more than one touch asserts emscripten_set_touchmove_callback callback

[lpotter]

More than one active touch crashes emscripten_set_touchmove_callback
(no other callbacks crash)

Using 2.0.9 with this simple example:
`
#include
#include <emscripten/html5.h>

EM_BOOL touchmove_callback(int, EmscriptenTouchEvent const touchEvent, void) {
static int i = 0;
std::cout << touchEvent->numTouches << std::endl;
return EM_FALSE;
}

int main(int const, char const* const []) {
emscripten_set_touchmove_callback("#canvas", nullptr, 1, touchmove_callback);
return 0;
}
`

[kripken]

What error do you see?

That program doesn't seem to compile - it is missing at least #include iostream, but even with that it errors for me on a few things, starting with error: 'void' must be the first and only parameter if specified.

Also I assume this needs some pattern of input to trigger the bug - it would be good if the testcase can create events to cause the bug automatically.

[lpotter]

Actually, the iostream is there when I edit that description, but seems to be hidden by the html, as are the * in the appropriate places in the function arguments.
It does not seem to let me attach .cpp file.

Not sure how I would code simple 'two fingers touch on touchscreen'.
One finger works fine, as does 1.39.8. Other callbacks work fine with more than one finger point too.

Here is the console message:

Assertion failed: undefined em_touch.html:1246:19 printErr http://192.168.1.123:8000/em_touch.html:1246 abort http://192.168.1.123:8000/em_touch.js:1392 assert http://192.168.1.123:8000/em_touch.js:588 touchEventHandlerFunc http://192.168.1.123:8000/em_touch.js:1851 jsEventHandler http://192.168.1.123:8000/em_touch.js:1788 (Async: EventListener.handleEvent) registerOrRemoveHandler http://192.168.1.123:8000/em_touch.js:1797 __registerTouchEventCallback http://192.168.1.123:8000/em_touch.js:1910 _emscripten_set_touchmove_callback_on_thread http://192.168.1.123:8000/em_touch.js:1913 http://192.168.1.123:8000/em_touch.wasm:4055 createExportWrapper http://192.168.1.123:8000/em_touch.js:1454 callMain http://192.168.1.123:8000/em_touch.js:5144 doRun http://192.168.1.123:8000/em_touch.js:5208 run http://192.168.1.123:8000/em_touch.js:5219 (Async: setTimeout handler) run http://192.168.1.123:8000/em_touch.js:5215 runCaller http://192.168.1.123:8000/em_touch.js:5122 removeRunDependency http://192.168.1.123:8000/em_touch.js:1377 receiveInstance http://192.168.1.123:8000/em_touch.js:1520 receiveInstantiatedSource http://192.168.1.123:8000/em_touch.js:1536 (Async: promise callback) instantiateAsync http://192.168.1.123:8000/em_touch.js:1559 (Async: promise callback) instantiateAsync http://192.168.1.123:8000/em_touch.js:1557 createWasm http://192.168.1.123:8000/em_touch.js:1584 http://192.168.1.123:8000/em_touch.js:4873 Uncaught Error: undefined em_touch.js:1403:11 abort http://192.168.1.123:8000/em_touch.js:1403 assert http://192.168.1.123:8000/em_touch.js:588 touchEventHandlerFunc http://192.168.1.123:8000/em_touch.js:1851 jsEventHandler http://192.168.1.123:8000/em_touch.js:1788 (Async: EventListener.handleEvent) registerOrRemoveHandler http://192.168.1.123:8000/em_touch.js:1797 __registerTouchEventCallback http://192.168.1.123:8000/em_touch.js:1910 _emscripten_set_touchmove_callback_on_thread http://192.168.1.123:8000/em_touch.js:1913 http://192.168.1.123:8000/em_touch.wasm:4055 createExportWrapper http://192.168.1.123:8000/em_touch.js:1454 callMain http://192.168.1.123:8000/em_touch.js:5144 doRun http://192.168.1.123:8000/em_touch.js:5208 run http://192.168.1.123:8000/em_touch.js:5219 (Async: setTimeout handler) run http://192.168.1.123:8000/em_touch.js:5215 runCaller http://192.168.1.123:8000/em_touch.js:5122 removeRunDependency http://192.168.1.123:8000/em_touch.js:1377 receiveInstance http://192.168.1.123:8000/em_touch.js:1520 receiveInstantiatedSource http://192.168.1.123:8000/em_touch.js:1536 (Async: promise callback) instantiateAsync http://192.168.1.123:8000/em_touch.js:1559 (Async: promise callback) instantiateAsync http://192.168.1.123:8000/em_touch.js:1557 createWasm http://192.168.1.123:8000/em_touch.js:1584 http://192.168.1.123:8000/em_touch.js:4873

[yymrennie]

I got the same problem but for me it occurs on single touches as well, and seemingly occurs on all touch events. I hit the same asserts as mentioned in bug #14064. This was tested on a Windows 10 tablet using Emscripten 2.0.25 and was tested on Firefox 90.0 and Edge 91.0.864.70 with the problem happening on both.

For the moment we've disabled assertions to work around this but it isn't an ideal solution.

[adam4235]

As mentioned in #14064, I think this might be fixed now?