gh-128627: Fix iPad detection in wasm-gc by ryanking13 · Pull Request #135388 · python/cpython

ryanking13 · 2025-06-11T13:24:59Z

As of iOS / iPadOS 18.3.1, enabling wasm-gc is making the interpreter fail to load.

This issue was handled by @ambv in #130418, but that fix had an issue with not detecting the iPad correctly.
In iPad + Safari, iPad behaves like a Mac and checking iPad string in navigator.platform fails to detect iPad.

Confirmed on device + downstream PR (pyodide/pyodide#5695)

cc: @hoodmane @WebReflection

Issue: Emscripten: Use wasm-gc for call trampolines instead of JS type reflection #128627

bedevere-app · 2025-06-11T13:25:04Z

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If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

hoodmane · 2025-06-11T16:07:55Z

While we're at it maybe let's add links to the relevant webkit issue and the fix:
https://bugs.webkit.org/show_bug.cgi?id=293113
WebKit/WebKit#46379

hoodmane · 2025-06-11T16:08:37Z

Otherwise looks good to me. Thanks @ryanking13!

hoodmane · 2025-06-11T16:10:50Z

Maybe we should also add a comment saying this code is only needed to make jspi work and since jspi is not yet supported on Safari it would be okay to turn it off for desktop Safari as well if we need to.

hoodmane

Thanks!

WebReflection · 2025-06-11T20:05:10Z

+ // Starting with iPadOS 13, iPads might send a platform string that looks like a desktop Mac.
+ // To differentiate, we check if the platform is 'MacIntel' (common for Macs and newer iPads)
+ // AND if the device has multi-touch capabilities (navigator.maxTouchPoints > 1)
+ (navigator.platform === 'MacIntel' && typeof navigator.maxTouchPoints !== 'undefined' && navigator.maxTouchPoints > 1)


duplicated same-comment here: pyodide/pyodide#5695 (review)

freakboy3742

Added in a reference to the radar and CPython issues, but otherwise, LGTM.

miss-islington-app · 2025-06-12T04:04:16Z

Thanks @ryanking13 for the PR, and @freakboy3742 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

On some iPad versions, Safari reports as "macOS". Modifies the GC trampoline detection to add a feature-based check to detect this case. (cherry picked from commit d447129) Co-authored-by: Gyeongjae Choi <def6488@gmail.com>

bedevere-app · 2025-06-12T04:04:26Z

GH-135419 is a backport of this pull request to the 3.14 branch.

On some iPad versions, Safari reports as "macOS". Modifies the GC trampoline detection to add a feature-based check to detect this case. (cherry picked from commit d447129) Co-authored-by: Gyeongjae Choi <def6488@gmail.com>

bedevere-bot · 2025-06-12T05:55:35Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 RHEL8 Refleaks 3.14 (tier-1) has failed when building commit e76dbc8.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1795/builds/170) and take a look at the build logs.
Check if the failure is related to this commit (e76dbc8) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1795/builds/170

Failed tests:

test.test_multiprocessing_fork.test_processes

Failed subtests:

test_interrupt - test.test_multiprocessing_fork.test_processes.WithProcessesTestProcess.test_interrupt

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 588, in test_interrupt
exitcode =self._kill_process(multiprocessing.Process.interrupt)
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 570, in _kill_processself.assertEqual(join(), None)
~~~~^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__returnself.func(*args, **kwds)
~~~~~~~~~^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
res =self._popen.wait(timeout)
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in waitreturnself.poll(os.WNOHANGif timeout ==0.0else0)
~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
pid, sts = os.waitpid(self.pid, flag)
~~~~~~~~~~^^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 566, in handlerraiseRuntimeError('join took too long: %s'% p)
RuntimeError: join took too long: <Process name='Process-931' pid=3787289 parent=3781804 started daemon>
Traceback (most recent call last):
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 588, in test_interrupt
exitcode =self._kill_process(multiprocessing.Process.interrupt)
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 570, in _kill_processself.assertEqual(join(), None)
~~~~^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__returnself.func(*args, **kwds)
~~~~~~~~~^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
res =self._popen.wait(timeout)
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in waitreturnself.poll(os.WNOHANGif timeout ==0.0else0)
~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
pid, sts = os.waitpid(self.pid, flag)
~~~~~~~~~~^^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 566, in handlerraiseRuntimeError('join took too long: %s'% p)
RuntimeError: join took too long: <Process name='Process-3' pid=3894134 parent=3894130 started daemon>
Traceback (most recent call last):
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 320, in _bootstrapself.run()
~~~~~~~~^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/multiprocessing/process.py", line 108, in runself._target(*self._args, **self._kwargs)
~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/buildbot/buildarea/3.14.cstratak-RHEL8-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 518, in _sleep_some_event
time.sleep(100)
~~~~~~~~~~^^^^^
KeyboardInterrupt
k

freakboy3742 · 2025-06-12T07:27:59Z

Buildbot failure is a false positive.

On some iPad versions, Safari reports as "macOS". Modifies the GC trampoline detection to add a feature-based check to detect this case.

Fix iPad detection in wasm-gc
486bd2b

bedevere-appBot added the awaiting review label Jun 11, 2025

bedevere-appBot mentioned this pull request Jun 11, 2025
Emscripten: Use wasm-gc for call trampolines instead of JS type reflection #128627
Closed

ryanking13 mentioned this pull request Jun 11, 2025
Fix iPad detection in wasm-gc pyodide/pyodide#5695
Merged
1 task

hoodmane added the skip news label Jun 11, 2025

hoodmane requested a review from freakboy3742 June 11, 2025 16:08

hoodmane approved these changes Jun 11, 2025
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bedevere-appBot added awaiting core review and removed awaiting review labels Jun 11, 2025

WebReflection reviewed Jun 11, 2025
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freakboy3742 added the needs backport to 3.14 bugs and security fixes label Jun 12, 2025

freakboy3742 approved these changes Jun 12, 2025
View reviewed changes

Comment threadPython/emscripten_trampoline.c

bedevere-appBot added awaiting merge and removed awaiting core review labels Jun 12, 2025

Add a comment about why this special case is needed.
35b6c64

freakboy3742 enabled auto-merge (squash) June 12, 2025 03:38

freakboy3742 merged commit d447129 into python:mainJun 12, 2025

bedevere-appBot removed the awaiting merge label Jun 12, 2025

bedevere-appBot removed the needs backport to 3.14 bugs and security fixes label Jun 12, 2025

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gh-128627: Fix iPad detection in wasm-gc - #135388

gh-128627: Fix iPad detection in wasm-gc#135388
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ryanking13:fix-ipad-detection

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