We currently allow stack overflow exceptions from within wasm code to be caught by a catch_all block, which does not match v8. Wasm stack overflows are specified to be the same type as JS stack overflows: https://webassembly.github.io/exception-handling/js-api/index.html#js-exceptions The proposal says that these are not catchable: https://github.com/WebAssembly/exception-handling/issues/202 But I cannot find that this is specified in the formal spec: https://webassembly.github.io/exception-handling/js-api/index.html#errors We are probably doing the wrong thing here, but maybe we should file a spec bug too.
<rdar://problem/96459590>
As far as I can tell from https://github.com/WebAssembly/exception-handling/issues/202 it seems like we're doing the right thing already. "#218 (comment) basically says, if JS throws an exception and it passes through Wasm (either by not being caught or being caught and rethrown) the exception object you will get is the same as the one you threw." Seems to imply that JS exceptions should be catchall-able.