Fix showing `!source` on tags when tags cog is reloaded

Previously the source command checks for the source object's class after
getting it from the SourceType converter. When the tags cog is reloaded,
TagIdentifier is redefined. We were checking whether the old
TagIdentifier class (the `type()` of an instance of the old
TagIdentifier) equals the newly defined TagIdentifier class. This
returns false because the TagIdentifier class is redefined when the tags
cog is reloaded, which caused tags, correctly identified by Source
converter, to be unable to be identified in the source cog.

The fix takes advantage of the fact that the source converter could
correctly identify tags objects even after the tags cog reloads, and use
enum comparisons rather than `isinstance`/`type()` to obtain the source
type of whatever the source converter returns.

Since we're no longer using the source converter as an actual converter,
the function is moved to the source cog instead, and it still works
fine.

2 files changed, 55 insertions, 48 deletions

diff --git a/bot/converters.py b/bot/converters.py
index 34a764567..c04158d4d 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -10,7 +10,7 @@ import discord
 from aiohttp import ClientConnectorError
 from dateutil.relativedelta import relativedelta
 from discord.ext.commands import BadArgument, Context, Converter, IDConverter, MemberConverter, UserConverter
-from discord.utils import escape_markdown, snowflake_time
+from discord.utils import snowflake_time
 from pydis_core.site_api import ResponseCodeError
 from pydis_core.utils import unqualify
 from pydis_core.utils.regex import DISCORD_INVITE
@@ -19,7 +19,6 @@ from bot import exts, instance as bot_instance
 from bot.constants import URLs
 from bot.errors import InvalidInfractionError
 from bot.exts.info.doc import _inventory_parser
-from bot.exts.info.tags import TagIdentifier
 from bot.log import get_logger
 from bot.utils import time
 
@@ -220,39 +219,6 @@ class Snowflake(IDConverter):
         return snowflake
 
 
-class SourceConverter(Converter):
-    """Convert an argument into a help command, tag, command, or cog."""
-
-    @staticmethod
-    async def convert(ctx: Context, argument: str) -> SourceType:
-        """Convert argument into source object."""
-        if argument.lower() == "help":
-            return ctx.bot.help_command
-
-        cog = ctx.bot.get_cog(argument)
-        if cog:
-            return cog
-
-        cmd = ctx.bot.get_command(argument)
-        if cmd:
-            return cmd
-
-        tags_cog = ctx.bot.get_cog("Tags")
-        show_tag = True
-
-        if not tags_cog:
-            show_tag = False
-        else:
-            identifier = TagIdentifier.from_string(argument.lower())
-            if identifier in tags_cog.tags:
-                return identifier
-        escaped_arg = escape_markdown(argument)
-
-        raise BadArgument(
-            f"Unable to convert '{escaped_arg}' to valid command{', tag,' if show_tag else ''} or Cog."
-        )
-
-
 class DurationDelta(Converter):
     """Convert duration strings into dateutil.relativedelta.relativedelta objects."""
 
diff --git a/bot/exts/info/source.py b/bot/exts/info/source.py
index 1c3387e53..9dd5c39bf 100644
--- a/bot/exts/info/source.py
+++ b/bot/exts/info/source.py
@@ -1,15 +1,25 @@
+import enum
 import inspect
 from pathlib import Path
 
 from discord import Embed
 from discord.ext import commands
+from discord.utils import escape_markdown
 
 from bot.bot import Bot
 from bot.constants import URLs
-from bot.converters import SourceConverter
 from bot.exts.info.tags import TagIdentifier
 
