Build-time error on use of emscripten_promise_any if Promise.any is not available

Author: sbc100

emcc.py

@@ -2432,7 +2432,10 @@ def phase_linker_setup(options, state, newargs):
       settings.WASM_WORKER_FILE = unsuffixed(os.path.basename(target)) + '.ww.js'
     settings.JS_LIBRARIES.append((0, shared.path_from_root('src', 'library_wasm_worker.js')))
 
+  # TODO(sbc): Find make a generic way to expose the feature matrix to JS
+  # compiler rather then adding them all ad-hoc as internal settings
   settings.SUPPORTS_GLOBALTHIS = feature_matrix.caniuse(feature_matrix.Feature.GLOBALTHIS)
+  settings.SUPPORTS_PROMISE_ANY = feature_matrix.caniuse(feature_matrix.Feature.PROMISE_ANY)
   if not settings.BULK_MEMORY:
     settings.BULK_MEMORY = feature_matrix.caniuse(feature_matrix.Feature.BULK_MEMORY)
 

src/library_promise.js

@@ -216,7 +216,15 @@ mergeInto(LibraryManager.library, {
     return id;
   },
 
-  emscripten_promise_any__deps: ['$promiseMap', '$idsToPromises'],
+
+  emscripten_promise_any__deps: [
+    '$promiseMap', '$idsToPromises',
+#if !SUPPORTS_PROMISE_ANY
+    // Adding a function here as a dependency will trigger it to be run
+    // at build time, if and only if this function gets included.
+    () => error("emscripten_promise_any used, but Promise.any is not supported the current browser configuration"),
+#endif
+  ],
   emscripten_promise_any: function(idBuf, errorBuf, size) {
     var promises = idsToPromises(idBuf, size);
 #if RUNTIME_DEBUG

src/settings_internal.js

@@ -175,6 +175,9 @@ var TARGET_NOT_SUPPORTED = 0x7FFFFFFF;
 // Used to track whether target environment supports the 'globalThis' attribute.
 var SUPPORTS_GLOBALTHIS = false;
 
+// Used to track whether target environment supports the 'Promise.any'.
+var SUPPORTS_PROMISE_ANY = false;
+
 // Wasm backend symbols that are considered system symbols and don't
 // have the normal C symbol name mangled applied (== prefix with an underscore)
 // (Also implicily on this list is any function that starts with string "dynCall_")

test/test_core.py

@@ -9761,6 +9761,14 @@ def test_main_reads_args(self):
 
   @requires_node
   def test_promise(self):
+    # This test depends on Promise.any, which in turn requires a modern target.  Check that it
+    # fails to even build without bumping the min versions:
+    err = self.expect_fail([EMCC, test_file('core/test_promise.c')])
+    self.assertContained('error: emscripten_promise_any used, but Promise.any is not supported the current browser configuration', err)
+    self.set_setting('MIN_NODE_VERSION', '150000')
+    self.set_setting('MIN_SAFARI_VERSION', '150000')
+    self.set_setting('MIN_FIREFOX_VERSION', '79')
+    self.set_setting('MIN_CHROME_VERSION', '85')
     self.do_core_test('test_promise.c')
 
 

tools/feature_matrix.py

@@ -15,13 +15,17 @@
 
 
 class Feature(IntEnum):
+  # Wasm features
   NON_TRAPPING_FPTOINT = auto()
   SIGN_EXT = auto()
   BULK_MEMORY = auto()
   MUTABLE_GLOBALS = auto()
-  JS_BIGINT_INTEGRATION = auto()
   THREADS = auto()
+
+  # JS Features
+  JS_BIGINT_INTEGRATION = auto()
   GLOBALTHIS = auto()
+  PROMISE_ANY = auto()
 
 
 default_features = {Feature.SIGN_EXT, Feature.MUTABLE_GLOBALS}
@@ -62,25 +66,44 @@ class Feature(IntEnum):
     'edge': 79,
     'firefox': 65,
     'safari': 120100,
-    # 'node': 120000
+    'node': 120000,
+  },
+  Feature.PROMISE_ANY: {
+    'chrome': 85,
+    'firefox': 79,
+    'safari': 140000,
+    'node': 150000,
   },
 }
 
 
 def caniuse(feature):
   min_versions = min_browser_versions[feature]
+
+  def report_missing(setting_name):
+    setting_value = getattr(settings, setting_name)
+    logger.debug(f'cannot use {feature.name} because {setting_name} is too old: {setting_value}')
+
   if settings.MIN_CHROME_VERSION < min_versions['chrome']:
+    report_missing('MIN_CHROME_VERSION')
     return False
   # For edge we just use the same version requirements as chrome since,
   # at least for modern versions of edge, they share version numbers.
   if settings.MIN_EDGE_VERSION < min_versions['chrome']:
+    report_missing('MIN_EDGE_VERSION')
     return False
   if settings.MIN_FIREFOX_VERSION < min_versions['firefox']:
+    report_missing('MIN_FIREFOX_VERSION')
     return False
   if settings.MIN_SAFARI_VERSION < min_versions['safari']:
+    report_missing('MIN_SAFARI_VERSION')
     return False
   # IE don't support any non-MVP features
   if settings.MIN_IE_VERSION != 0x7FFFFFFF:
+    report_missing('MIN_IE_VERSION')
+    return False
+  if 'node' in min_versions and settings.MIN_NODE_VERSION < min_versions['node']:
+    report_missing('MIN_NODE_VERSION')
     return False
   return True