Notes
(0017940) Bill Hoffman (manager) 2009-10-04 19:36	So the pic in exe comes from some compilers other than gnu that do template instantiation during linking and so actually compile code during the link. Why is this a problem?

(0017942) Modestas Vainius (reporter) 2009-10-05 06:05	-fPIC enables Position Independent Code. Executables are not shared typically, their code does not need to be position independent contrary to shared libraries which are relocatable by definition. -fPIC is essential for shared libraries on GNU/Linux for all arches but i386. Linking executables with -fPIC is just wrong and even considered a policy violation on Debian. I didn't get what you meant in your note, but in this case -fPIC comes from CMAKE_SHARED_LIBRARY_C_FLAGS in Modules/Platform/gcc.cmake and Modules/Platform/gcc.cmake. I don't know about other platforms (and don't care) but this is how it works on GNU/Linux and should be supported properly. I have just confirmed the issue on unpatched cmake 2.8-rc2: CMakeLists.txt -------------- project(testproject C) cmake_minimum_required(VERSION 2.6) add_library(libtest SHARED test.c) add_executable(testexe test.c) Output ------ $ cmake . ..... $ make VERBOSE=1 .... Linking C shared library liblibtest.so /home/modax/src/cmake/cmake/builddir/bin/cmake -E cmake_link_script CMakeFiles/libtest.dir/link.txt --verbose=1 /mnt/sda2/usr/bin/gcc -fPIC -shared -Wl,-soname,liblibtest.so -o liblibtest.so CMakeFiles/libtest.dir/test.c.o .... That's OK. -fPIC is here as it should be. Linking C executable testexe /home/modax/src/cmake/cmake/builddir/bin/cmake -E cmake_link_script CMakeFiles/testexe.dir/link.txt --verbose=1 /mnt/sda2/usr/bin/gcc -fPIC CMakeFiles/testexe.dir/test.c.o -o testexe -rdynamic .... -fPIC is wrong here. I'm also told that -rdynamic here is redundant for most executables (check ld(1) docs for --export-dynamic). It increases executable size. Clearing CMAKE_SHARED_LIBRARY_C_FLAGS in Modules/Platform/gcc.cmake drops -fPIC from both add_library() and add_executable(). This is wrong. -rdynamic is passed via CMAKE_SHARED_LIBRARY_LINK_C_FLAGS in Modules/Platform/Linux.cmake

(0017944) Brad King (manager) 2009-10-05 09:56	In the bash-ism's patch, see this hunk: ---------------------------------------------------------------------------- diff --git a/Modules/CPack.RuntimeScript.in b/Modules/CPack.RuntimeScript.in index eaecdd8..f27444f 100755 --- a/Modules/CPack.RuntimeScript.in +++ b/Modules/CPack.RuntimeScript.in @@ -3,10 +3,10 @@ # Modified from: Aaron Voisine <aaron@voisine.org> CWD="`dirname \"$0\"`" -TMP=/tmp/$UID/TemporaryItems +TMP=/tmp/$(id -ru)/TemporaryItems ---------------------------------------------------------------------------- Isn't "$()" a bashism? Should it be +TMP="/tmp/`id -ru`/TemporaryItems" ?

(0017945) Brad King (manager) 2009-10-05 10:30 edited on: 2009-10-05 10:30	Applied FindQt3.cmake.diff: FindQt3: Prefer (moc\|uic)-qt3 names over (moc\|uic) /cvsroot/CMake/CMake/Modules/FindQt3.cmake,v <-- Modules/FindQt3.cmake new revision: 1.22; previous revision: 1.21 Applied desktop-remove-deprecated.diff: Remove old Encoding field from CMake.desktop /cvsroot/CMake/CMake/Source/QtDialog/CMake.desktop,v <-- Source/QtDialog/CMake.desktop new revision: 1.3; previous revision: 1.2 Applied kfreebsd-Platform.diff: Support GNU/kFreeBSD /cvsroot/CMake/CMake/Modules/CMakeDetermineSystem.cmake,v <-- Modules/CMakeDetermineSystem.cmake new revision: 1.30; previous revision: 1.29 /cvsroot/CMake/CMake/Modules/Platform/kFreeBSD.cmake,v <-- Modules/Platform/kFreeBSD.cmake new revision: 1.5; previous revision: 1.4 Applied manpage_friendly_docs.diff: Fix module docs to be manpage (groff) friendly /cvsroot/CMake/CMake/Modules/FindBISON.cmake,v <-- Modules/FindBISON.cmake new revision: 1.4; previous revision: 1.3 /cvsroot/CMake/CMake/Modules/FindFLEX.cmake,v <-- Modules/FindFLEX.cmake new revision: 1.3; previous revision: 1.2 /cvsroot/CMake/CMake/Modules/FindProtobuf.cmake,v <-- Modules/FindProtobuf.cmake new revision: 1.6; previous revision: 1.5 Applied scripts-and-permissions.diff: Fix permsissions of installed SquishRunTestCase.sh /cvsroot/CMake/CMake/CMakeLists.txt,v <-- CMakeLists.txt new revision: 1.163; previous revision: 1.162 Add '#!/bin/sh' to cygwin-package.sh /cvsroot/CMake/CMake/Templates/cygwin-package.sh.in,v <-- Templates/cygwin-package.sh.in new revision: 1.2; previous revision: 1.1

(0017952) Modestas Vainius (reporter) 2009-10-05 12:39	Re bashisms patch. Both are POSIX. See http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html [^] 2.6.3 Command Substitution

