Also check for module basename in module exist

Allows to find Java/whatver-11 from "module show Java/11"

easybuild/tools/modules.py

@@ -543,9 +543,21 @@ def mod_exists_via_show(mod_name):
 
             :param mod_name: module name
             """
-            mod_exists_regex = mod_exists_regex_template % re.escape(mod_name)
             txt = self.show(mod_name)
-            return bool(re.search(mod_exists_regex, txt, re.M))
+            res = False
+            names_to_check = [mod_name]
+            # The module might be an alias where the target can be arbitrary
+            # As a compromise we check for the base name of the module so we find
+            # "Java/whatever-11" when searching for "Java/11" (--> basename="Java")
+            basename = os.path.dirname(mod_name)
+            if basename:
+                names_to_check.append(basename)
+            for name in names_to_check:
+                mod_exists_regex = mod_exists_regex_template % re.escape(name)
+                if re.search(mod_exists_regex, txt, re.M):
+                    res = True
+                    break
+            return res
 
         if skip_avail:
             avail_mod_names = []
@@ -643,7 +655,7 @@ def show(self, mod_name):
             ans = MODULE_SHOW_CACHE[key]
             self.log.debug("Found cached result for 'module show %s' with key '%s': %s", mod_name, key, ans)
         else:
-            ans = self.run_module('show', mod_name, check_output=False, return_output=True)
+            ans = self.run_module('show', mod_name, check_output=False, return_stderr=True)
             MODULE_SHOW_CACHE[key] = ans
             self.log.debug("Cached result for 'module show %s' with key '%s': %s", mod_name, key, ans)
 
@@ -761,7 +773,9 @@ def run_module(self, *args, **kwargs):
         if kwargs.get('check_output', True):
             self.check_module_output(full_cmd, stdout, stderr)
 
-        if kwargs.get('return_output', False):
+        if kwargs.get('return_stderr', False):
+            return stderr
+        elif kwargs.get('return_output', False):
             return stdout + stderr
         else:
             # the module command was run with an outdated selected environment variables (see LD_ENV_VAR_KEYS list)

test/framework/modules.py

@@ -174,11 +174,15 @@ def test_exist(self):
                 'if {"Java/1.8" eq [module-info version Java/1.8]} {',
                 '    module-version Java/1.8.0_181 1.8',
                 '}',
+                'if {"Java/site_default" eq [module-info version Java/site_default]} {',
+                '    module-version Java/1.8.0_181 site_default',
+                '}',
             ])
         else:
             modulerc_tcl_txt = '\n'.join([
                 '#%Module',
                 'module-version Java/1.8.0_181 1.8',
+                'module-version Java/1.8.0_181 site_default',
             ])
 
         write_file(os.path.join(java_mod_dir, '.modulerc'), modulerc_tcl_txt)
@@ -188,6 +192,8 @@ def test_exist(self):
         if isinstance(self.modtool, Lmod) and StrictVersion(self.modtool.version) >= StrictVersion('7.0'):
             self.assertTrue('Java/1.8' in avail_mods)
         self.assertEqual(self.modtool.exist(['Java/1.8', 'Java/1.8.0_181']), [True, True])
+        # Check for an alias with a different version suffix than the base module
+        self.assertEqual(self.modtool.exist(['Java/site_default']), [True])
         self.assertEqual(self.modtool.module_wrapper_exists('Java/1.8'), 'Java/1.8.0_181')
 
         reset_module_caches()
@@ -199,6 +205,7 @@ def test_exist(self):
         self.assertTrue('Core/Java/1.8.0_181' in self.modtool.available())
         self.assertEqual(self.modtool.exist(['Core/Java/1.8.0_181']), [True])
         self.assertEqual(self.modtool.exist(['Core/Java/1.8']), [True])
+        self.assertEqual(self.modtool.exist(['Core/Java/site_default']), [True])
         self.assertEqual(self.modtool.module_wrapper_exists('Core/Java/1.8'), 'Core/Java/1.8.0_181')
 
         # also check with .modulerc.lua for Lmod 7.8 or newer
@@ -207,12 +214,18 @@ def test_exist(self):
             reset_module_caches()
 
             remove_file(os.path.join(java_mod_dir, '.modulerc'))
-            write_file(os.path.join(java_mod_dir, '.modulerc.lua'), 'module_version("Java/1.8.0_181", "1.8")')
+            write_file(os.path.join(java_mod_dir, '.modulerc.lua'),
+                       '\n'.join([
+                            'module_version("Java/1.8.0_181", "1.8")',
+                            'module_version("Java/1.8.0_181", "site_default")',
+                        ]))
 
             avail_mods = self.modtool.available()
             self.assertTrue('Java/1.8.0_181' in avail_mods)
             self.assertTrue('Java/1.8' in avail_mods)
             self.assertEqual(self.modtool.exist(['Java/1.8', 'Java/1.8.0_181']), [True, True])
+            # Check for an alias with a different version suffix than the base module
+            self.assertEqual(self.modtool.exist(['Java/site_default']), [True])
             self.assertEqual(self.modtool.module_wrapper_exists('Java/1.8'), 'Java/1.8.0_181')
 
             reset_module_caches()
@@ -222,6 +235,7 @@ def test_exist(self):
             self.assertTrue('Core/Java/1.8.0_181' in self.modtool.available())
             self.assertEqual(self.modtool.exist(['Core/Java/1.8.0_181']), [True])
             self.assertEqual(self.modtool.exist(['Core/Java/1.8']), [True])
+            self.assertEqual(self.modtool.exist(['Core/Java/site_default']), [True])
             self.assertEqual(self.modtool.module_wrapper_exists('Core/Java/1.8'), 'Core/Java/1.8.0_181')
 
     def test_load(self):