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Re: Standard Library linking problems
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Re: Standard Library linking problems


  • Subject: Re: Standard Library linking problems
  • From: David Cohn <email@hidden>
  • Date: Thu, 24 Aug 2006 17:59:35 -0700

Hey all,

Sorry to hog bandwidth, but just for closure's sake...
That last error was due to a hard-coded LIBRARY_SEARCH_PATHS entry to the SDKs (set at the Target level, so I didn't see it at the Group level).


Thanks for all your patience!
--Dave



On Aug 24, 2006, at 11:25 AM, David Cohn wrote:


Turns out the problem was that the project contains only C code, whereas I was linking with libraries containing C++
c.f.: http://lists.apple.com/archives/xcode-users/2005/Nov/ msg00707.html
(Thanks to Eric Albert for that post!)


This gets me down to one link error:

___cxa_get_exception_ptr referenced from OSServices expected to be defined in libstdc++

... does anyone know why this one reference would be unresolved? or why it's not in stdc++?

Thanks once more,
--Dave




On Aug 24, 2006, at 8:54 AM, David Cohn wrote:



from http://lists.apple.com/archives/xcode-users/2005/Jul/ msg00495.html:


If you are compiling C++, the compiler automatically links against the appropriate C++ standard librari


from http://lists.apple.com/archives/xcode-users/2005/Jul/ msg00538.html:


If the stdc++ lib is not included, just add it to your projet as you do for all other liibraries.


No, don't do this.

We omit this from the UI and from the project templates for a reason.

The compiler "owns" the definition of the C++ standard library, because the use of the library is tightly coupled with C++ code generation. So the compiler determines, based on your code model, what library functions to link to. Let the compiler do its job.



Does anyone have any further information, clues, hints on how these linkage errors may arise?

- If linkage is automatic, how can one get linkage errors which seem to involve standard c++ symbols?
- Is there a way to tell from the build transcript what may be going on here?
- Can one get such link errors from conflicts in linked libs compiled in different projects? (e.g. different target SDKs?)


Any thoughts appreciated, and thanks!
--Dave



Hey all,

(I'm using Xcode 2.4, building a project for archs "ppc i386".)

I've read the thread "Re: linking against stdandard libraries":
	http://lists.apple.com/archives/xcode-users/2005/Jul/msg00495.html

...which states that linking with Standard C libraries should be
automatic, but I'm having trouble with some pesky "Undefined symbols"
which go away if I manually link stdc++:


	___gxx_personality_v0
	vtable for __cxxabiv1::__class_type_info
	vtable for __cxxabiv1::__si_class_type_info
	___cxa_pure_virtual
	vtable for __cxxabiv1::__pointer_type_info
	___cxa_begin_catch
	___cxa_end_catch
	vtable for __cxxabiv1::__vmi_class_type_info
	___cxa_allocate_exception
	___cxa_throw


I have LINK_WITH_STANDARD_LIBRARIES set, and can't find any other settings which seem to affect this.

...so my questions are:
- under what circumstances are the Standard Libraries passed or not?
- can I examine the Ld command line to verify what's happening?
(i.e. what parameters would show the standard libraries being passed,
or should I be seeing an explicit "-L" parameter for the requisite
standard libs?)

Thanks,
--Dave












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