Create separate documentation page for each message

.gitignore

@@ -9,6 +9,7 @@
 /pylint.egg-info/
 .tox
 *.sw[a-z]
+doc/messages/
 doc/technical_reference/extensions.rst
 doc/technical_reference/features.rst
 pyve

doc/Makefile

@@ -150,6 +150,8 @@ features.rst: $(shell find ../pylint/checkers -type f -regex '.*\.py')
 	rm -f features.rst
 	PYTHONPATH=$(PYTHONPATH) $(PYTHON) ./exts/pylint_features.py
 
+messages: $(PYTHONPATH) $(PYTHON) ./exts/pylint_messages.py
+
 gen-examples:
 	chmod u+w ../examples/pylintrc
 	pylint --rcfile=/dev/null --generate-rcfile > ../examples/pylintrc

doc/conf.py

@@ -36,6 +36,7 @@
 extensions = [
     "pylint_features",
     "pylint_extensions",
+    "pylint_messages",
     "sphinx.ext.autosectionlabel",
     "sphinx.ext.intersphinx",
 ]

doc/exts/pylint_messages.py

@@ -0,0 +1,226 @@
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
+
+"""Script used to generate the messages files."""
+
+import os
+from collections import defaultdict
+from pathlib import Path
+from typing import DefaultDict, Dict, List, NamedTuple, Optional, Tuple
+
+from sphinx.application import Sphinx
+
+from pylint.checkers import initialize as initialize_checkers
+from pylint.constants import MSG_TYPES
+from pylint.extensions import initialize as initialize_extensions
+from pylint.lint import PyLinter
+from pylint.message import MessageDefinition
+from pylint.utils import get_rst_title
+
+PYLINT_BASE_PATH = Path(__file__).resolve().parent.parent.parent
+"""Base path to the project folder"""
+
+PYLINT_MESSAGES_PATH = PYLINT_BASE_PATH / "doc" / "messages"
+"""Path to the messages documentation folder"""
+
+
+MSG_TYPES_DOC = {k: v if v != "info" else "information" for k, v in MSG_TYPES.items()}
+
+
+class MessageData(NamedTuple):
+    checker: str
+    id: str
+    name: str
+    definition: MessageDefinition
+
+
+MessagesDict = Dict[str, List[MessageData]]
+OldMessagesDict = Dict[str, DefaultDict[Tuple[str, str], List[Tuple[str, str]]]]
+"""DefaultDict is indexed by tuples of (old name symbol, old name id) and values are
+tuples of (new name symbol, new name category)
+"""
+
+
+def _register_all_checkers_and_extensions(linter: PyLinter) -> None:
+    """Registers all checkers and extensions found in the default folders."""
+    initialize_checkers(linter)
+    initialize_extensions(linter)
+
+
+def _get_all_messages(
+    linter: PyLinter,
+) -> Tuple[MessagesDict, OldMessagesDict]:
+    """Get all messages registered to a linter and return a dictionary indexed by message
+    type.
+    Also return a dictionary of old message and the new messages they can be mapped to.
+    """
+    messages_dict: MessagesDict = {
+        "fatal": [],
+        "error": [],
+        "warning": [],
+        "convention": [],
+        "refactor": [],
+        "information": [],
+    }
+    old_messages: OldMessagesDict = {
+        "fatal": defaultdict(list),
+        "error": defaultdict(list),
+        "warning": defaultdict(list),
+        "convention": defaultdict(list),
+        "refactor": defaultdict(list),
+        "information": defaultdict(list),
+    }
+    for message in linter.msgs_store.messages:
+        message_data = MessageData(
+            message.checker_name, message.msgid, message.symbol, message
+        )
+        messages_dict[MSG_TYPES_DOC[message.msgid[0]]].append(message_data)
+
+        if message.old_names:
+            for old_name in message.old_names:
+                category = MSG_TYPES_DOC[old_name[0][0]]
+                old_messages[category][(old_name[1], old_name[0])].append(
+                    (message.symbol, MSG_TYPES_DOC[message.msgid[0]])
+                )
+
+    return messages_dict, old_messages
+
+
+def _write_message_page(messages_dict: MessagesDict) -> None:
+    """Create or overwrite the file for each message."""
+    for category, messages in messages_dict.items():
+        category_dir = PYLINT_MESSAGES_PATH / category
+        if not category_dir.exists():
+            category_dir.mkdir(parents=True, exist_ok=True)
+        for message in messages:
+            messages_file = os.path.join(category_dir, f"{message.name}.rst")
+            with open(messages_file, "w", encoding="utf-8") as stream:
+                stream.write(
+                    f""".. _{message.name}:
+
+{get_rst_title(f"{message.name} / {message.id}", "=")}
+**Message emitted:**
+
+{message.definition.msg}
+
+**Description:**
+
+*{message.definition.description}*
+
+Created by ``{message.checker}`` checker
