[vtkusers] OSX 10.6 TCL issue "libvtkRendering.5.4.dylib: GC capability mismatch" ( solution too )

[Sean McBride]

On 3/3/10 11:43 AM, David Gobbi said:

>The items that need checking are as follows:
>
>/System/Library/Frameworks/Tk.framework/Versions/8.5/Tk
>
>/System/Library/Frameworks/Tk.framework/Versions/8.5/Resources/Wish.app/
>Contents/MacOS/Wish
>
>I've run otool on them, but frankly don't know what to look for with
>respect to gc.

Me neither.  But it looks like Tk is built to support both GC and non-GC
(aka RR or Retain-Release). otool -oV output includes:

Contents of (__OBJC,__image_info) section
  version 0
    flags 0x2 GC RR

Doing this on Wish says "can't print objective-C information no
(__OBJC,__module_info) section".  So I'm not sure.

>Also: I can run Tk examples fine with the "vtk"
>executable (which is how I usually do it), but when I try running the
>examples with wish, I get the same "GC capability mismatch" that Brad
>reported.

Something somewhere must be built with GC on.

In any case, vtk correctly supports both RR and GC.  There's really no
reason not to always build it with -fobjc-gc (ie with support for
both).  This allows it to be linked to both GC and RR apps.

In fact, it might be wise for vtk to configure itself with -fobjc-gc by
default.  One problem is that this flag is supported only as of 10.5. 
But perhaps some CMake wizardry could be done to check the deployment
target and use -fobjc-gc only if it's >= 10.5.

-- 
____________________________________________________________
Sean McBride, B. Eng                 sean at rogue-research.com
Rogue Research                        www.rogue-research.com 
Mac Software Developer              Montréal, Québec, Canada