CODEWITHSUNDEEP
xcodelinker
zneak
zneak

Reputation: 138251

How can I tell why my program requires a specific shared library?

I'm working on an OS X application using a third-party framework. This framework is distributed both as shared objects and static objects. For my purposes, I want to use the static objects because I can't rely on the presence of the library on other systems.

However, when I build the application with Xcode, something decides it needs the shared objects, and when I run it, dyld tells me off before I even get to my program:

dyld: Library not loaded: /usr/local/lib/libshared.dylib
  Referenced from: /Users/me/Library/Developer/Xcode/snip/Application.app/Contents/MacOS/Application
  Reason: image not found

I ran otool -L on the executable, and sure enough, it tried to link against the shared objects (which aren't even installed on my system). However, when I ran it on the thirty-some .a files that I link against, none of them indicated any dependency on them.

Apple's ld -v is just a tad verbose: it displays the library search paths but doesn't produce any other kind of useful output.

How can I find what tried to link against the shared objects?

Upvotes: 1

Views: 104

Answers (2)

zneak
zneak

Reputation: 138251

otool -L does list the libraries against which any object links.

This specific instance was caused by an Xcode bug (known as rdar://2725744 to the ones blessed with Apple bug database access, and not fixed as of Xcode 6.1.1) where if you try to link against a .a static library with Xcode but there's a .dylib (or .so) dynamic library with the same name in the same directory, the linker will pick the dynamic one.

When you instruct Xcode to link against a static library (say /some/path/to/my/libFooBar.a), it adds -L/some/path/to/my -lFooBar to the linker invocation. However, with it, ld first searches for a dynamic library called libFooBar.dylib, and it will fall back to the static library only if it can't find the dynamic one.

Upvotes: 1

Walt Sellers
Walt Sellers

Reputation: 3939

If you added the framework is listed in the "Build Phases" of "Link Binary with Libraries" and it has the setting of "Required" that could explain why the launch fails.

Try changing the setting to "Optional". Then if nothing uses the framework, it should launch fine. (If something tries to use the framework, but fails to check for it first, it might crash.)

Upvotes: 0

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