Don't allow EXPORTED_FUNCTIONS with MAIN_MODULE=1/SIDE_MODULE=1

This doesn't make sense since these imply all functionm are to be
exported.

Author: sbc100

emcc.py

@@ -1158,17 +1158,23 @@ def check(input_file):
       options.memory_init_file = False # memory init file is not supported with asm.js side modules, must be executable synchronously (for dlopen)
 
     if shared.Settings.MAIN_MODULE or shared.Settings.SIDE_MODULE:
-      assert shared.Settings.ASM_JS, 'module linking requires asm.js output (-s ASM_JS=1)'
+      if not shared.Settings.ASM_JS:
+        exit_with_error('module linking requires asm.js output (-s ASM_JS=1)')
       if shared.Settings.MAIN_MODULE != 2 and shared.Settings.SIDE_MODULE != 2:
         shared.Settings.LINKABLE = 1
       shared.Settings.RELOCATABLE = 1
-      assert not options.use_closure_compiler, 'cannot use closure compiler on shared modules'
+      if options.use_closure_compiler:
+        exit_with_error('cannot use closure compiler on shared modules')
       # shared modules need memory utilities to allocate their memory
       shared.Settings.EXPORTED_RUNTIME_METHODS += [
         'allocate',
         'getMemory',
       ]
 
+    if shared.Settings.LINKABLE and shared.Settings.USER_EXPORTED_FUNCTIONS:
+      exit_with_error('EXPORTED_FUNCTIONS is not valid with LINKABLE set (normally due to SIDE_MODULE=1/MAIN_MODULE=1) '
+                      'since all functions are exported.  To export only a subset use SIDE_MODULE=2/MAIN_MODULE=2')
+
     if shared.Settings.RELOCATABLE:
       shared.Settings.ALLOW_TABLE_GROWTH = 1
 

tests/test_other.py

@@ -6364,91 +6364,91 @@ def test(args, expected):
       test(['-O' + str(opts), '-s', 'MAIN_MODULE=1', '-s', 'EMULATED_FUNCTION_POINTERS=2'], unchanged)
       test(['-O' + str(opts), '-s', 'MAIN_MODULE=1', '-s', 'EMULATED_FUNCTION_POINTERS=1'], flipped) # but you can disable that
 
-  def test_minimal_dynamic(self):
-    def run(wasm):
-      print('wasm?', wasm)
-      library_file = 'library.wasm' if wasm else 'library.js'
+  @parameterized({
+    'wasm': [True],
+    'asmjs': [False],
+  })
+  def test_minimal_dynamic(self, wasm):
+    if self.is_wasm_backend() and not wasm:
+      self.skipTest("asmjs only")
+    library_file = 'library.wasm' if wasm else 'library.js'
 
