Make embind work with -fvisibility=hidden

system/include/emscripten/val.h

@@ -23,6 +23,7 @@
 #include <variant>
 #endif
 
+#define EMSCRIPTEN_EXPORT __attribute__((visibility("default")))
 
 namespace emscripten {
 
@@ -284,7 +285,7 @@ struct WireTypePack {
 static const char name##_symbol[] = #name;                          \
 static const ::emscripten::internal::symbol_registrar<name##_symbol> name##_registrar
 
-class val {
+class EMSCRIPTEN_EXPORT val {
 public:
   // missing operators:
   // * ~ - + ++ --

system/include/emscripten/wire.h

@@ -24,6 +24,7 @@
 #include <string>
 
 #define EMSCRIPTEN_ALWAYS_INLINE __attribute__((always_inline))
+#define EMSCRIPTEN_EXPORT __attribute__((visibility("default")))
 
 #ifndef EMSCRIPTEN_HAS_UNBOUND_TYPE_NAMES
 #define EMSCRIPTEN_HAS_UNBOUND_TYPE_NAMES 1
@@ -430,7 +431,7 @@ constexpr bool typeSupportsMemoryView() {
 } // namespace internal
 
 template<typename ElementType>
-struct memory_view {
+struct EMSCRIPTEN_EXPORT memory_view {
     memory_view() = delete;
     explicit memory_view(size_t size, const ElementType* data)
         : size(size)

test/test_other.py

@@ -210,6 +210,17 @@ def decorated(self, *args, **kwargs):
   return decorated
 
 
+def requires_dylink(func):
+  assert callable(func)
+
+  @wraps(func)
+  def decorated(self, *args, **kwargs):
+    self.check_dylink()
+    return func(self, *args, **kwargs)
+
+  return decorated
+
+
 def llvm_nm(file):
   output = shared.run_process([LLVM_NM, file], stdout=PIPE).stdout
 
@@ -3346,6 +3357,54 @@ def test_embind_jsgen_method_pointer_stability(self):
     # AOT JS generation still works correctly.
     self.do_runf('other/embind_jsgen_method_pointer_stability.cpp', 'done')
 
+  def build_dylink_lib(self, filename, outfile='liblib.so', emcc_args=None):
+    self.clear_setting('MAIN_MODULE')
+    self.set_setting('SIDE_MODULE')
+    cmd = [compiler_for(filename), filename, '-o', outfile] + self.get_emcc_args()
+    if emcc_args:
+      cmd += emcc_args
+    self.run_process(cmd)
+
+  def prep_dylink_main(self):
+    self.clear_setting('SIDE_MODULE')
+    self.set_setting('MAIN_MODULE', 1)
+
+  @requires_dylink
+  def test_embind_dylink_visibility_hidden(self):
+    # Check that embind is usable from a library built with "-fvisibility=hidden"
+    create_file('liba.cpp', r'''
+      #include <emscripten/val.h>
+
+      #define EXPORT __attribute__((visibility("default")))
+      using namespace emscripten;
+
+      EXPORT void liba_fun() {
+        unsigned char buffer[1];
+        val view(typed_memory_view(1, buffer));
+      }
+    ''')
+
+    self.build_dylink_lib('liba.cpp', outfile='liba.so', emcc_args=['-std=c++11', '-fvisibility=hidden'])
+    self.prep_dylink_main()
+    self.emcc_args = ['liba.so', '-L.', '--bind']
+    create_file('main.cpp', r'''
+      #include <stdio.h>
+      #include <emscripten/val.h>
+
+      using namespace emscripten;
+
+      void liba_fun();
+
+      int main() {
+
+        liba_fun();
+
+        printf("done\n");
+        return 0;
+      }
+    ''')
+    self.do_runf('main.cpp', 'done\n')
+
   def test_emit_tsd(self):
     self.run_process([EMCC, test_file('other/test_emit_tsd.c'),
                       '--emit-tsd', 'test_emit_tsd.d.ts', '-sEXPORT_ES6',