Add wasm-bindgen support

src/preamble.js

@@ -908,6 +908,7 @@ function getWasmImports() {
 #else // MINIFY_WASM_IMPORTED_MODULES
     'env': wasmImports,
     '{{{ WASI_MODULE_NAME }}}': wasmImports,
+    'wbg': wasmImports,
 #endif // MINIFY_WASM_IMPORTED_MODULES
 #if SPLIT_MODULE
     'placeholder': new Proxy({}, splitModuleProxyHandler),

src/settings.js

@@ -2186,6 +2186,10 @@ var LEGACY_RUNTIME = false;
 // [link]
 var SIGNATURE_CONVERSIONS = [];
 
+// Run wasm-bindgen and integrate the rust-exported symbols into the rest of Emscripten's JS output.
+// [link]
+var WASM_BINDGEN = 0;
+
 // For renamed settings the format is:
 // [OLD_NAME, NEW_NAME]
 // For removed settings (which now effectively have a fixed value and can no

tools/building.py

@@ -1232,6 +1232,27 @@ def run_wasm_opt(infile, outfile=None, args=[], **kwargs):  # noqa
   return run_binaryen_command('wasm-opt', infile, outfile, args=args, **kwargs)
 
 
+def run_wasm_bindgen(infile, outfile=None, args=[], **kwargs):  # noqa
+  if not os.path.exists(infile):
+    exit_with_error('wasm-bindgen: wasm file not found (%s).' % infile)
+
+  cmd = config.WASM_BINDGEN + [
+    infile,
+    '--target',
+    'emscripten',
+    '--keep-lld-exports',
+    '--out-dir',
+    get_emscripten_temp_dir() + '/wbg_out'
+  ]
+  ret = check_call(cmd).stdout
+  new_wasm_file = get_emscripten_temp_dir() + '/wbg_out/' + os.path.basename(infile).split('.')[0] + '.wasm'
+  if outfile == None:
+    outfile = infile
+  check_call(['cp', new_wasm_file, infile])
+
+  return ret
+
+
 def save_intermediate(src, dst):
   if DEBUG:
     dst = 'emcc-%02d-%s' % (save_intermediate.counter, dst)

tools/config.py

@@ -36,6 +36,7 @@
 CACHE = None
 PORTS = None
 COMPILER_WRAPPER = None
+WASM_BINDGEN = None
 
 # Set by init()
 EM_CONFIG = None
@@ -58,6 +59,7 @@ def fix_js_engine(old, new):
 def normalize_config_settings():
   global CACHE, PORTS, LLVM_ADD_VERSION, CLANG_ADD_VERSION, CLOSURE_COMPILER
   global NODE_JS, NODE_JS_TEST, V8_ENGINE, JS_ENGINES, SPIDERMONKEY_ENGINE, WASM_ENGINES
+  global WASM_BINDGEN
 
   # EM_CONFIG stuff
   if not JS_ENGINES:
@@ -75,6 +77,7 @@ def normalize_config_settings():
   JS_ENGINES = [listify(engine) for engine in JS_ENGINES]
   WASM_ENGINES = [listify(engine) for engine in WASM_ENGINES]
   CLOSURE_COMPILER = listify(CLOSURE_COMPILER)
+  WASM_BINDGEN = listify(WASM_BINDGEN)
   if not CACHE:
     CACHE = path_from_root('cache')
   if not PORTS:
@@ -124,6 +127,7 @@ def parse_config_file():
     'CACHE',
     'PORTS',
     'COMPILER_WRAPPER',
+    'WASM_BINDGEN',
   )
 
   # Only propagate certain settings from the config file.

tools/emscripten.py

@@ -578,10 +578,11 @@ def finalize_wasm(infile, outfile, js_syms):
   if not need_name_section:
     strip_sections += ['name']
 
-  if strip_sections or not settings.GENERATE_DWARF:
-    building.save_intermediate(outfile, 'strip.wasm')
-    building.strip(infile, outfile, debug=not settings.GENERATE_DWARF,
-                   sections=strip_sections)
+  # TODO(walkingeyerobot): make this work. it appears to not like the wasm file from wasm-bindgen
+  #if strip_sections or not settings.GENERATE_DWARF:
+  #  building.save_intermediate(outfile, 'strip.wasm')
+  #  building.strip(infile, outfile, debug=not settings.GENERATE_DWARF,
+  #                 sections=strip_sections)
 
   metadata = get_metadata(outfile, outfile, modify_wasm, args)
 
@@ -951,6 +952,7 @@ def install_wrapper(sym):
     else:
       wrapper += f"wasmExports['{name}']"
 
+    # TODO(walkingeyerobot): if the export is from rust, it should probably be excluded here and dealt with elsewhere.
     wrappers.append(wrapper)
   return wrappers
 

tools/link.py

@@ -38,6 +38,7 @@
 from .shared import in_temp, safe_copy, do_replace, OFormat
 from .shared import DEBUG, WINDOWS, DYNAMICLIB_ENDINGS, STATICLIB_ENDINGS
 from .shared import unsuffixed, unsuffixed_basename, get_file_suffix
+from .shared import get_emscripten_temp_dir
 from .settings import settings, default_setting, user_settings, JS_ONLY_SETTINGS, DEPRECATED_SETTINGS
 from .minimal_runtime_shell import generate_minimal_runtime_html
 
@@ -1932,6 +1933,11 @@ def phase_post_link(options, state, in_wasm, wasm_target, target, js_syms, base_
 
   settings.TARGET_JS_NAME = os.path.basename(state.js_target)
 
+  if settings.WASM_BINDGEN:
+    phase_wasm_bindgen(in_wasm)
+    settings.PRE_JS_FILES += [os.path.abspath(get_emscripten_temp_dir() + '/wbg_out/wbg_pre.js')]
+    settings.JS_LIBRARIES += [os.path.abspath(get_emscripten_temp_dir() + '/wbg_out/library_wbg.js')]
+
   metadata = phase_emscript(in_wasm, wasm_target, js_syms, base_metadata)
 
   if settings.EMBIND_AOT:
@@ -1950,6 +1956,10 @@ def phase_post_link(options, state, in_wasm, wasm_target, target, js_syms, base_
     phase_final_emitting(options, state, target, wasm_target)
 
 
+def phase_wasm_bindgen(in_wasm, wasm_target=None):
+  building.run_wasm_bindgen(in_wasm, wasm_target)
+
+
 @ToolchainProfiler.profile_block('emscript')
 def phase_emscript(in_wasm, wasm_target, js_syms, base_metadata):
   # Emscripten