Qt OS 10.6 build not running on OS 10.5 and less

This issue has been queried twice before by separate people, but there have been no answers.

So, I'm posting, again:

Building Qt4.7 on 10.6.6, XCode 3.2.5, g++-4.2 with the flag '-mmacosx-version-min=10.4', which I'm presuming is taking care of the dirty work, underneath.

When I bring it over to 10.5, it crashes right out of the box with this:

<... process identification info removed ...>

Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Crashed Thread:  0

Dyld Error Message:
  Symbol not found: __ZSt16__ostream_insertIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_PKS3_i
  Referenced from: /Applications/MyApp.app/Contents/MacOS/MyApp
  Expected in开发者_高级运维: /usr/lib/libstdc++.6.dylib

Has anyone come to a resolution on this?

---

You need to specify -sdk /Developer/SDKs/MacOSX10.4u.sdk in your configure line when building Qt itself. The minimum version option is just to trigger some pre-processor macros to limit APIs to 10.4 level.

Note this may stop you from building 64-bit binaries. But I am not sure.