Two changes: 1) I still didn't have the ABI correct to match the gcc-4.2 std::string under the exception classes. I think the changes to stdexcept.cpp have got that down now. 2) On Apple platforms I'm seeing visibility bugs in applications with respect to type_info's being hidden. This is causing dynamic_cast to malfunction because there are multiple type_info's running around for one type within an application, making dynamic_cast believe that one type is actually multiple types. As a stop gap measure I'm trying to detect this error, print out an error message, but continue with the most likely desired result. This is all under __APPLE__. This behavior can be expanded to other platforms if desired.

llvm-svn: 164809

libcxxabi/src/private_typeinfo.cpp

@@ -9,6 +9,10 @@
 
 #include "private_typeinfo.h"
 
+#if __APPLE__
+#include <sys/syslog.h>
+#endif
+
 namespace __cxxabiv1
 {
 
@@ -437,6 +441,19 @@ __dynamic_cast(const void* static_ptr,
         info.number_of_dst_type = 1;
         // Do the  search
         dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path);
+#if __APPLE__
+        // The following if should always be false because we should definitely
+        //   find (static_ptr, static_type), either on a public or private path
+        if (info.path_dst_ptr_to_static_ptr == unknown)
+        {
+            // We get here only if there is some kind of visibility problem
+            //   in client code.
+            syslog(LOG_ERR, "dynamic_cast error 1: There is a hidden visibility "
+                    "problem associated with the type_info's of %s" 
+                    " and/or %s.\n", static_type->name(), dynamic_type->name());
+            info.path_dst_ptr_to_static_ptr = public_path;
+        }
+#endif  // __APPLE__
         // Query the search.
         if (info.path_dst_ptr_to_static_ptr == public_path)
             dst_ptr = dynamic_ptr;
@@ -445,6 +462,18 @@ __dynamic_cast(const void* static_ptr,
     {
         // Not using giant short cut.  Do the search
         dynamic_type->search_below_dst(&info, dynamic_ptr, public_path);
+ #if __APPLE__
+        // The following if should always be false because we should definitely
+        //   find (static_ptr, static_type), either on a public or private path
+       if (info.path_dst_ptr_to_static_ptr == unknown &&
+            info.path_dynamic_ptr_to_static_ptr == unknown)
+        {
+            syslog(LOG_ERR, "dynamic_cast error 2: There is a hidden visibility "
+                    "problem associated with the type_info's of %s" 
+                    " and/or %s and/or %s.\n", static_type->name(), dynamic_type->name(),
+                    dst_type->name());
+        }
+#endif  // __APPLE__
         // Query the search.
         switch (info.number_to_static_ptr)
         {

libcxxabi/src/stdexcept.cpp

@@ -31,13 +31,18 @@ class __libcpp_nmstr
 private:
     const char* str_;
 
-    typedef std::size_t unused_t;
-    typedef std::ptrdiff_t count_t;
+    typedef int count_t;
 
-    static const std::ptrdiff_t offset = static_cast<std::ptrdiff_t>(2*sizeof(unused_t) +
-                                                                       sizeof(count_t));
+    struct _Rep_base
+    {
+        std::size_t len;
+        std::size_t cap;
+        count_t     count;
+    };
 
-    count_t& count() const _NOEXCEPT {return (count_t&)(*(str_ - sizeof(count_t)));}
+    static const std::ptrdiff_t offset = static_cast<std::ptrdiff_t>(sizeof(_Rep_base));
+
+    count_t& count() const _NOEXCEPT {return ((_Rep_base*)(str_ - offset))->count;}
 
 #if __APPLE__
     static
@@ -70,9 +75,9 @@ public:
 __libcpp_nmstr::__libcpp_nmstr(const char* msg)
 {
     std::size_t len = strlen(msg);
-    str_ = new char[len + 1 + offset];
-    unused_t* c = (unused_t*)str_;
-    c[0] = c[1] = len;
+    str_ = static_cast<const char*>(::operator new(len + 1 + offset));
+    _Rep_base* c = (_Rep_base*)str_;
+    c->len = c->cap = len;
     str_ += offset;
     count() = 0;
     std::strcpy(const_cast<char*>(c_str()), msg);
@@ -101,7 +106,9 @@ __libcpp_nmstr::operator=(const __libcpp_nmstr& s)
     if (p != get_gcc_empty_string_storage())
 #endif
         if (__sync_add_and_fetch((count_t*)(p-sizeof(count_t)), count_t(-1)) < 0)
-            delete [] (p-offset);
+        {
+            ::operator delete(const_cast<char*>(p-offset));
+        }
     return *this;
 }
 
@@ -112,7 +119,9 @@ __libcpp_nmstr::~__libcpp_nmstr()
     if (str_ != get_gcc_empty_string_storage())
 #endif
         if (__sync_add_and_fetch(&count(), count_t(-1)) < 0)
-            delete [] (str_ - offset);
+        {
+            ::operator delete(const_cast<char*>(str_ - offset));
+        }
 }
 
 }