Add assertions on missing Wasm exports. NFC (#25541)

Author: sbc100

test/codesize/test_codesize_hello_O0.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 23198,
-  "a.out.js.gz": 8525,
+  "a.out.js": 24070,
+  "a.out.js.gz": 8666,
   "a.out.nodebug.wasm": 15127,
   "a.out.nodebug.wasm.gz": 7450,
-  "total": 38325,
-  "total_gz": 15975,
+  "total": 39197,
+  "total_gz": 16116,
   "sent": [
     "fd_write"
   ],

test/codesize/test_codesize_minimal_O0.expected.js

@@ -1319,16 +1319,27 @@ var __indirect_function_table = makeInvalidEarlyAccess('__indirect_function_tabl
 var wasmMemory = makeInvalidEarlyAccess('wasmMemory');
 
 function assignWasmExports(wasmExports) {
+  assert(wasmExports['add'], 'missing Wasm export: add');
   _add = Module['_add'] = createExportWrapper('add', 2);
+  assert(wasmExports['fflush'], 'missing Wasm export: fflush');
   _fflush = createExportWrapper('fflush', 1);
+  assert(wasmExports['emscripten_stack_init'], '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');
   _emscripten_stack_get_free = wasmExports['emscripten_stack_get_free'];
+  assert(wasmExports['emscripten_stack_get_base'], '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');
   _emscripten_stack_get_end = wasmExports['emscripten_stack_get_end'];
+  assert(wasmExports['_emscripten_stack_restore'], 'missing Wasm export: _emscripten_stack_restore');
   __emscripten_stack_restore = wasmExports['_emscripten_stack_restore'];
+  assert(wasmExports['_emscripten_stack_alloc'], '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');
   _emscripten_stack_get_current = wasmExports['emscripten_stack_get_current'];
+  assert(wasmExports['memory'], 'missing Wasm export: memory');
   memory = wasmMemory = wasmExports['memory'];
+  assert(wasmExports['__indirect_function_table'], '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": 18466,
-  "a.out.js.gz": 6834,
+  "a.out.js": 19262,
+  "a.out.js.gz": 6966,
   "a.out.nodebug.wasm": 1136,
   "a.out.nodebug.wasm.gz": 659,
-  "total": 19602,
-  "total_gz": 7493,
+  "total": 20398,
+  "total_gz": 7625,
   "sent": [],
   "imports": [],
   "exports": [

test/codesize/test_unoptimized_code_size.json

@@ -1,16 +1,16 @@
 {
-  "hello_world.js": 55502,
-  "hello_world.js.gz": 17496,
+  "hello_world.js": 56566,
+  "hello_world.js.gz": 17601,
   "hello_world.wasm": 15127,
   "hello_world.wasm.gz": 7450,
   "no_asserts.js": 26608,
   "no_asserts.js.gz": 8874,
   "no_asserts.wasm": 12227,
   "no_asserts.wasm.gz": 6010,
-  "strict.js": 53517,
-  "strict.js.gz": 16822,
+  "strict.js": 54581,
+  "strict.js.gz": 16947,
   "strict.wasm": 15127,
   "strict.wasm.gz": 7447,
-  "total": 178108,
-  "total_gz": 64099
+  "total": 180236,
+  "total_gz": 64329
 }

tools/emscripten.py

@@ -991,6 +991,8 @@ def create_receiving(function_exports, other_exports, library_symbols, aliases):
       assignment += f" = dynCalls['{sig_str}']"
     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}');")
     if sym in alias_inverse_map:
       for target in alias_inverse_map[sym]:
         assignment += f" = {target}"