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Bug 215085

Summary: dev-games/ogre - Fix --as-needed with cg
Product: Gentoo Linux Reporter: James Le Cuirot <chewi>
Component: [OLD] GamesAssignee: Gentoo Games <games>
Status: RESOLVED FIXED    
Severity: normal CC: Sander.Sweers
Priority: High    
Version: unspecified   
Hardware: All   
OS: Linux   
URL: http://www.ogre3d.org
Whiteboard:
Package list:
Runtime testing required: ---
Bug Depends on:    
Bug Blocks: 129413    
Attachments: ogre-1.4.7.ebuild
ogre-1.4.7-as-needed.patch

Description James Le Cuirot gentoo-dev 2008-03-27 17:43:07 UTC
Because of the way NVIDIA linked their Cg toolkit, building Ogre with the cg USE flag enabled and -Wl,--as-needed in your LDFLAGS doesn't work. Here's a new ebuild that filters the flags.
Comment 1 James Le Cuirot gentoo-dev 2008-03-27 17:44:29 UTC
Created attachment 147461 [details]
ogre-1.4.7.ebuild

Probably no point in incrementing the revision number.
Comment 2 Mr. Bones. (RETIRED) gentoo-dev 2008-04-08 16:47:40 UTC
in portage.  thanks for the bug report and patch.
Comment 3 Sander Sweers 2008-04-08 17:00:42 UTC
Filtering --as-needed is just hiding a bug. It should either be left open or fixed.
Comment 4 Mr. Bones. (RETIRED) gentoo-dev 2008-04-08 17:04:37 UTC
talk is cheap - patches welcome.
Comment 5 James Le Cuirot gentoo-dev 2008-04-08 17:24:18 UTC
The command that causes the error is...

gcc -o conftest <CFLAGS> -Wl,--as-needed conftest.c -lCg -lILU -lIL -lpthread -lz -lm -ldl

If you add (or move) -lpthread and -lm before the -Wl,--as-needed option then it works. Maybe you could do some trick with -Wl,--no-as-needed but you'd have to make sure that -Wl,--as-needed is added again afterwards and ONLY when it is wanted. It could be done but it wouldn't be too pretty.

There are two lines in the configure script that add the -lCg option and they read LIBS="-lCg $LIBS". Maybe something could be done with this.
Comment 6 Sander Sweers 2008-04-08 18:43:22 UTC
(In reply to comment #4)
> talk is cheap - patches welcome.

Sigh...

(In reply to comment #5)
> The command that causes the error is...
> 
> gcc -o conftest <CFLAGS> -Wl,--as-needed conftest.c -lCg -lILU -lIL -lpthread
> -lz -lm -ldl
> 
> If you add (or move) -lpthread and -lm before the -Wl,--as-needed option then
> it works. 
> 
> There are two lines in the configure script that add the -lCg option and they
> read LIBS="-lCg $LIBS". Maybe something could be done with this.

Probably changing the linking order from LIBS="-lCg $LIBS" to LIBS="$LIBS -lCg" will fix it. But I am not able to test that for another week. Could you have a go at it?
Comment 7 James Le Cuirot gentoo-dev 2008-04-08 19:12:36 UTC
I tried putting -lCg in various places before but that didn't work. It makes sense that you have to move -lm and -lpthread because Cg doesn't reference them when it should and so they must be linked regardless of whether they appear to be needed.
Comment 8 James Le Cuirot gentoo-dev 2008-04-09 17:16:58 UTC
Created attachment 149213 [details, diff]
ogre-1.4.7-as-needed.patch

Okay I've come up with a very simple patch. We can get away with only modifying the configure test because libm and libpthread are actually "needed" by OGRE itself any other time that libCg is linked. Thanks to the way AC_CHECK_LIB works, it is easy to add extra arguments to the test. Apply this patch before the ce-gui patch. "-Xlinker --no-as-needed" was used rather than "-Wl,--no-as-needed" because the comma confuses autoconf. Sorry for the extra work, Mr Bones!