(0017955) Brad King (manager) 2009-10-05 13:15	Applied fix_bashisms.diff: CPack: Fix bash-isms in launch script /cvsroot/CMake/CMake/Modules/CPack.RuntimeScript.in,v <-- Modules/CPack.RuntimeScript.in new revision: 1.6; previous revision: 1.5

(0017966) Modestas Vainius (reporter) 2009-10-06 04:25	So I guess this bug could be renamed to "Executables should not be linked with flags of shared libraries". I also attach the description and the patch itself. From: Ben Hutchings <ben@decadent.org.uk> Subject: Do not use -fPIC when linking executables cmake includes ${CMAKE_SHARED_LIBRARY_C_FLAGS} in the command line to link an executable, and by default this is -fPIC. Either the use or the definition of this variable is wrong, because executables should not be linked with this option by default. . It's not entirely obvious how this variable gets into the command line, but you can verify that it does by changing its value to e.g. -D SHARED and running make VERBOSE=1. . Any special options needed for linking with shared libraries can be put in CMAKE_SHARED_LIBRARY_LINK_C_FLAGS. Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=478404 [^]

(0017970) Brad King (manager) 2009-10-06 10:17	I've traced down the history of the lines removed by the fPIC patch. They are the modern implementation of a change first made by this commit: Author: Bill Hoffman <bill.hoffman@kitware.com> Date: Thu Nov 14 01:14:05 2002 +0000 add support for borland run time flag for shared builds It's revision 1.30 of Source/cmLocalUnixMakefileGenerator.cxx: http://www.cmake.org/cgi-bin/viewcvs.cgi/Source/cmLocalUnixMakefileGenerator.cxx?root=CMake&r1=1.29&r2=1.30 [^] The relevant hunk looks like this: { rules.push_back(m_Makefile->GetDefinition("CMAKE_CXX_LINK_EXECUTABLE")); flags += this->GetSafeDefinition("CMAKE_CXX_FLAGS"); flags += " "; + flags += this->GetSafeDefinition("CMAKE_SHARED_LIBRARY_CXX_FLAGS"); + flags += " "; } The goal was to build shared libraries with the Borland 5.5 free command line tools. The "-tWR" flag is needed for both compilation and linking to enable use of the dynamic runtime library.

(0018031) Brad King (manager) 2009-10-08 11:57	I've committed totally new Borland support to avoid needing CMAKE_SHARED_LIBRARY_<lang>_FLAGS on the executable link line. Split Borland compiler information files /cvsroot/CMake/CMake/Modules/Platform/Windows-Borland-C.cmake,v <-- Modules/Platform/Windows-Borland-C.cmake initial revision: 1.1 /cvsroot/CMake/CMake/Modules/Platform/Windows-Borland-CXX.cmake,v <-- Modules/Platform/Windows-Borland-CXX.cmake initial revision: 1.1 /cvsroot/CMake/CMake/Modules/Platform/Windows-Borland.cmake,v <-- Modules/Platform/Windows-Borland.cmake initial revision: 1.1 /cvsroot/CMake/CMake/Modules/Platform/Windows-bcc32.cmake,v <-- Modules/Platform/Windows-bcc32.cmake new revision: delete; previous revision: 1.47 /cvsroot/CMake/CMake/Source/cmLocalGenerator.cxx,v <-- Source/cmLocalGenerator.cxx new revision: 1.320; previous revision: 1.319 /cvsroot/CMake/CMake/Tests/CMakeLists.txt,v <-- Tests/CMakeLists.txt new revision: 1.124; previous revision: 1.123

(0018032) Brad King (manager) 2009-10-08 11:57	Now I've applied the -fPIC patch: Do not use -fPIC to link executables /cvsroot/CMake/CMake/Source/cmMakefileExecutableTargetGenerator.cxx,v <-- Source/cmMakefileExecutableTargetGenerator.cxx new revision: 1.66; previous revision: 1.65

Issue History
Date Modified	Username	Field	Change
2009-10-04 17:27	Modestas Vainius	New Issue
2009-10-04 19:35	Bill Hoffman	Status	new => assigned
2009-10-04 19:35	Bill Hoffman	Assigned To	=> Brad King
2009-10-04 19:36	Bill Hoffman	Note Added: 0017940
2009-10-05 06:05	Modestas Vainius	Note Added: 0017942
2009-10-05 09:56	Brad King	Note Added: 0017944
2009-10-05 10:30	Brad King	Note Added: 0017945
2009-10-05 10:30	Brad King	Note Edited: 0017945
2009-10-05 12:39	Modestas Vainius	Note Added: 0017952
2009-10-05 13:15	Brad King	Note Added: 0017955
2009-10-06 04:25	Modestas Vainius	Note Added: 0017966
2009-10-06 04:26	Modestas Vainius	File Added: executables-dont-need-fpic.diff
2009-10-06 08:34	Brad King	Summary	Debian patches against 2.8-rc2 => Executables should not be linked with shared library compilation flags
2009-10-06 10:17	Brad King	Note Added: 0017970
2009-10-08 11:57	Brad King	Note Added: 0018031
2009-10-08 11:57	Brad King	Note Added: 0018032
2009-10-08 11:58	Brad King	Status	assigned => closed
2009-10-08 11:58	Brad King	Resolution	open => fixed
2010-01-12 17:10	Brad King	Relationship added	related to 0009985