Allow dollar sign in export names (emscripten-core#24367)

Fixes: emscripten-core#24363

Author: sbc100

test/test_other.py

@@ -15936,6 +15936,14 @@ def test_invalid_export_name(self):
     err = self.expect_fail([EMCC, 'test.c'])
     self.assertContained('emcc: error: invalid export name: my.func', err)
 
+    # GCC (and clang) and JavaScript also allow $ in symbol names
+    create_file('valid.c', '''
+                #include <emscripten.h>
+                EMSCRIPTEN_KEEPALIVE
+                void my$func() {}
+                ''')
+    self.run_process([EMCC, 'valid.c'])
+
   @also_with_modularize
   def test_instantiate_wasm(self):
     create_file('pre.js', '''

tools/emscripten.py

@@ -16,6 +16,7 @@
 import subprocess
 import logging
 import pprint
+import re
 import shutil
 import sys
 import textwrap
@@ -455,6 +456,13 @@ def get_metadata(infile, outfile, modify_wasm, args):
   return metadata
 
 
+def is_valid_js_identifier(ident):
+  # See https://developer.mozilla.org/en-US/docs/Glossary/Identifier
+  if ident[0].isdigit():
+    return False
+  return re.fullmatch(r'[0-9a-zA-Z_\$]+', ident)
+
+
 def finalize_wasm(infile, outfile, js_syms):
   building.save_intermediate(infile, 'base.wasm')
   args = []
@@ -563,7 +571,7 @@ def finalize_wasm(infile, outfile, js_syms):
   # not known auto-generated system functions.
   unexpected_exports = [e for e in metadata.all_exports if shared.is_user_export(e)]
   for n in unexpected_exports:
-    if not n.isidentifier():
+    if not is_valid_js_identifier(n):
       exit_with_error(f'invalid export name: {n}')
   unexpected_exports = [asmjs_mangle(e) for e in unexpected_exports]
   unexpected_exports = [e for e in unexpected_exports if e not in expected_exports]