Fixes Python RPC using Pyodide patch.

Author: hoodmane

build/python_metadata.bzl

@@ -67,8 +67,8 @@ BUNDLE_VERSION_INFO = make_bundle_version_info([
         "pyodide_version": "0.26.0a2",
         "pyodide_date": "2024-03-01",
         "packages": "20240829.4",
-        "backport": 28,
-        "integrity": "sha256-a2F/YpfjuGsVIsx5Z/WSbAaWSHL9vO13puPxX+wKwNI=",
+        "backport": "29",
+        "integrity": "sha256-sVWQzDU+mUsVOp481/oCUuDAWEbKKuc4gxToLVezg6g=",
         "feature_flags": [],
         "emscripten_version": "3.1.52",
         "python_version": "3.12.1",
@@ -79,8 +79,8 @@ BUNDLE_VERSION_INFO = make_bundle_version_info([
         "pyodide_version": "0.27.1",
         "pyodide_date": "2025-01-16",
         "packages": "20250324.1",
-        "backport": 16,
-        "integrity": "sha256-znvAe5OAidJcQyeWeMFClJ5LPgP0QPztxZW/sogb1wI=",
+        "backport": "17",
+        "integrity": "sha256-jV3zgLs1uevw2s9woVGdcRTjkqTWEOg5ToMAWS1mo8w=",
         "feature_flags": ["pythonWorkers20250116"],
         "emscripten_version": "3.1.58",
         "python_version": "3.12.7",

src/pyodide/helpers.bzl

@@ -107,6 +107,10 @@ def _python_bundle(version, *, pyodide_asm_wasm = None, pyodide_asm_js = None, p
             console.error("Failed to read ", libName, e);
         }
     }
+
+    function patchedApplyFunc(func, this_, args) {
+        return Function.prototype.apply.apply(func, [this_, args]);
+    }
     """
 
     REPLACEMENTS = [
@@ -166,6 +170,11 @@ def _python_bundle(version, *, pyodide_asm_wasm = None, pyodide_asm_js = None, p
             "getMemory(",
             "Module.getMemoryPatched(Module, libName, ",
         ],
+        # to fix RPC, applies https://github.com/pyodide/pyodide/commit/8da1f38f7
+        [
+            "nullToUndefined(func.apply(",
+            "nullToUndefined(patchedApplyFunc(func, ",
+        ],
     ]
 
     expand_template(

src/workerd/io/compatibility-date.capnp

@@ -431,7 +431,7 @@ struct CompatibilityFlags @0x8f8c1b68151b6cef {
   pythonWorkers @43 :Bool
       $compatEnableFlag("python_workers")
       $pythonSnapshotRelease(pyodide = "0.26.0a2", pyodideRevision = "2024-03-01",
-          packages = "20240829.4", backport = 28,
+          packages = "20240829.4", backport = 29,
           baselineSnapshotHash = "d13ce2f4a0ade2e09047b469874dacf4d071ed3558fec4c26f8d0b99d95f77b5")
       $impliedByAfterDate(name = "pythonWorkersDevPyodide", date = "2000-01-01");
   # Enables Python Workers. Access to this flag is not restricted, instead bundles containing
@@ -680,7 +680,7 @@ struct CompatibilityFlags @0x8f8c1b68151b6cef {
       $compatEnableFlag("python_workers_20250116")
       $experimental
       $pythonSnapshotRelease(pyodide = "0.27.1", pyodideRevision = "2025-01-16",
-          packages = "20250324.1", backport = 16,
+          packages = "20250324.1", backport = 17,
           baselineSnapshotHash = "TODO");
 
   requestCfOverridesCacheRules @72 :Bool

src/workerd/server/tests/python/durable-object/worker.py

@@ -17,6 +17,9 @@ async def on_fetch(self, req, env, ctx):
     async def no_args_method(self):
         return "value from python"
 
+    async def args_method(self, arg):
+        return "value from python " + arg
+
 
 async def test(ctrl, env, ctx):
     id = env.ns.idFromName("A")
@@ -30,7 +33,8 @@ async def test(ctrl, env, ctx):
     second_resp_data = await second_resp.text()
     assert second_resp_data == "hello from python 2"
 
-    # TODO: Python effectively calls this via `obj.no_args_method.apply(obj, [])` which causes
-    # a DataCloneError to occur. This may be a JS RPC bug that we will need to fix.
-    # custom_resp = await obj.no_args_method()
-    # assert custom_resp == "value from python: 42"
+    no_arg_resp = await obj.no_args_method()
+    assert no_arg_resp == "value from python"
+
+    arg_resp = await obj.args_method("test")
+    assert arg_resp == "value from python test"