Fix for module-alias on EnvironmentModules and Lmod 6

Deprecate mod_exists_regex_template in favor for better output parsing
Output parsing of module show is now more accurate as errors are handled
and only first non-whitespace line is checked

Usual outputs for non-existant modules: Empty or `(0):ERROR:...`
For existing modules the first line (after comments etc) contains the
full path of the module file with a colon at the end.

easybuild/tools/modules.py

@@ -531,12 +531,12 @@ def module_wrapper_exists(self, mod_name, modulerc_fn='.modulerc', mod_wrapper_r
 
         return wrapped_mod
 
-    def exist(self, mod_names, mod_exists_regex_template=r'^\s*\S*/%s.*:\s*$', skip_avail=False, maybe_partial=True):
+    def exist(self, mod_names, mod_exists_regex_template=None, skip_avail=False, maybe_partial=True):
         """
         Check if modules with specified names exists.
 
         :param mod_names: list of module names
-        :param mod_exists_regex_template: template regular expression to search 'module show' output with
+        :param mod_exists_regex_template: DEPRECATED and unused
         :param skip_avail: skip checking through 'module avail', only check via 'module show'
         :param maybe_partial: indicates if the module name may be a partial module name
         """
@@ -546,22 +546,26 @@ def mod_exists_via_show(mod_name):
 
             :param mod_name: module name
             """
-            txt = self.show(mod_name)
+            stderr = self.show(mod_name)
             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
+            # Parse the output:
+            # - Skip whitespace
+            # - Any error -> Module does not exist
+            # - Check first non-whitespace line for something that looks like an absolute path terminated by a colon
+            mod_exists_regex = r'\s*/.+:\s*'
+            for line in stderr.split('\n'):
+                if OUTPUT_MATCHES['whitespace'].search(line):
+                    continue
+                if OUTPUT_MATCHES['error'].search(line):
                     break
+                if re.match(mod_exists_regex, line):
+                    res = True
+                break
             return res
 
+        if mod_exists_regex_template is not None:
+            self.log.deprecated('mod_exists_regex_template is no longer used', '5.0')
+
         if skip_avail:
             avail_mod_names = []
         elif len(mod_names) == 1:
@@ -1418,19 +1422,6 @@ def module_wrapper_exists(self, mod_name):
 
         return res
 
-    def exist(self, mod_names, skip_avail=False, maybe_partial=True):
-        """
-        Check if modules with specified names exists.
-
-        :param mod_names: list of module names
-        :param skip_avail: skip checking through 'module avail', only check via 'module show'
-        """
-        # module file may be either in Tcl syntax (no file extension) or Lua sytax (.lua extension);
-        # the current configuration for matters little, since the module may have been installed with a different cfg;
-        # Lmod may pick up both Tcl and Lua module files, regardless of the EasyBuild configuration
-        return super(Lmod, self).exist(mod_names, mod_exists_regex_template=r'^\s*\S*/%s.*(\.lua)?:\s*$',
-                                       skip_avail=skip_avail, maybe_partial=maybe_partial)
-
     def get_setenv_value_from_modulefile(self, mod_name, var_name):
         """
         Get value for specific 'setenv' statement from module file for the specified module.

test/framework/modules.py

@@ -279,6 +279,7 @@ def test_exist(self):
 
         java_mod_dir = os.path.join(self.test_prefix, 'Java')
         write_file(os.path.join(java_mod_dir, '1.8.0_181'), '#%Module')
+        write_file(os.path.join(self.test_prefix, 'toy', '42.1337'), '#%Module')
 
         if self.modtool.__class__ == EnvironmentModulesC:
             modulerc_tcl_txt = '\n'.join([
@@ -289,16 +290,21 @@ def test_exist(self):
                 'if {"Java/site_default" eq [module-info version Java/site_default]} {',
                 '    module-version Java/1.8.0_181 site_default',
                 '}',
-                'if {"JavaAlias" eq [module-info version JavaAlias]} {',
-                '    module-alias JavaAlias Java/1.8.0_181',
+                'if {"Java/Alias" eq [module-info version Java/Alias]} {',
+                '    module-alias Java/Alias toy/42.1337',
+                '}',
+                'if {"Java/NonExist" eq [module-info version Java/NonExist]} {',
+                '    module-alias Java/NonExist non_existant/1',
                 '}',
             ])
         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',
-                'module-alias JavaAlias Java/1.8.0_181',
+                'module-alias Java/Alias toy/42.1337',
+                # 'module-alias Java/NonExist non_existant/1',  # (only) LMod has this in module avail, disable for now
+                'module-alias JavaAlias Java/1.8.0_181',  # LMod 7+ only
             ])
 
         write_file(os.path.join(java_mod_dir, '.modulerc'), modulerc_tcl_txt)
@@ -309,13 +315,15 @@ def test_exist(self):
             self.assertTrue('Java/1.8' in avail_mods)
             self.assertTrue('Java/site_default' in avail_mods)
             self.assertTrue('JavaAlias' in avail_mods)
+            self.assertEqual(self.modtool.exist(['JavaAlias']), [True])
 
         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])
-        # And completely different name
-        self.assertEqual(self.modtool.exist(['JavaAlias']), [True])
+        # Check for aliases:
+        # - different version suffix than the base module
+        # - completely different name
+        # - alias to non existant module
+        self.assertEqual(self.modtool.exist(['Java/site_default', 'Java/Alias', 'Java/NonExist']), [True, True, False])
 
         reset_module_caches()