Refactor --list-msgs & --list-msgs-enabled (#4793)

* Refactor ``--list-msgs`` & ``--list-msgs-enabled``
Both options now show which messages can't be emitted with the
current interpreter. This makes function more like their name implies.
This closes #4778

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

ChangeLog

@@ -75,6 +75,11 @@ Release date: TBA
   Closes #3608
   Closes #4346
 
+
+* Refactor of ``--list-msgs`` & ``--list-msgs-enabled``: both options now show whether messages are emittable with the current interpreter.
+
+  Closes #4778
+
 * Fix false negative for ``used-before-assignment`` when the variable is assigned
   in an exception handler, but used outside of the handler.
 

doc/whatsnew/2.10.rst

@@ -62,6 +62,10 @@ Other Changes
   Closes #3608
   Closes #4346
 
+* Refactor of ``--list-msgs`` & ``--list-msgs-enabled``: both options now show whether messages are emittable with the current interpreter.
+
+  Closes #4778
+
 * Fix false negative for ``used-before-assignment`` when the variable is assigned
   in an exception handler, but used outside of the handler.
 

pylint/lint/pylinter.py

@@ -775,22 +775,23 @@ def python3_porting_mode(self):
         self._python3_porting_mode = True
 
     def list_messages_enabled(self):
-        enabled = [
-            f"  {message.symbol} ({message.msgid})"
-            for message in self.msgs_store.messages
-            if self.is_message_enabled(message.msgid)
-        ]
-        disabled = [
-            f"  {message.symbol} ({message.msgid})"
-            for message in self.msgs_store.messages
-            if not self.is_message_enabled(message.msgid)
-        ]
+        emittable, non_emittable = self.msgs_store.find_emittable_messages()
+        enabled = []
+        disabled = []
+        for message in emittable:
+            if self.is_message_enabled(message.msgid):
+                enabled.append(f"  {message.symbol} ({message.msgid})")
+            else:
+                disabled.append(f"  {message.symbol} ({message.msgid})")
         print("Enabled messages:")
-        for msg in sorted(enabled):
+        for msg in enabled:
             print(msg)
         print("\nDisabled messages:")
-        for msg in sorted(disabled):
+        for msg in disabled:
             print(msg)
+        print("\nNon-emittable messages with current interpreter:")
+        for msg in non_emittable:
+            print(f"  {msg.symbol} ({msg.msgid})")
         print("")
 
     # block level option handling #############################################

pylint/lint/run.py

@@ -156,7 +156,8 @@ def __init__(
                         "callback": self.cb_list_messages,
                         "group": "Commands",
                         "level": 1,
-                        "help": "Generate pylint's messages.",
+                        "help": "Display a list of all pylint's messages divided by whether "
+                        "they are emittable with the given interpreter.",
                     },
                 ),
                 (
@@ -167,8 +168,8 @@ def __init__(
                         "callback": self.cb_list_messages_enabled,
                         "group": "Commands",
                         "level": 1,
-                        "help": "Display a list of what messages are enabled "
-                        "and disabled with the given configuration.",
+                        "help": "Display a list of what messages are enabled, "
+                        "disabled and non-emittable with the given configuration.",
                     },
                 ),
                 (

pylint/message/message_definition_store.py

@@ -2,7 +2,7 @@
 # For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
 
 import collections
-from typing import Dict, List, ValuesView
+from typing import Dict, List, Tuple, ValuesView
 
 from pylint.exceptions import UnknownMessageError
 from pylint.message.message_definition import MessageDefinition
@@ -73,9 +73,25 @@ def help_message(self, msgids_or_symbols: List[str]) -> None:
 
     def list_messages(self) -> None:
         """Output full messages list documentation in ReST format."""
+        emittable, non_emittable = self.find_emittable_messages()
+        print("Emittable messages with current interpreter:")
+        for msg in emittable:
+            print(msg.format_help(checkerref=False))
+        print("\nNon-emittable messages with current interpreter:")
+        for msg in non_emittable:
+            print(msg.format_help(checkerref=False))
+        print("")
+
+    def find_emittable_messages(
+        self,
+    ) -> Tuple[List[MessageDefinition], List[MessageDefinition]]:
+        """Finds all emittable and non-emittable messages"""
         messages = sorted(self._messages_definitions.values(), key=lambda m: m.msgid)
+        emittable = []
+        non_emittable = []
         for message in messages:
-            if not message.may_be_emitted():
-                continue
-            print(message.format_help(checkerref=False))
-        print("")
+            if message.may_be_emitted():
+                emittable.append(message)
+            else:
+                non_emittable.append(message)
+        return emittable, non_emittable