cln-grpc: Allow fields to be mapped to None to ignore them

`listpeers` is a rather deeply nested structure which has a couple of
caveats, namely that we use the same enum multiple times, which causes
naming clashes. So we truncate the state_changes[]. We can later map
them if needed, but it'll get much easier once we have an abstract
model description that isn't JSON schema, which unrolls all types,
causing us to generate those enums multiple times.

contrib/msggen/msggen/grpc.py

@@ -26,9 +26,9 @@ typemap = {
 
 # Manual overrides for some of the auto-generated types for paths
 overrides = {
-    'ListPeers.peers[].channels[].state_changes[].old_state': "ChannelState",
-    'ListPeers.peers[].channels[].state_changes[].new_state': "ChannelState",
-    'ListPeers.peers[].channels[].state_changes[].cause': "ChannelStateChangeCause",
+    # Truncate the tree here, it's a complex structure with identitcal
+    # types
+    'ListPeers.peers[].channels[].state_changes[]': None,
     'ListPeers.peers[].channels[].opener': "ChannelSide",
     'ListPeers.peers[].channels[].closer': "ChannelSide",
     'ListPeers.peers[].channels[].features[]': "string",
@@ -107,6 +107,9 @@ class GrpcGenerator:
         self.write(f"""{prefix}}}\n""", False)
 
     def generate_message(self, message: CompositeField):
+        if overrides.get(message.path, "") is None:
+            return
+
         self.write(f"""
         message {message.typename} {{
         """)
@@ -117,6 +120,9 @@ class GrpcGenerator:
                 self.generate_enum(f, indent=1)
 
         for i, f in enumerate(message.fields):
+            if overrides.get(f.path, "") is None:
+                continue
+
             opt = "optional " if not f.required else ""
             if isinstance(f, ArrayField):
                 typename = typemap.get(f.itemtype.typename, f.itemtype.typename)
@@ -171,6 +177,9 @@ class GrpcConverterGenerator:
     def generate_composite(self, prefix, field: CompositeField):
         """Generates the conversions from JSON-RPC to GRPC.
         """
+        if overrides.get(field.path, "") is None:
+            return
+
         # First pass: generate any sub-fields before we generate the
         # top-level field itself.
         for f in field.fields:
@@ -186,12 +195,18 @@ class GrpcConverterGenerator:
         """)
 
         for f in field.fields:
+            if overrides.get(f.path, "") is None:
+                continue
+
             name = f.normalized()
             if isinstance(f, ArrayField):
                 self.write(f"{name}: c.{name}.iter().map(|s| s.into()).collect(),\n", numindent=3)
 
             elif isinstance(f, EnumField):
-                self.write(f"{name}: c.{name} as i32,\n", numindent=3)
+                if f.required:
+                    self.write(f"{name}: c.{name} as i32,\n", numindent=3)
+                else:
+                    self.write(f"{name}: c.{name}.map(|v| v as i32),\n", numindent=3)
 
             elif isinstance(f, PrimitiveField):
                 typ = f.typename + ("?" if not f.required else "")
@@ -266,6 +281,9 @@ class GrpcUnconverterGenerator(GrpcConverterGenerator):
     def generate_composite(self, prefix, field: CompositeField) -> None:
         # First pass: generate any sub-fields before we generate the
         # top-level field itself.
+        if overrides.get(field.path, "") is None:
+            return
+
         for f in field.fields:
             if isinstance(f, ArrayField):
                 self.generate_array(prefix, f)