Nix build error for libsodium on OS X 10.10

nix-libsodium-error.txt

$ nix-env -i libsodium
installing ‘libsodium-1.0.2’
these derivations will be built:
  /nix/store/pa9m21c85f9ml6fqiax4wr98w5gg7wlv-libsodium-1.0.2.drv
building path(s) ‘/nix/store/np5xi3mfq0kq7ljvba87wkx2dy52732d-libsodium-1.0.2’
unpacking sources
unpacking source archive /nix/store/amvg9xj89mamj49rjgbyf2x94yvww5jc-libsodium-1.0.2.tar.gz
source root is libsodium-1.0.2
patching sources
configuring
configure flags: --disable-static --disable-dependency-tracking --prefix=/nix/store/np5xi3mfq0kq7ljvba87wkx2dy52732d-libsodium-1.0.2
checking build system type... x86_64-apple-darwin14.1.0
checking host system type... x86_64-apple-darwin14.1.0
checking for a BSD-compatible install... /nix/store/6vijxqbd78fm55q69nzygqq8sff3qz2g-coreutils-8.23/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /nix/store/6vijxqbd78fm55q69nzygqq8sff3qz2g-coreutils-8.23/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
checking whether UID '501' is supported by ustar format... yes
checking whether GID '20' is supported by ustar format... yes
checking how to create a ustar tar archive... gnutar
checking whether make supports nested variables... (cached) yes
checking whether to enable maintainer-specific portions of Makefiles... no
checking for style of include used by make... GNU
checking for gcc... clang
checking whether the C compiler works... no
configure: error: in `/private/var/folders/lq/z7cmc8410r5gnlt6m8yrq1zm0000gn/T/nix-build-libsodium-1.0.2.drv-0/libsodium-1.0.2':
configure: error: C compiler cannot create executables
See `config.log' for more details
builder for ‘/nix/store/pa9m21c85f9ml6fqiax4wr98w5gg7wlv-libsodium-1.0.2.drv’ failed with exit code 77
error: build of ‘/nix/store/pa9m21c85f9ml6fqiax4wr98w5gg7wlv-libsodium-1.0.2.drv’ failed