-      def test(main_args, library_args=[], expected='hello from main\nhello from library'):
-        print('testing', main_args, library_args)
-        self.clear()
-        create_test_file('library.c', r'''
-          #include <stdio.h>
-          void library_func() {
-          #ifdef USE_PRINTF
-            printf("hello from library: %p\n", &library_func);
-          #else
-            puts("hello from library");
-          #endif
-          }
-        ''')
-        # -fno-builtin to prevent printf -> iprintf optimization
-        run_process([PYTHON, EMCC, 'library.c', '-fno-builtin', '-s', 'SIDE_MODULE=1', '-O2', '-o', library_file, '-s', 'WASM=' + str(wasm), '-s', 'EXPORT_ALL'] + library_args)
-        create_test_file('main.c', r'''
-          #include <dlfcn.h>
-          #include <stdio.h>
-          int main() {
-            puts("hello from main");
-            void *lib_handle = dlopen("%s", 0);
-            if (!lib_handle) {
-              puts("cannot load side module");
-              return 1;
-            }
-            typedef void (*voidfunc)();
-            voidfunc x = (voidfunc)dlsym(lib_handle, "library_func");
-            if (!x) puts("cannot find side function");
-            else x();
+    def test(main_args, library_args=[], expected='hello from main\nhello from library'):
+      print('testing', main_args, library_args)
+      self.clear()
+      create_test_file('library.c', r'''
+        #include <stdio.h>
+        void library_func() {
+        #ifdef USE_PRINTF
+          printf("hello from library: %p\n", &library_func);
+        #else
+          puts("hello from library");
+        #endif
+        }
+      ''')
+      # -fno-builtin to prevent printf -> iprintf optimization
+      run_process([PYTHON, EMCC, 'library.c', '-fno-builtin', '-s', 'SIDE_MODULE=1', '-O2', '-o', library_file, '-s', 'WASM=' + str(wasm), '-s', 'EXPORT_ALL'] + library_args)
+      create_test_file('main.c', r'''
+        #include <dlfcn.h>
+        #include <stdio.h>
+        int main() {
+          puts("hello from main");
+          void *lib_handle = dlopen("%s", 0);
+          if (!lib_handle) {
+            puts("cannot load side module");
+            return 1;
           }
-        ''' % library_file)
-        run_process([PYTHON, EMCC, 'main.c', '--embed-file', library_file, '-O2', '-s', 'WASM=' + str(wasm)] + main_args)
-        self.assertContained(expected, run_js('a.out.js', assert_returncode=None, stderr=STDOUT))
-        size = os.path.getsize('a.out.js')
-        if wasm:
-          size += os.path.getsize('a.out.wasm')
-        side_size = os.path.getsize(library_file)
-        print('  sizes:', size, side_size)
-        return (size, side_size)
-
-      def percent_diff(x, y):
-        small = min(x, y)
-        large = max(x, y)
-        return float(100 * large) / small - 100
+          typedef void (*voidfunc)();
+          voidfunc x = (voidfunc)dlsym(lib_handle, "library_func");
+          if (!x) puts("cannot find side function");
+          else x();
+        }
+      ''' % library_file)
+      run_process([PYTHON, EMCC, 'main.c', '--embed-file', library_file, '-O2', '-s', 'WASM=' + str(wasm)] + main_args)
+      self.assertContained(expected, run_js('a.out.js', assert_returncode=None, stderr=STDOUT))
+      size = os.path.getsize('a.out.js')
+      if wasm:
+        size += os.path.getsize('a.out.wasm')
+      side_size = os.path.getsize(library_file)
+      print('  sizes:', size, side_size)
+      return (size, side_size)
 
-      full = test(main_args=['-s', 'MAIN_MODULE=1'])
-      # printf is not used in main, but libc was linked in, so it's there
-      printf = test(main_args=['-s', 'MAIN_MODULE=1'], library_args=['-DUSE_PRINTF'])
+    def percent_diff(x, y):
+      small = min(x, y)
+      large = max(x, y)
+      return float(100 * large) / small - 100
 
-      # main module tests
+    full = test(main_args=['-s', 'MAIN_MODULE=1'])
+    # printf is not used in main, but libc was linked in, so it's there
+    printf = test(main_args=['-s', 'MAIN_MODULE=1'], library_args=['-DUSE_PRINTF'])
 
-      # dce in main, and it fails since puts is not exported
-      dce = test(main_args=['-s', 'MAIN_MODULE=2'], expected=('cannot', 'undefined'))
+    # main module tests
 
-      # with exporting, it works
-      dce = test(main_args=['-s', 'MAIN_MODULE=2', '-s', 'EXPORTED_FUNCTIONS=["_main", "_puts"]'])
+    # dce in main, and it fails since puts is not exported
+    dce = test(main_args=['-s', 'MAIN_MODULE=2'], expected=('cannot', 'undefined'))
 
-      # printf is not used in main, and we dce, so we failz
-      dce_fail = test(main_args=['-s', 'MAIN_MODULE=2'], library_args=['-DUSE_PRINTF'], expected=('cannot', 'undefined'))
+    # with exporting, it works
+    dce = test(main_args=['-s', 'MAIN_MODULE=2', '-s', 'EXPORTED_FUNCTIONS=["_main", "_puts"]'])
 
