[Asyncify] Hint at the stack size possibly being the issue when hitting "unreachable" (#18085)

Helps #17567

Also move the test from the browser suite to other. It's easier to test there and it's faster.

Author: kripken

src/preamble.js

@@ -482,6 +482,10 @@ function abort(what) {
 
 #if ASSERTIONS == 0
   what += '. Build with -sASSERTIONS for more info.';
+#elif ASYNCIFY == 1
+  if (what.indexOf('RuntimeError: unreachable') >= 0) {
+    what += '. "unreachable" may be due to ASYNCIFY_STACK_SIZE not being large enough (try increasing it)';
+  }
 #endif // ASSERTIONS
 
   // Use a wasm runtime error, because a JS error might be seen as a foreign

test/browser/async_stack_overflow.cpp renamed to test/other/test_asyncify_stack_overflow.cpp

@@ -17,7 +17,5 @@ int main(int argc, char* argv[]) {
   // We should not get here - the unwind will fail as the stack is too small
   printf("We should not get here %d %d %d\n", x, y, z);
 
-  REPORT_RESULT(1);
-
   return 0;
 }

test/test_browser.py

@@ -3366,9 +3366,6 @@ def test_async_returnvalue(self, args):
       create_file('filey.txt', 'sync_tunnel\nsync_tunnel_bool\n')
     self.btest('browser/async_returnvalue.cpp', '0', args=['-sASYNCIFY', '-sASYNCIFY_IGNORE_INDIRECT', '--js-library', test_file('browser/async_returnvalue.js')] + args + ['-sASSERTIONS'])
 
-  def test_async_stack_overflow(self):
-    self.btest('browser/async_stack_overflow.cpp', 'abort:RuntimeError: unreachable', args=['-sASYNCIFY', '-sASYNCIFY_STACK_SIZE=4'])
-
   def test_async_bad_list(self):
     self.btest('browser/async_bad_list.cpp', '0', args=['-sASYNCIFY', '-sASYNCIFY_ONLY=[waka]', '--profiling'])
 

test/test_other.py

@@ -9182,6 +9182,24 @@ def test_asyncify_advise(self):
     self.assertContained('[asyncify] g can', out)
     self.assertContained('[asyncify] i can', out)
 
+  def test_asyncify_stack_overflow(self):
+    self.emcc_args = ['-sASYNCIFY', '-sASYNCIFY_STACK_SIZE=4']
+
+    # The unreachable error on small stack sizes is not super-helpful. Try at
+    # least to hint at increasing the stack size.
+
+    def test(args, expected):
+      self.do_runf(test_file('other/test_asyncify_stack_overflow.cpp'),
+                   emcc_args=args,
+                   assert_returncode=common.NON_ZERO,
+                   expected_output=[expected])
+
+    test(['-sASSERTIONS=0'],
+         'Aborted(RuntimeError: unreachable). Build with -sASSERTIONS for more info.')
+
+    test(['-sASSERTIONS=1'],
+         'Aborted(RuntimeError: unreachable). "unreachable" may be due to ASYNCIFY_STACK_SIZE not being large enough (try increasing it)')
+
   # Sockets and networking
 
   def test_inet(self):