do not export getValue and setValue by default. add a mechanism in ASSERTIONS that emits stubs that give an error message, so if a user depended on those being exported, in ASSERTIONS they get a clear error message

Author: kripken

src/modules.js

@@ -272,11 +272,17 @@ EXPORTED_RUNTIME_METHODS = unset(EXPORTED_RUNTIME_METHODS_SET);
 EXTRA_EXPORTED_RUNTIME_METHODS = [];
 
 function maybeExport(name) {
+  // if requested to be exported, export it
   if (name in EXPORTED_RUNTIME_METHODS_SET) {
     return 'Module["' + name + '"] = ' + name + ';';
-  } else {
-    return '';
   }
+  // do not export it. but if ASSERTIONS, emit a
+  // stub with an error, so the user gets a message
+  // if it is used, that they should export it
+  if (ASSERTIONS) {
+    return 'Module["' + name + '"] = function() { abort("\'' + name + '\' was not exported. add it to EXTRA_EXPORTED_RUNTIME_METHODS.") };';
+  }
+  return '';
 }
 
 var PassManager = {

src/preamble.js

@@ -805,7 +805,7 @@ function demangle(func) {
       stringToUTF8(s, buf, len);
       var status = _malloc(4);
       var ret = __cxa_demangle_func(buf, 0, 0, status);
-      if (getValue(status, 'i32') === 0 && ret) {
+      if ({{{ makeGetValue('status', '0', 'i32') }}} === 0 && ret) {
         return Pointer_stringify(ret);
       }
       // otherwise, libcxxabi failed

src/settings.js

@@ -353,8 +353,6 @@ var EXPORTED_RUNTIME_METHODS = [ // Runtime elements that are exported on Module
   'Runtime',
   'ccall',
   'cwrap',
-  'setValue',
-  'getValue',
   'ALLOC_NORMAL',
   'ALLOC_STACK',
   'ALLOC_STATIC',

tests/core/getValue_setValue.cpp

@@ -0,0 +1,9 @@
+#include<emscripten.h>
+
+int main() {
+  EM_ASM({
+    Module['setValue'](8, 1234, 'i32');
+    Module['print']('|' + Module['getValue'](8, 'i32') + '|');
+  });
+}
+

tests/core/getValue_setValue.txt

@@ -0,0 +1 @@
+|1234|

tests/core/getValue_setValue_assert.txt

@@ -0,0 +1 @@
+'setValue' was not exported. add it to EXTRA_EXPORTED_RUNTIME_METHODS.

tests/test_core.py

@@ -5936,6 +5936,20 @@ def process(filename):
       self.emcc_args += ['--closure', '1']
       self.do_run_in_out_file_test('tests', 'core', 'test_ccall', post_build=post)
 
+  def test_getValue_setValue(self):
+    # these used to be exported, but no longer are by default
+    def test(output_prefix=''):
+      self.do_run(open(path_from_root('tests', 'core', 'getValue_setValue.cpp')).read(),
+                  open(path_from_root('tests', 'core', 'getValue_setValue' + output_prefix + '.txt')).read())
+    # see that with assertions, we get a nice error message
+    Settings.EXTRA_EXPORTED_RUNTIME_METHODS = []
+    Settings.ASSERTIONS = 1
+    test('_assert')
+    Settings.ASSERTIONS = 0
+    # see that when we export them, things work
+    Settings.EXTRA_EXPORTED_RUNTIME_METHODS = ['getValue', 'setValue']
+    test()
+
   @no_wasm_backend('DEAD_FUNCTIONS elimination is done by the JSOptimizer')
   def test_dead_functions(self):
     src = r'''