Backport fix for: Reverse deps with -sERROR_ON_UNDEFINED_SYMBOLS=0

emcc.py

@@ -541,7 +541,7 @@ def build_symbol_list(filename):
     """
     library_syms = generate_js_sym_info()
 
-    write_file(filename, json.dumps(library_syms, separators=(',', ':')))
+    write_file(filename, json.dumps(library_syms, separators=(',', ':'), indent=2))
 
   # We need to use a separate lock here for symbol lists because, unlike with system libraries,
   # it's normally for these file to get pruned as part of normal operation.  This means that it

test/test_other.py

@@ -5198,15 +5198,17 @@ def test_bad_lookup(self):
     'full_only': [{'EMCC_FORCE_STDLIBS': 'libc,libc++abi,libc++,libmalloc', 'EMCC_ONLY_FORCED_STDLIBS': '1'}, False],
   })
   def test_only_force_stdlibs(self, env, fail):
+    cmd = [EMXX, test_file('hello_libcxx.cpp')]
     with env_modify(env):
-      err = self.run_process([EMXX, test_file('hello_libcxx.cpp'), '-sWARN_ON_UNDEFINED_SYMBOLS=0'], stderr=PIPE).stderr
-      if 'EMCC_ONLY_FORCED_STDLIBS' in env:
-        self.assertContained('EMCC_ONLY_FORCED_STDLIBS is deprecated', err)
       if fail:
-        output = self.run_js('a.out.js', assert_returncode=NON_ZERO)
-        self.assertContained('missing function', output)
+        err = self.expect_fail(cmd)
+        self.assertContained('undefined symbol: malloc', err)
       else:
-        self.assertContained('hello, world!', self.run_js('a.out.js'))
+        err = self.run_process(cmd, stderr=PIPE).stderr
+        if 'EMCC_ONLY_FORCED_STDLIBS' in env:
+          self.assertContained('EMCC_ONLY_FORCED_STDLIBS is deprecated', err)
+        else:
+          self.assertContained('hello, world!', self.run_js('a.out.js'))
 
   def test_only_force_stdlibs_2(self):
     create_file('src.cpp', r'''
@@ -12049,6 +12051,22 @@ def test_main_module_no_undefined(self):
     # Test that ERROR_ON_UNDEFINED_SYMBOLS works with MAIN_MODULE.
     self.do_runf(test_file('hello_world.c'), emcc_args=['-sMAIN_MODULE', '-sERROR_ON_UNDEFINED_SYMBOLS'])
 
+  def test_reverse_deps_allow_undefined(self):
+    # Check that reverse deps are still included even when -sERROR_ON_UNDEFINED_SYMBOLS=0.
+    create_file('test.c', '''
+    #include <assert.h>
+    #include <stdio.h>
+    #include <netdb.h>
+
+    int main() {
+      // Reference in getaddrinfo which has reverse deps on malloc and htons
+      // We expect these to be exported even when -sERROR_ON_UNDEFINED_SYMBOLS=0.
+      printf("%p\\n", &getaddrinfo);
+      return 0;
+    }
+    ''')
+    self.do_runf('test.c', emcc_args=['-sERROR_ON_UNDEFINED_SYMBOLS=0'])
+
   @parameterized({
     'relocatable': ('-sRELOCATABLE',),
     'linkable': ('-sLINKABLE',),

tools/building.py

@@ -135,10 +135,7 @@ def create_stub_object(external_symbols):
   stubfile = shared.get_temp_files().get('libemscripten_js_symbols.so').name
   stubs = ['#STUB']
   for name, deps in external_symbols.items():
-    if settings.ERROR_ON_UNDEFINED_SYMBOLS:
-      stubs.append('%s: %s' % (name, ','.join(deps)))
-    else:
-      stubs.append(name)
+    stubs.append('%s: %s' % (name, ','.join(deps)))
   utils.write_file(stubfile, '\n'.join(stubs))
   return stubfile