Fix --post-link combined with -s flags (#24270)

Fixes: #24250

Author: sbc100

emcc.py

@@ -1047,6 +1047,8 @@ def parse_args(newargs):  # noqa: C901, PLR0912, PLR0915
       # because that next arg could, for example, start with `-o` and we don't want
       # to confuse that with a normal `-o` flag.
       skip = True
+    elif arg == '-s' and is_dash_s_for_emcc(newargs, i):
+      skip = True
 
     def check_flag(value):
       # Check for and consume a flag

test/test_other.py

@@ -13417,7 +13417,9 @@ def test_closure_safe(self, args):
   def test_post_link(self):
     err = self.run_process([EMCC, test_file('hello_world.c'), '--oformat=bare', '-o', 'bare.wasm'], stderr=PIPE).stderr
     self.assertContained('--oformat=bare/--post-link are experimental and subject to change', err)
-    err = self.run_process([EMCC, '--post-link', 'bare.wasm'], stderr=PIPE).stderr
+    # Explicitly test with `-s RUNTIME_DEBUG`, including the space, to verify parsing of `-s` flags
+    # See https://github.com/emscripten-core/emscripten/issues/24250
+    err = self.run_process([EMCC, '--post-link', 'bare.wasm', '-s', 'RUNTIME_DEBUG'], stderr=PIPE).stderr
     self.assertContained('--oformat=bare/--post-link are experimental and subject to change', err)
     err = self.assertContained('hello, world!', self.run_js('a.out.js'))