Fix LZ4 file packaging support when MODULARIZE=1 (#13161)

This is based on work by @mdboom in #7107

AUTHORS

@@ -533,4 +533,5 @@ a license to everyone to use it as detailed in LICENSE.)
 * Aleksey Kliger <aleksey@lambdageek.org> (copyright owned by Microsoft, Inc.)
 * Nicolas Ollinger <nopid@free.fr>
 * Michael R. Crusoe <crusoe@debian.org>
+* Dexter Chua <dec41@srcf.net>
 * Thomas Ballinger <thomasballinger@gmail.com>

emcc.py

@@ -1148,6 +1148,9 @@ There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR P
       # we also do not support standalone mode in fastcomp.
       shared.Settings.STANDALONE_WASM = 1
 
+    if shared.Settings.LZ4:
+      shared.Settings.EXPORTED_RUNTIME_METHODS += ['LZ4']
+
     if shared.Settings.WASM2C:
       # wasm2c only makes sense with standalone wasm - there will be no JS,
       # just wasm and then C

tests/test_browser.py

@@ -1383,6 +1383,15 @@ keydown(100);keyup(100); // trigger the end
     self.btest(os.path.join('fs', 'test_lz4fs.cpp'), '2', args=['--pre-js', 'files.js', '-s', 'LZ4=1', '-s', 'FORCE_FILESYSTEM'])
     print('    opts')
     self.btest(os.path.join('fs', 'test_lz4fs.cpp'), '2', args=['--pre-js', 'files.js', '-s', 'LZ4=1', '-s', 'FORCE_FILESYSTEM', '-O2'])
+    print('    modularize')
+    self.compile_btest([path_from_root('tests', 'fs', 'test_lz4fs.cpp'), '--pre-js', 'files.js', '-s', 'LZ4=1', '-s', 'FORCE_FILESYSTEM', '-s', 'MODULARIZE=1'])
+    create_test_file('a.html', '''
+      <script src="a.out.js"></script>
+      <script>
+        Module()
+      </script>
+    ''')
+    self.run_browser('a.html', '.', '/report_result?2')
 
     # load the data into LZ4FS manually at runtime. This means we compress on the client. This is generally not recommended
     print('manual')

tools/file_packager.py

@@ -514,8 +514,8 @@ def main():
       use_data = '''
             var compressedData = %s;
             compressedData['data'] = byteArray;
-            assert(typeof LZ4 === 'object', 'LZ4 not present - was your app build with  -s LZ4=1  ?');
-            LZ4.loadPackage({ 'metadata': metadata, 'compressedData': compressedData });
+            assert(typeof Module.LZ4 === 'object', 'LZ4 not present - was your app build with  -s LZ4=1  ?');
+            Module.LZ4.loadPackage({ 'metadata': metadata, 'compressedData': compressedData });
             Module['removeRunDependency']('datafile_%s');
       ''' % (meta, shared.JS.escape_for_js_string(data_target))