Add a test for weak symbols

mach/dylib/weak.h

@@ -0,0 +1,8 @@
+template <class T>
+class C {
+ public:
+  static int weak;
+};
+
+template <class T>
+int C<T>::weak = 0;

mach/dylib/weak_lib.cc

@@ -0,0 +1,9 @@
+#include <stdio.h>
+
+#include "weak.h"
+
+__attribute__((constructor)) void init_weak() {
+  printf("init_weak before: %d %p\n", C<int>::weak, &C<int>::weak);
+  C<int>::weak = 42;
+  printf("init_weak after: %d %p\n", C<int>::weak, &C<int>::weak);
+}

mach/dylib/weak_main.cc

@@ -0,0 +1,24 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "weak.h"
+
+int main() {
+#ifdef DL
+  int dlflags = RTLD_NOW;
+# ifdef __APPLE__
+  void* h = dlopen("mach/dylib/weak_lib.dylib", dlflags);
+# else
+  void* h = dlopen("mach/dylib/weak_lib.so", dlflags);
+# endif
+  if (!h) {
+    printf("%s\n", dlerror());
+    abort();
+  }
+#endif
+  printf("%d %p\n", C<int>::weak, &C<int>::weak);
+  if (C<int>::weak != 42) {
+    abort();
+  }
+}

runtests.sh

@@ -74,6 +74,19 @@ apple gcc --sysroot=$MAC_TOOL_DIR -g mach/dylib/dlfcn.c -o mach/dylib/dlfcn
 echo "Running mach/dylib/dlfcn"
 mach/dylib/dlfcn
 
+echo "Running dylib tests with a weak symbol"
+
+apple g++ -g -fPIC -dynamiclib mach/dylib/weak_lib.cc -o mach/dylib/weak_lib.dylib
+apple g++ -g -fPIC mach/dylib/weak_main.cc -o mach/dylib/weak_main mach/dylib/weak_lib.dylib
+apple g++ -g -fPIC mach/dylib/weak_main.cc -o mach/dylib/weak_main-dl -DDL
+
+echo "Running mach/dylib/weak_main"
+mach/dylib/weak_main
+
+echo "Running mach/dylib/weak_main-dl"
+mach/dylib/weak_main-dl
+
+
 # Need this file from Xcode 4
 CLANG=$MAC_BIN_DIR/clang-137
 if [ -x $CLANG ]; then