interfaces: move peer `capabilities()` to the `ipeercapabilities` interface

I'm not sure why this was on the `ipeercommands` interface.  It appears to be
because these interfaces started out as `_basewirecommands` to hold wire
commands, back in 558f5b2ee10e.  The capabilities interface wasn't split out
until 98861a2298b5, when it pulled the capability related methods off of the
`ipeerbase` interface.  Perhaps it was an oversight to not look at the commands
interface because, while this is a wire command, both `sshpeer` and `httppeer`
now perform a handshake while instantiating the peer object, and cache a fixed
list of capabilities in that object.  Likewise, `localpeer` is given a fixed set
of capabilities when instantiated.  Back in 558f5b2ee10e, `httppeer` looks like
it issued a wire command when this method was called, but `sshpeer` obtained and
cached the capabilities when instantiated, and this method always returned a
fixed value.

There's a perfectly good interface with other capability related methods, and
having it here makes it easier to implement the base `peer` mixin class.

mercurial/httppeer.py

@@ -437,11 +437,13 class httppeer(wireprotov1peer.wirepeer)
 
     # End of ipeerconnection interface.
 
-    # Begin of ipeercommands interface.
+    # Begin of ipeercapabilities interface.
 
     def capabilities(self):
         return self._caps
 
+    # End of ipeercapabilities interface.
+
     def _finish_inline_clone_bundle(self, stream):
         # HTTP streams must hit the end to process the last empty
         # chunk of Chunked-Encoding so the connection can be reused.
@@ -449,8 +451,6 class httppeer(wireprotov1peer.wirepeer)
         if chunk:
             self._abort(error.ResponseError(_(b"unexpected response:"), chunk))
 
-    # End of ipeercommands interface.
-
     def _callstream(self, cmd, _compressible=False, **args):
         args = pycompat.byteskwargs(args)
 

mercurial/interfaces/repository.py

@@ -205,6 +205,13 class ipeercapabilities(Protocol):
         """
 
     @abc.abstractmethod
+    def capabilities(self):
+        """Obtain capabilities of the peer.
+
+        Returns a set of string capabilities.
+        """
+
+    @abc.abstractmethod
     def requirecap(self, name: bytes, purpose: bytes) -> None:
         """Require a capability to be present.
 
@@ -228,13 +235,6 class ipeercommands(Protocol):
         """
 
     @abc.abstractmethod
-    def capabilities(self):
-        """Obtain capabilities of the peer.
-
-        Returns a set of string capabilities.
-        """
-
-    @abc.abstractmethod
     def get_cached_bundle_inline(self, path):
         """Retrieve a clonebundle across the wire.
 
@@ -470,9 +470,7 class peer(_ipeerconnection, ipeercapabi
         self.path = path
 
     def capable(self, name: bytes) -> bool | bytes:
-        # TODO: this class should maybe subclass ipeercommands too, otherwise it
-        #  is assuming whatever uses this as a mixin also has this interface.
-        caps = self.capabilities()  # pytype: disable=attribute-error
+        caps = self.capabilities()
         if name in caps:
             return True
 

mercurial/localrepo.py

@@ -339,14 +339,18 class localpeer(repository.peer): # (re
 
     # End of _basepeer interface.
 
+    # Begin of ipeercapabilities interface.
+
+    def capabilities(self):
+        return self._caps
+
+    # End of ipeercapabilities interface.
+
     # Begin of _basewirecommands interface.
 
     def branchmap(self):
         return self._repo.branchmap()
 
-    def capabilities(self):
-        return self._caps
-
     def get_cached_bundle_inline(self, path):
         # not needed with local peer
         raise NotImplementedError

mercurial/sshpeer.py

@@ -439,12 +439,12 class sshv1peer(wireprotov1peer.wirepeer
 
     # End of ipeerconnection interface.
 
-    # Begin of ipeercommands interface.
+    # Begin of ipeercapabilities interface.
 
     def capabilities(self):
         return self._caps
 
-    # End of ipeercommands interface.
+    # End of ipeercapabilities interface.
 
     def _readerr(self):
         _forwardoutput(self.ui, self._pipee)