gdbus-codegen: Define only one marshaller per signature reusing across interfaces

Avoid generating more code than needed, so other than continuing using
the generic glib marshallers when possible, define once the custom ones
we need for each file we generate.

The marshallers are then re-used across all the interfaces defined
without duplicating the code size.

gio/gdbus-2.0/codegen/codegen.py

@@ -1462,6 +1462,7 @@ class CodeGenerator:
         self.glib_min_required = glib_min_required
         self.symbol_decoration_define = symbol_decoration_define
         self.outfile = outfile
+        self.marshallers = set()
 
     # ----------------------------------------------------------------------------------------------------
 
@@ -2669,25 +2670,53 @@ class CodeGenerator:
                 "\n" f"  {ret_arg.gvalue_set} (return_value, v_return);\n"
             )
 
+    def generic_marshaller_name(self, args=[], ret=None):
+        name = "_g_dbus_codegen_marshal_"
+        name += f"{ret.gvalue_type.upper() if ret else 'VOID'}__"
+        if args:
+            name += "_".join(f"{a.gvalue_type.upper()}" for a in args)
+        else:
+            name += "VOID"
+        return name
+
+    def generic_marshaller_name_for_type(self, t):
+        assert isinstance(t, (dbustypes.Signal, dbustypes.Method))
+
+        if not t.marshaller_ret_arg:
+            if not t.marshaller_in_args:
+                return "g_cclosure_marshal_VOID__VOID"
+            elif (
+                len(t.marshaller_in_args) == 1
+                and t.marshaller_in_args[0].gclosure_marshaller
+            ):
+                return t.marshaller_in_args[0].gclosure_marshaller
+
+        return self.generic_marshaller_name(t.marshaller_in_args, t.marshaller_ret_arg)
+
+    def generate_generic_marshallers(self, i):
+        for t in i.signals + i.methods:
+            marshaller_name = self.generic_marshaller_name_for_type(t)
+            if marshaller_name.startswith("g_cclosure_"):
+                self.marshallers.add(marshaller_name)
+                continue
+
+            if marshaller_name in self.marshallers:
+                continue
+
+            self.generate_marshaller(
+                marshaller_name, t.marshaller_in_args, t.marshaller_ret_arg
+            )
+            self.marshallers.add(marshaller_name)
+
     def generate_marshaller_for_type(self, i, t):
         assert isinstance(t, (dbustypes.Signal, dbustypes.Method))
 
         kind_uscore = utils.camel_case_to_uscore(t.__class__.__name__.lower())
         func_name = f"{i.name_lower}_{kind_uscore}_marshal_{t.name_lower}"
+        marshaller_name = self.generic_marshaller_name_for_type(t)
+        assert marshaller_name in self.marshallers
 
-        if not t.marshaller_ret_arg:
-            if not t.marshaller_in_args:
-                self.generate_marshaller_wrapper(
-                    func_name, "g_cclosure_marshal_VOID__VOID"
-                )
-                return
-            elif len(t.marshaller_in_args) == 1 and t.args[0].gclosure_marshaller:
-                self.generate_marshaller_wrapper(
-                    func_name, t.args[0].gclosure_marshaller
-                )
-                return
-
-        self.generate_marshaller(func_name, t.marshaller_in_args, t.marshaller_ret_arg)
+        self.generate_marshaller_wrapper(func_name, marshaller_name)
 
     def generate_signal_marshallers(self, i):
         for s in i.signals:
@@ -5419,6 +5448,8 @@ class CodeGenerator:
 
     def generate(self):
         self.generate_body_preamble()
+        for i in self.ifaces:
+            self.generate_generic_marshallers(i)
         for i in self.ifaces:
             self.generate_interface_intro(i)
             self.generate_signals_enum_for_interface(i)