Make ASSERTIONS=2 imply STACK_OVERFLOW_CHECK=2 (#12579)

This is in addition to the existing 1 implying 1.

The goal is to make it easier to use -s ASSERTIONS=2 and have it check
as many things as possible.

ChangeLog.md

@@ -20,6 +20,8 @@ See docs/process.md for more on how version tagging works.
 
 Current Trunk
 -------------
+- `-s ASSERTIONS=2` now implies `-s STACK_OVERFLOW_CHECK=2`. Previously only
+  `-s ASSERTIONS=1` implied `-s STACK_OVERFLOW_CHECK=1`.
 - Dynamic linking (MAIN_MODULE + SIDE_MODULE) now produces wasm binaries that
   depend on mutable globals.  Specifically the stack pointer global is mutable
   and shared between the modules. This is an ABI change for dynamic linking.

emcc.py

@@ -1236,9 +1236,11 @@ There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR P
     # Note the exports the user requested
     building.user_requested_exports = shared.Settings.EXPORTED_FUNCTIONS[:]
 
-    # -s ASSERTIONS=1 implies basic stack overflow checks.
-    if shared.Settings.ASSERTIONS:
-      shared.Settings.STACK_OVERFLOW_CHECK = max(1, shared.Settings.STACK_OVERFLOW_CHECK)
+    # -s ASSERTIONS=1 implies basic stack overflow checks, and ASSERTIONS=2
+    # implies full stack overflow checks (unless the user specifically set
+    # something else)
+    if shared.Settings.ASSERTIONS and 'STACK_OVERFLOW_CHECK' not in settings_key_changes:
+      shared.Settings.STACK_OVERFLOW_CHECK = max(shared.Settings.ASSERTIONS, shared.Settings.STACK_OVERFLOW_CHECK)
 
     if shared.Settings.LLD_REPORT_UNDEFINED or shared.Settings.STANDALONE_WASM:
       # Reporting undefined symbols at wasm-ld time requires us to know if we have a `main` function

tests/test_core.py

@@ -7692,6 +7692,11 @@ NODEFS is no longer included by default; build with -lnodefs.js
     self.emcc_args += ['-DONE_BIG_STRING']
     self.do_runf(path_from_root('tests', 'stack_overflow.cpp'), 'stack overflow', assert_returncode=NON_ZERO)
 
+    # ASSERTIONS=2 implies STACK_OVERFLOW_CHECK=2
+    self.clear_setting('STACK_OVERFLOW_CHECK')
+    self.set_setting('ASSERTIONS', 2)
+    self.do_runf(path_from_root('tests', 'stack_overflow.cpp'), 'stack overflow', assert_returncode=NON_ZERO)
+
   @node_pthreads
   def test_binaryen_2170_emscripten_atomic_cas_u8(self):
     self.emcc_args += ['-s', 'USE_PTHREADS=1']