[cmake-developers] [CMake 0012601]: CLang with Opiton -working-directory leads CMake to ommit fPIC in CXX_FLAGS for shared libs

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://public.kitware.com/Bug/view.php?id=12601 
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Reported By:                doob
Assigned To:                
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Project:                    CMake
Issue ID:                   12601
Category:                   CMake
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
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Date Submitted:             2011-11-30 06:58 EST
Last Modified:              2011-11-30 06:58 EST
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Summary:                    CLang with Opiton -working-directory leads CMake to
ommit fPIC in CXX_FLAGS for shared libs
Description: 
I tried using CLang as drop in replacement for GCC with CMake and it worked just
fine. (CLang Version 3.0) I just set CLang/CLang++ as the native C/CXX compiler
in CMake. 

However since qtcreator didn't recognized the paths given by warning and error
messages from CLang I forced CLang to output absolute paths always by setting
-working-directory "/" to output paths relative to the root directory. 

However this seams to fool some internal setup/path detection or whatever
process of CMake. If I use CLang together with -working-directory "/" I can't
build shared libraries anymore, because CMake somehow fails on setting the
proper fPIC flags then. 


Steps to Reproduce: 
On a shared library target building project:
- set clang/clang++ as the native C/CXX compiler in CMake
- build the project
---> everything should be fine
---> grep -l -R fPIC . will show you that fPIC is actually in the compile line.
Look into your ./**/flags.make files. 



- add -working-directory "/" to C/CXX flags in CMake
- make rebuild_cache
- build the project
---> linker complains about missing fPIC on your object files with something
like: relocation R_X86_64_32S against `.bss' can not be used when making a
shared object

---> grep -l -R fPIC . will show you that fPIC is missing in the compile line.
Look into your ./**/flags.make files. 



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Issue History 
Date Modified    Username       Field                    Change               
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2011-11-30 06:58 doob           New Issue                                    
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