Improve missing export assertion. NFC (#25601)

Author: sbc100

test/codesize/test_codesize_hello_O0.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 24070,
-  "a.out.js.gz": 8666,
+  "a.out.js": 24334,
+  "a.out.js.gz": 8676,
   "a.out.nodebug.wasm": 15119,
   "a.out.nodebug.wasm.gz": 7444,
-  "total": 39189,
-  "total_gz": 16110,
+  "total": 39453,
+  "total_gz": 16120,
   "sent": [
     "fd_write"
   ],

test/codesize/test_codesize_minimal_O0.expected.js

@@ -1320,27 +1320,27 @@ var __indirect_function_table = makeInvalidEarlyAccess('__indirect_function_tabl
 var wasmMemory = makeInvalidEarlyAccess('wasmMemory');
 
 function assignWasmExports(wasmExports) {
-  assert(wasmExports['add'], 'missing Wasm export: add');
+  assert(typeof wasmExports['add'] != 'undefined', 'missing Wasm export: add');
   _add = Module['_add'] = createExportWrapper('add', 2);
-  assert(wasmExports['fflush'], 'missing Wasm export: fflush');
+  assert(typeof wasmExports['fflush'] != 'undefined', 'missing Wasm export: fflush');
   _fflush = createExportWrapper('fflush', 1);
-  assert(wasmExports['emscripten_stack_init'], 'missing Wasm export: emscripten_stack_init');
+  assert(typeof wasmExports['emscripten_stack_init'] != 'undefined', 'missing Wasm export: emscripten_stack_init');
   _emscripten_stack_init = wasmExports['emscripten_stack_init'];
-  assert(wasmExports['emscripten_stack_get_free'], 'missing Wasm export: emscripten_stack_get_free');
+  assert(typeof wasmExports['emscripten_stack_get_free'] != 'undefined', 'missing Wasm export: emscripten_stack_get_free');
   _emscripten_stack_get_free = wasmExports['emscripten_stack_get_free'];
-  assert(wasmExports['emscripten_stack_get_base'], 'missing Wasm export: emscripten_stack_get_base');
+  assert(typeof wasmExports['emscripten_stack_get_base'] != 'undefined', 'missing Wasm export: emscripten_stack_get_base');
   _emscripten_stack_get_base = wasmExports['emscripten_stack_get_base'];
-  assert(wasmExports['emscripten_stack_get_end'], 'missing Wasm export: emscripten_stack_get_end');
+  assert(typeof wasmExports['emscripten_stack_get_end'] != 'undefined', 'missing Wasm export: emscripten_stack_get_end');
   _emscripten_stack_get_end = wasmExports['emscripten_stack_get_end'];
-  assert(wasmExports['_emscripten_stack_restore'], 'missing Wasm export: _emscripten_stack_restore');
+  assert(typeof wasmExports['_emscripten_stack_restore'] != 'undefined', 'missing Wasm export: _emscripten_stack_restore');
   __emscripten_stack_restore = wasmExports['_emscripten_stack_restore'];
-  assert(wasmExports['_emscripten_stack_alloc'], 'missing Wasm export: _emscripten_stack_alloc');
+  assert(typeof wasmExports['_emscripten_stack_alloc'] != 'undefined', 'missing Wasm export: _emscripten_stack_alloc');
   __emscripten_stack_alloc = wasmExports['_emscripten_stack_alloc'];
-  assert(wasmExports['emscripten_stack_get_current'], 'missing Wasm export: emscripten_stack_get_current');
+  assert(typeof wasmExports['emscripten_stack_get_current'] != 'undefined', 'missing Wasm export: emscripten_stack_get_current');
   _emscripten_stack_get_current = wasmExports['emscripten_stack_get_current'];
-  assert(wasmExports['memory'], 'missing Wasm export: memory');
+  assert(typeof wasmExports['memory'] != 'undefined', 'missing Wasm export: memory');
   memory = wasmMemory = wasmExports['memory'];
-  assert(wasmExports['__indirect_function_table'], 'missing Wasm export: __indirect_function_table');
+  assert(typeof wasmExports['__indirect_function_table'] != 'undefined', 'missing Wasm export: __indirect_function_table');
   __indirect_function_table = wasmExports['__indirect_function_table'];
 }
 

test/codesize/test_codesize_minimal_O0.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 19262,
-  "a.out.js.gz": 6966,
+  "a.out.js": 19504,
+  "a.out.js.gz": 6976,
   "a.out.nodebug.wasm": 1136,
   "a.out.nodebug.wasm.gz": 659,
-  "total": 20398,
-  "total_gz": 7625,
+  "total": 20640,
+  "total_gz": 7635,
   "sent": [],
   "imports": [],
   "exports": [

test/codesize/test_unoptimized_code_size.json

@@ -1,16 +1,16 @@
 {
-  "hello_world.js": 56592,
-  "hello_world.js.gz": 17608,
+  "hello_world.js": 56856,
+  "hello_world.js.gz": 17627,
   "hello_world.wasm": 15119,
   "hello_world.wasm.gz": 7444,
   "no_asserts.js": 26634,
   "no_asserts.js.gz": 8883,
   "no_asserts.wasm": 12219,
   "no_asserts.wasm.gz": 6005,
-  "strict.js": 54607,
-  "strict.js.gz": 16955,
+  "strict.js": 54871,
+  "strict.js.gz": 16967,
   "strict.wasm": 15119,
   "strict.wasm.gz": 7442,
-  "total": 180290,
-  "total_gz": 64337
+  "total": 180818,
+  "total_gz": 64368
 }

tools/emscripten.py

@@ -993,7 +993,7 @@ def create_receiving(function_exports, other_exports, library_symbols, aliases):
     if do_module_exports and should_export(mangled):
       assignment += f" = Module['{mangled}']"
     if settings.ASSERTIONS:
-      receiving.append(f"  assert(wasmExports['{sym}'], 'missing Wasm export: {sym}');")
+      receiving.append(f"  assert(typeof wasmExports['{sym}'] != 'undefined', 'missing Wasm export: {sym}');")
     if sym in alias_inverse_map:
       for target in alias_inverse_map[sym]:
         assignment += f" = {target}"