[embind] Fix typo in overloadTable error checking. NFC (#22715)

Author: sbc100

src/embind/embind.js

@@ -124,17 +124,14 @@ var LibraryEmbind = {
       // We are exposing a function with the same name as an existing function. Create an overload table and a function selector
       // that routes between the two.
       ensureOverloadTable(Module, name, name);
-      if (Module.hasOwnProperty(numArguments)) {
+      if (Module[name].overloadTable.hasOwnProperty(numArguments)) {
         throwBindingError(`Cannot register multiple overloads of a function with the same number of arguments (${numArguments})!`);
       }
       // Add the new function into the overload table.
       Module[name].overloadTable[numArguments] = value;
-    }
-    else {
+    } else {
       Module[name] = value;
-      if (undefined !== numArguments) {
-        Module[name].numArguments = numArguments;
-      }
+      Module[name].argCount = numArguments;
     }
   },
 
@@ -147,8 +144,7 @@ var LibraryEmbind = {
     // If there's an overload table for this symbol, replace the symbol in the overload table instead.
     if (undefined !== Module[name].overloadTable && undefined !== numArguments) {
       Module[name].overloadTable[numArguments] = value;
-    }
-    else {
+    } else {
       Module[name] = value;
       Module[name].argCount = numArguments;
     }

test/code_size/embind_hello_wasm.json

@@ -1,10 +1,10 @@
 {
   "a.html": 552,
   "a.html.gz": 380,
-  "a.js": 9727,
-  "a.js.gz": 4295,
+  "a.js": 9718,
+  "a.js.gz": 4291,
   "a.wasm": 7730,
   "a.wasm.gz": 3507,
-  "total": 18009,
-  "total_gz": 8182
+  "total": 18000,
+  "total_gz": 8178
 }

test/embind/test_embind_invalid_overload.cpp

@@ -0,0 +1,22 @@
+#include <functional>
+#include <emscripten/bind.h>
+
+using namespace emscripten;
+
+int main() {
+}
+
+int foo(int a) {
+  return 0;
+}
+
+int foo(float a) {
+  return 0;
+}
+
+EMSCRIPTEN_BINDINGS(bindings) {
+  // Overloads in embind all need to have a unique number of arguments.
+  // This is invalid since both overloads take just one argument.
+  function("foo", select_overload<int(int)>(&foo));
+  function("foo", select_overload<int(float)>(&foo));
+}

test/test_other.py

@@ -3127,6 +3127,10 @@ def test_embind_fail(self):
     out = self.expect_fail([EMXX, test_file('embind/test_unsigned.cpp')])
     self.assertContained("undefined symbol: _embind_register_function", out)
 
+  def test_embind_invalid_overload(self):
+    expected = 'BindingError: Cannot register multiple overloads of a function with the same number of arguments'
+    self.do_runf(test_file('embind/test_embind_invalid_overload.cpp'), expected, emcc_args=['-lembind'], assert_returncode=NON_ZERO)
+
   def test_embind_asyncify(self):
     create_file('post.js', '''
       addOnPostRun(() => {