = cc.get_library_naming(env, 'default')
-        self.assertEqual(p, shr + stc)
-        p = cc.get_library_naming(env, 'shared-static')
-        self.assertEqual(p, shr + stc)
         p = cc.get_library_naming(env, 'static-shared')
         self.assertEqual(p, stc + shr)
+        p = cc.get_library_naming(env, 'shared-static')
+        self.assertEqual(p, shr + stc)
+        p = cc.get_library_naming(env, 'default')
+        self.assertEqual(p, shr + stc)
+        # Test find library by mocking up openbsd
+        if platform != 'openbsd':
+            return
+        with tempfile.TemporaryDirectory() as tmpdir:
+            with open(os.path.join(tmpdir, 'libfoo.so.6.0'), 'w') as f:
+                f.write('')
+            with open(os.path.join(tmpdir, 'libfoo.so.5.0'), 'w') as f:
+                f.write('')
+            with open(os.path.join(tmpdir, 'libfoo.so.54.0'), 'w') as f:
+                f.write('')
+            with open(os.path.join(tmpdir, 'libfoo.so.66a.0b'), 'w') as f:
+                f.write('')
+            with open(os.path.join(tmpdir, 'libfoo.so.70.0.so.1'), 'w') as f:
+                f.write('')
+            found = cc.find_library_real('foo', env, [tmpdir], '', 'default')
+            self.assertEqual(os.path.basename(found[0]), 'libfoo.so.54.0')
 
     def test_find_library_patterns(self):
         '''