-      # exporting printf in main keeps it alive for the library
-      dce_save = test(main_args=['-s', 'MAIN_MODULE=2', '-s', 'EXPORTED_FUNCTIONS=["_main", "_printf", "_puts"]'], library_args=['-DUSE_PRINTF'])
+    # printf is not used in main, and we dce, so we failz
+    dce_fail = test(main_args=['-s', 'MAIN_MODULE=2'], library_args=['-DUSE_PRINTF'], expected=('cannot', 'undefined'))
 
-      self.assertLess(percent_diff(full[0], printf[0]), 4)
-      self.assertLess(percent_diff(dce[0], dce_fail[0]), 4)
-      self.assertLess(dce[0], 0.2 * full[0]) # big effect, 80%+ is gone
-      self.assertGreater(dce_save[0], 1.05 * dce[0]) # save exported all of printf
+    # exporting printf in main keeps it alive for the library
+    dce_save = test(main_args=['-s', 'MAIN_MODULE=2', '-s', 'EXPORTED_FUNCTIONS=["_main", "_printf", "_puts"]'], library_args=['-DUSE_PRINTF'])
 
-      # side module tests
+    self.assertLess(percent_diff(full[0], printf[0]), 4)
+    self.assertLess(percent_diff(dce[0], dce_fail[0]), 4)
+    self.assertLess(dce[0], 0.2 * full[0]) # big effect, 80%+ is gone
+    self.assertGreater(dce_save[0], 1.05 * dce[0]) # save exported all of printf
 
-      # mode 2, so dce in side, but library_func is not exported, so it is dce'd
-      side_dce_fail = test(main_args=['-s', 'MAIN_MODULE=1'], library_args=['-s', 'SIDE_MODULE=2'], expected='cannot find side function')
-      # mode 2, so dce in side, and library_func is not exported
-      side_dce_work = test(main_args=['-s', 'MAIN_MODULE=1'], library_args=['-s', 'SIDE_MODULE=2', '-s', 'EXPORTED_FUNCTIONS=["_library_func"]'], expected='hello from library')
+    # side module tests
 
-      self.assertLess(side_dce_fail[1], 0.95 * side_dce_work[1]) # removing that function saves a chunk
+    # mode 2, so dce in side, but library_func is not exported, so it is dce'd
+    side_dce_fail = test(main_args=['-s', 'MAIN_MODULE=1'], library_args=['-s', 'SIDE_MODULE=2'], expected='cannot find side function')
+    # mode 2, so dce in side, and library_func is not exported
+    side_dce_work = test(main_args=['-s', 'MAIN_MODULE=1'], library_args=['-s', 'SIDE_MODULE=2', '-s', 'EXPORTED_FUNCTIONS=["_library_func"]'], expected='hello from library')
 
-    run(wasm=1)
-    if not self.is_wasm_backend():
-      run(wasm=0)
+    self.assertLess(side_dce_fail[1], 0.95 * side_dce_work[1]) # removing that function saves a chunk
 
   def test_ld_library_path(self):
     create_test_file('hello1.c', r'''

tools/shared.py

@@ -1909,15 +1909,15 @@ def link_lld(args, target, opts=[], lto_level=0):
 
     if Settings.LINKABLE:
       cmd.append('--export-all')
+    else:
+      # in standalone mode, crt1 will call the constructors from inside the wasm
+      if not Settings.STANDALONE_WASM:
+        cmd += ['--export', '__wasm_call_ctors']
 
-    # in standalone mode, crt1 will call the constructors from inside the wasm
-    if not Settings.STANDALONE_WASM:
-      cmd += ['--export', '__wasm_call_ctors']
-
-    cmd += ['--export', '__data_end']
+      cmd += ['--export', '__data_end']
 
-    for export in Settings.EXPORTED_FUNCTIONS:
-      cmd += ['--export', export[1:]] # Strip the leading underscore
+      for export in Settings.EXPORTED_FUNCTIONS:
+        cmd += ['--export', export[1:]] # Strip the leading underscore
 
     if Settings.RELOCATABLE:
       if Settings.SIDE_MODULE: