LLVM bug? Or Yosemite another bug?

Just try to use strncpy() in C and then to compile with:
Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn)
Target: x86_64-apple-darwin14.3.0
Thread model: posix

Btw. there is still no possibility to use the old good Valgrind under Yosemite... Cry, cry, cry...