[EH] Warn for ASYNCIFY + -fwasm-exceptions (#18635)

This combination is currently not supported.

Author: aheejin

emcc.py

@@ -1595,6 +1595,8 @@ def phase_setup(options, state, newargs):
       exit_with_error('DISABLE_EXCEPTION_CATCHING is not compatible with -fwasm-exceptions')
     if 'DISABLE_EXCEPTION_THROWING' in user_settings:
       exit_with_error('DISABLE_EXCEPTION_THROWING is not compatible with -fwasm-exceptions')
+    if 'ASYNCIFY' in user_settings and user_settings['ASYNCIFY'] == '1':
+      diagnostics.warning('emcc', 'ASYNCIFY=1 is not compatible with -fwasm-exceptions. Parts of the program that mix ASYNCIFY and exceptions will not compile.')
     settings.DISABLE_EXCEPTION_CATCHING = 1
     settings.DISABLE_EXCEPTION_THROWING = 1