-SourceType = commands.HelpCommand | commands.Command | commands.Cog | TagIdentifier | commands.ExtensionNotLoaded
+SourceObject = commands.HelpCommand | commands.Command | commands.Cog | TagIdentifier | commands.ExtensionNotLoaded
+
+class SourceType(enum.StrEnum):
+    """The types of source objects recognized by the source command."""
+
+    help_command = enum.auto()
+    command = enum.auto()
+    cog = enum.auto()
+    tag = enum.auto()
+    extension_not_loaded = enum.auto()
 
 
 class BotSource(commands.Cog):
@@ -23,7 +33,7 @@ class BotSource(commands.Cog):
         self,
         ctx: commands.Context,
         *,
-        source_item: SourceConverter = None,
+        source_item: str | None = None,
     ) -> None:
         """Display information and a GitHub link to the source code of a command, tag, or cog."""
         if not source_item:
@@ -33,20 +43,51 @@ class BotSource(commands.Cog):
             await ctx.send(embed=embed)
             return
 
-        embed = await self.build_embed(source_item)
+        obj, source_type = await self.get_source_object(ctx, source_item)
+        embed = await self.build_embed(obj, source_type)
         await ctx.send(embed=embed)
 
-    def get_source_link(self, source_item: SourceType) -> tuple[str, str, int | None]:
+    @staticmethod
+    async def get_source_object(ctx: commands.Context, argument: str) -> tuple[SourceObject, SourceType]:
+        """Convert argument into the source object and source type."""
+        if argument.lower() == "help":
+            return ctx.bot.help_command, SourceType.help_command
+
+        cog = ctx.bot.get_cog(argument)
+        if cog:
+            return cog, SourceType.cog
+
+        cmd = ctx.bot.get_command(argument)
+        if cmd:
+            return cmd, SourceType.command
+
+        tags_cog = ctx.bot.get_cog("Tags")
+        show_tag = True
+
+        if not tags_cog:
+            show_tag = False
+        else:
+            identifier = TagIdentifier.from_string(argument.lower())
+            if identifier in tags_cog.tags:
+                return identifier, SourceType.tag
+
+        escaped_arg = escape_markdown(argument)
+
+        raise commands.BadArgument(
+            f"Unable to convert '{escaped_arg}' to valid command{', tag,' if show_tag else ''} or Cog."
+        )
+
+    def get_source_link(self, source_item: SourceObject, source_type: SourceType) -> tuple[str, str, int | None]:
         """
         Build GitHub link of source item, return this link, file location and first line number.
 
         Raise BadArgument if `source_item` is a dynamically-created object (e.g. via internal eval).
         """
-        if isinstance(source_item, commands.Command):
+        if source_type == SourceType.command:
             source_item = inspect.unwrap(source_item.callback)
             src = source_item.__code__
             filename = src.co_filename
-        elif isinstance(source_item, TagIdentifier):
+        elif source_type == SourceType.tag:
             tags_cog = self.bot.get_cog("Tags")
             filename = tags_cog.tags[source_item].file_path
         else:
@@ -56,7 +97,7 @@ class BotSource(commands.Cog):
             except TypeError:
                 raise commands.BadArgument("Cannot get source for a dynamically-created object.")
 
-        if not isinstance(source_item, TagIdentifier):
+        if source_type != SourceType.tag:
             try:
                 lines, first_line_no = inspect.getsourcelines(src)
             except OSError:
@@ -77,17 +118,17 @@ class BotSource(commands.Cog):
 
         return url, file_location, first_line_no or None
 
-    async def build_embed(self, source_object: SourceType) -> Embed | None:
+    async def build_embed(self, source_object: SourceObject, source_type: SourceType) -> Embed | None:
         """Build embed based on source object."""
-        url, location, first_line = self.get_source_link(source_object)
+        url, location, first_line = self.get_source_link(source_object, source_type)
 
-        if isinstance(source_object, commands.HelpCommand):
+        if source_type == SourceType.help_command:
             title = "Help Command"
             description = source_object.__doc__.splitlines()[1]
-        elif isinstance(source_object, commands.Command):
+        elif source_type == SourceType.command:
             description = source_object.short_doc
             title = f"Command: {source_object.qualified_name}"
-        elif isinstance(source_object, TagIdentifier):
+        elif source_type == SourceType.tag:
             title = f"Tag: {source_object}"
             description = ""
         else: