warn/error on missing js library symbols, avoiding false positives by…

… telling compiler.js which methods were implemented in C emscripten-core#4077 emscripten-core#2154

emscripten.py

@@ -193,6 +193,8 @@ def fix_dot_zero(m):
 
     settings['MAX_GLOBAL_ALIGN'] = metadata['maxGlobalAlign']
 
+    settings['IMPLEMENTED_FUNCTIONS'] = metadata['implementedFunctions']
+
     assert not (metadata['simd'] and settings['SPLIT_MEMORY']), 'SIMD is used, but not supported in SPLIT_MEMORY'
 
     # Save settings to a file to work around v8 issue 1579

src/compiler.js

@@ -162,6 +162,7 @@ if (settings_file) {
 
 EXPORTED_FUNCTIONS = set(EXPORTED_FUNCTIONS);
 EXCEPTION_CATCHING_WHITELIST = set(EXCEPTION_CATCHING_WHITELIST);
+IMPLEMENTED_FUNCTIONS = set(IMPLEMENTED_FUNCTIONS);
 
 // TODO: Implement support for proper preprocessing, e.g. "#if A || B" and "#if defined(A) || defined(B)" to
 // avoid needing this here.

src/jsifier.js

@@ -118,7 +118,7 @@ function JSify(data, functionsOnly) {
       functionStubSigs[item.ident] = Functions.getSignature(item.returnType.text, item.params.map(function(arg) { return arg.type }), false);
     }
 
-    function addFromLibrary(ident, notDep) {
+    function addFromLibrary(ident) {
       if (ident in addedLibraryItems) return '';
       addedLibraryItems[ident] = true;
 
@@ -139,7 +139,7 @@ function JSify(data, functionsOnly) {
       var noExport = false;
 
       if ((!LibraryManager.library.hasOwnProperty(ident) && !LibraryManager.library.hasOwnProperty(ident + '__inline')) || SIDE_MODULE) {
-        if (notDep) {
+        if (!(finalName in IMPLEMENTED_FUNCTIONS)) {
           if (VERBOSE || ident.substr(0, 11) !== 'emscripten_') { // avoid warning on emscripten_* functions which are for internal usage anyhow
             if (!LINKABLE) {
               if (ERROR_ON_UNDEFINED_SYMBOLS) error('unresolved symbol: ' + ident);
@@ -260,7 +260,7 @@ function JSify(data, functionsOnly) {
           delete LibraryManager.library[shortident + '__deps'];
         }
       }
-      item.JS = addFromLibrary(shortident, true);
+      item.JS = addFromLibrary(shortident);
     }
   }
 

tests/test_other.py

@@ -5347,6 +5347,54 @@ def test_umask_0(self):
   def test_no_missing_symbols(self): # simple hello world should not show any missing symbols
     check_execute([PYTHON, EMCC, path_from_root('tests', 'hello_world.c'), '-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1'])
 
+    # main() is implemented in C, and even if requested from JS, we should not warn
+    open('library_foo.js', 'w').write('''
+mergeInto(LibraryManager.library, {
+  my_js__deps: ['main'],
+  my_js: (function() {
+      return function() {
+        console.log("hello " + _nonexistingvariable);
+      };
+  }()),
+});
+''')
+    open('test.cpp', 'w').write('''
+#include<stdio.h>
+#include<stdlib.h>
+
+extern "C" {
+  extern void my_js();
+}
+
+int main() {
+  my_js();
+  return EXIT_SUCCESS;
+}
+''')
+    check_execute([PYTHON, EMCC, 'test.cpp', '-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1', '--js-library', 'library_foo.js'])
+
+    # but we do error on a missing js var
+    open('library_foo.js', 'w').write('''
+mergeInto(LibraryManager.library, {
+  my_js__deps: ['main', 'nonexistingvariable'],
+  my_js: (function() {
+      return function() {
+        console.log("hello " + _nonexistingvariable);
+      };
+  }()),
+});
+''')
+    proc = Popen([PYTHON, EMCC, 'test.cpp', '-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1', '--js-library', 'library_foo.js'], stderr=PIPE)
+    out, err = proc.communicate()
+    assert proc.returncode != 0
+    assert 'unresolved symbol' in err
+
+    # and also for missing C code, of course (without the --js-library, it's just a missing C method)
+    proc = Popen([PYTHON, EMCC, 'test.cpp', '-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1'], stderr=PIPE)
+    out, err = proc.communicate()
+    assert proc.returncode != 0
+    assert 'unresolved symbol' in err
+
   def test_realpath(self):
     open('src.c', 'w').write(r'''
 #include <stdlib.h>