+"""
+                )
+
+
+def _write_messages_list_page(
+    messages_dict: MessagesDict, old_messages_dict: OldMessagesDict
+) -> None:
+    """Create or overwrite the page with the list of all messages."""
+    messages_file = os.path.join(PYLINT_MESSAGES_PATH, "messages_list.rst")
+    with open(messages_file, "w", encoding="utf-8") as stream:
+        # Write header of file
+        stream.write(
+            f""".. _messages-list:
+
+{get_rst_title("Pylint Messages", "=")}
+Pylint can emit the following messages:
+
+"""
+        )
+
+        # Iterate over tuple to keep same order
+        for category in (
+            "fatal",
+            "error",
+            "warning",
+            "convention",
+            "refactor",
+            "information",
+        ):
+            messages = sorted(messages_dict[category], key=lambda item: item.name)
+            old_messages = sorted(old_messages_dict[category], key=lambda item: item[0])
+            messages_string = "".join(
+                f"   {category}/{message.name}.rst\n" for message in messages
+            )
+            old_messages_string = "".join(
+                f"   {category}/{old_message[0]}.rst\n" for old_message in old_messages
+            )
+
+            # Write list per category
+            stream.write(
+                f"""{get_rst_title(category.capitalize(), "-")}
+All messages in the {category} category:
+
+.. toctree::
+   :maxdepth: 2
+   :titlesonly:
+
+{messages_string}
+All renamed messages in the {category} category:
+
+.. toctree::
+   :maxdepth: 1
+   :titlesonly:
+
+{old_messages_string}
+
+"""
+            )
+
+
+def _write_redirect_pages(old_messages: OldMessagesDict) -> None:
+    """Create redirect pages for old-messages."""
+    for category, old_names in old_messages.items():
+        category_dir = PYLINT_MESSAGES_PATH / category
+        if not os.path.exists(category_dir):
+            os.makedirs(category_dir)
+        for old_name, new_names in old_names.items():
+            old_name_file = os.path.join(category_dir, f"{old_name[0]}.rst")
+            with open(old_name_file, "w", encoding="utf-8") as stream:
+                new_names_string = "".join(
+                    f"   ../{new_name[1]}/{new_name[0]}.rst\n" for new_name in new_names
+                )
+                stream.write(
+                    f""".. _{old_name[0]}:
+
+{get_rst_title(" / ".join(old_name), "=")}
+"{old_name[0]} has been renamed. The new message can be found at:
+
+.. toctree::
+   :maxdepth: 2
+   :titlesonly:
+
+{new_names_string}
+"""
+                )
+
+
+# pylint: disable-next=unused-argument
+def build_messages_pages(app: Optional[Sphinx]) -> None:
+    """Overwrite messages files by printing the documentation to a stream.
+    Documentation is written in ReST format.
+    """
+    # Create linter, register all checkers and extensions and get all messages
+    linter = PyLinter()
+    _register_all_checkers_and_extensions(linter)
+    messages, old_messages = _get_all_messages(linter)
+
+    # Write message and category pages
+    _write_message_page(messages)
+    _write_messages_list_page(messages, old_messages)
+
+    # Write redirect pages
+    _write_redirect_pages(old_messages)
+
+
+def setup(app: Sphinx) -> None:
+    """Connects the extension to the Sphinx process"""
+    # Register callback at the builder-inited Sphinx event
+    # See https://www.sphinx-doc.org/en/master/extdev/appapi.html
+    app.connect("builder-inited", build_messages_pages)
+
+
+if __name__ == "__main__":
+    pass
+    # Uncomment to allow running this script by your local python interpreter
+    # build_messages_pages(None)

doc/index.rst

@@ -17,6 +17,7 @@ refactored and can offer you details about the code's complexity.
 
    user_guide/index.rst
    how_tos/index.rst
+   messages/index.rst
    technical_reference/index.rst
    development_guide/index.rst
    additional_commands/index.rst

doc/messages/index.rst

@@ -0,0 +1,11 @@
+.. _messages:
+
+Messages
+===================
+
+.. toctree::
+  :maxdepth: 1
+  :titlesonly:
+
+  messages_introduction
+  messages_list

doc/messages/messages_introduction.rst

@@ -0,0 +1,15 @@
+.. _messages-introduction:
+
+Pylint messages
+================
+
+Pylint can emit various messages. These are categorized according to categories::
+
+    Convention
+    Error
+    Fatal
+    Information
+    Refactor
+    Warning
+
+A list of these messages can be found here: :ref:`messages-list`