Open Radar

 
Summary:

building the following C++ snippet fails when building with 10.8sdk, with llvm-g++-4.2 and targeting 10.4

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

int main()
{
  stringstream ss;
  string s("hello world");

  ss << s;

  cout << ss.str() << endl;
  return 0;
}

Steps to Reproduce:

llvm-g++-4.2 -arch i386 -mmacosx-version-min=10.4 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk main.cpp

Expected Results:

The snippet should compile without errors.
Actual Results:

error: explicit instantiation of ‘std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]’ but no definition available

Regression:

Notes:

I tracked the problem down to /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/basic_string.h line 2411

  template<typename _CharT, typename _Traits, typename _Alloc>
    inline basic_ostream<_CharT, _Traits>&
    operator<<(basic_ostream<_CharT, _Traits>& __os,
	       const basic_string<_CharT, _Traits, _Alloc>& __str)
#if __TARGETING_4_0_DYLIB
    ; // __ostream_insert() not exported from libstdc++.6.0.4 dylib
#else
    {
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 586. string inserter not a formatted function
      return __ostream_insert(__os, __str.data(), __str.size());
    }
#endif

As you can see, the template operator has no definition when __TARGETING_4_0_DYLIB is non 0.
__TARGETING_4_0_DYLIB is defined in /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/usr/include/c++/4.2.1/bits/os_defines.h line 111

#if __IPHONE_OS_VERSION_MIN_REQUIRED
	#define __TARGETING_4_0_DYLIB  0
#else 
	#define __TARGETING_4_0_DYLIB (__MAC_OS_X_VERSION_MIN_REQUIRED < 1060)
#endif

Since I'm targeting 10.4 (our customers require Tiger support), __TARGETING_4_0_DYLIB gets defined to 1 preventing operator definition in bits/basic_string.h