clang++ cannot compile even a hello world program in Fedora

你們都說clang好，於是我就十分想試一試。我手上的機器只有fedora 17、CentOS 4/5/6。CentOS的repositories裡面沒有clang。但是fedora 17裡面有，於是我就興致勃勃的裝了一個。結果發現，連最簡單的Hello World都編譯不過去。   [changming@test 1]$ clang++ hello.cpp  In file included from hello.cpp:1:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/iostream:39:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ostream:39:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ios:42:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/bits/ios_base.h:40:  /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ext/atomicity.h:48:45: error: use of undeclared        identifier ‘__ATOMIC_ACQ_REL’    { return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }                                              ^  /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ext/atomicity.h:52:38: error: use of undeclared        identifier ‘__ATOMIC_ACQ_REL’    { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }                                       ^  2 errors generated.  [changming@test14 1]$ clang hello.cpp  In file included from hello.cpp:1:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/iostream:39:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ostream:39:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ios:42:  In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/bits/ios_base.h:40:  /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ext/atomicity.h:48:45: error: use of undeclared        identifier ‘__ATOMIC_ACQ_REL’    { return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }                                              ^  /usr/bin/../lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/ext/atomicity.h:52:38: error: use of undeclared        identifier ‘__ATOMIC_ACQ_REL’    { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); }