They are not aliases but I cannot determine if there is a difference in functionality
~/Src/petsc next $ gcc --version Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1 Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-darwin13.0.0 Thread model: posix ~/Src/petsc next $ clang --version Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-darwin13.0.0 Thread model: posix ~/Src/petsc next $ ls -l /usr/bin/gcc -rwxr-xr-x 1 root wheel 14224 Oct 22 20:01 /usr/bin/gcc ~/Src/petsc next $ ls -l /usr/bin/clang -rwxr-xr-x 1 root wheel 14224 Oct 22 20:01 /usr/bin/clang ~/Src/petsc next $ diff /usr/bin/clang /usr/bin/gcc Binary files /usr/bin/clang and /usr/bin/gcc differ ~/Src/petsc next $ g++ --version Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1 Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-darwin13.0.0 Thread model: posix ~/Src/petsc next $ clang++ --version Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-darwin13.0.0 Thread model: posix ~/Src/petsc next $ diff /usr/bin/clang++ /usr/bin/g++ Binary files /usr/bin/clang++ and /usr/bin/g++ differ man gcc returns the manual page for gcc (with its huge number of crazy gnu specific stuff) while man clang gives back a smaller clang/llvm manual page. I guess someone needs to bite the bullet and test the gcc options that are not clang options and see if they work with /usr/bin/gcc If Xcode’s gcc does not support gcc options then we should not default to using it since that is way confusing! Barry On Oct 31, 2013, at 12:12 AM, Sean Farley <[email protected]> wrote: > > [email protected] writes: > >> On Thu, 31 Oct 2013, Sean Farley wrote: >> >>> >>> [email protected] writes: >>> >>>> unless everyone is using xcode5 - I think gcc/g++ is a safer default. >>> >>> Apple stopped shipping gcc with Xcode 4.2 [1]. Since that version, >>> everyone has been using the llvm backend. >> >> The isse is clang frontend with xcode4 is buggy [breaks with petsc build] >> >> http://lists.mcs.anl.gov/pipermail/petsc-dev/2013-October/thread.html > > It would appear so. > >>> Only in version >= 5.0 has >>> llvm-gcc been dropped. And in Mavericks only libc++ (and not libstdc++) >>> is shipped. >>> >>> [1] http://en.wikipedia.org/wiki/Xcode#Toolchain_Versions >> >> Since /usr/bin/gcc is an alias to clang in Xcode5 - there is no need >> to change defaults on OSX as Barry is suggesting? > > Probably, but I haven't tested.
