gh-145177: Bump emscripten to 5.0.4

Before Emscripten 4.0.19, there was a bug in the dynamic loader that caused any
dynamic library that links libffi to fail to load. _ctypes_test.so unnecessarily
links libffi so it would fail to load and tests that needed it were skipped.

There are two test failures behind that: one involving stack overflows which
we have to skip as usual, and one that assumes that the abi for a function
that takes a single struct with two doubles is the same as the abi for a
function that takes two double arguments. This is not true in webassembly so we
skip the test.

There is another regression in Emscripten 5.0.5 which breaks a couple tests in
test_secrets and test_random, so leave updating past that to a followup.

Author: hoodmane

Lib/test/test_ctypes/test_as_parameter.py

@@ -5,7 +5,7 @@
                     c_short, c_int, c_long, c_longlong,
                     c_byte, c_wchar, c_float, c_double,
                     ArgumentError)
-from test.support import import_helper, skip_if_sanitizer
+from test.support import import_helper, skip_if_sanitizer, skip_emscripten_stack_overflow
 _ctypes_test = import_helper.import_module("_ctypes_test")
 
 
@@ -193,6 +193,7 @@ class S8I(Structure):
                              (9*2, 8*3, 7*4, 6*5, 5*6, 4*7, 3*8, 2*9))
 
     @skip_if_sanitizer('requires deep stack', thread=True)
+    @skip_emscripten_stack_overflow()
     def test_recursive_as_param(self):
         class A:
             pass

Lib/test/test_ctypes/test_structures.py

@@ -302,6 +302,15 @@ class X(Structure):
     def _test_issue18060(self, Vector):
         # Regression tests for gh-62260
 
+        # This test passes a struct of two doubles by value to the atan2(),
+        # whose actual C signature is atan2(double, double), so it only works on
+        # platforms where the abi of a function that takes a struct with two
+        # doubles matches the abi of a function that takes two doubles. The
+        # wasm32 ABI does not satisfy this condition and the test breaks.
+        if support.is_wasm32:
+            self.skipTest(
+                "wasm ABI is incompatible with test expectations")
+
         # The call to atan2() should succeed if the
         # class fields were correctly cloned in the
         # subclasses. Otherwise, it will segfault.

Lib/test/test_platform.py

@@ -534,7 +534,20 @@ def test_ios_ver(self):
 
     def test_libc_ver(self):
         if support.is_emscripten:
-            assert platform.libc_ver() == ("emscripten", "4.0.19")
+            import tomllib
+            from pathlib import Path
+
+            # Get expected emscripten version from emscripten config
+            config_path = (
+                Path(__file__).parents[2] / "Platforms/emscripten/config.toml"
+            )
+            with open(config_path, "rb") as fp:
+                emscripten_version = tomllib.load(fp)["emscripten-version"]
+
+            self.assertEqual(
+                platform.libc_ver(), ("emscripten", emscripten_version)
+            )
+
             return
         # check that libc_ver(executable) doesn't raise an exception
         if os.path.isdir(sys.executable) and \

Platforms/emscripten/config.toml

@@ -1,7 +1,7 @@
 # Any data that can vary between Python versions is to be kept in this file.
 # This allows for blanket copying of the Emscripten build code between supported
 # Python versions.
-emscripten-version = "4.0.19"
+emscripten-version = "5.0.4"
 node-version = "24"
 test-args = [
     "-m", "test",