build failed with `libstd-71b07a99.so: undefined symbol: clock_gettime`

[alsam]

Hello All,
Used to build the nightly smoothly, but today it failed with the messages:

tail make.LOG2
cp x86_64-unknown-linux-gnu/rt/libcompiler-rt.a x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler-rt.a
MATCHES=""; if [ -n "$MATCHES" ] ; then echo "warning: removing previous" \'libcore-*.so\' "libraries:" $MATCHES; rm $MATCHES ; fi
MATCHES=""; if [ -n "$MATCHES" ] ; then echo "warning: removing previous" \'libcore-*.rlib\' "libraries:" $MATCHES; rm $MATCHES ; fi
CFG_LLVM_LINKAGE_FILE=/home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/rt/llvmdeps.rs LD_LIBRARY_PATH=/home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/stage1/lib:$LD_LIBRARY_PATH   x86_64-unknown-linux-gnu/stage1/bin/rustc --cfg stage1  -O --cfg rtopt -C prefer-dynamic --target=x86_64-unknown-linux-gnu  -D warnings -L "x86_64-unknown-linux-gnu/rt" -L native="/home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/llvm/Release/lib"      --out-dir x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib -C extra-filename=-71b07a99 src/libcore/lib.rs
info: now are following matches for libcore-*.so libraries:
info: now are following matches for libcore-*.rlib libraries:
x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-71b07a99.rlib
LD_LIBRARY_PATH=/home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/stage1/lib:$LD_LIBRARY_PATH   x86_64-unknown-linux-gnu/stage1/bin/rustc --cfg stage1  -O --cfg rtopt -C prefer-dynamic --target=x86_64-unknown-linux-gnu  --emit=obj -o x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/rsbegin.o /home/asamoilo/work/github/rust/src/rtstartup/rsbegin.rs
x86_64-unknown-linux-gnu/stage1/bin/rustc: symbol lookup error: /home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/stage1/lib/libstd-71b07a99.so: undefined symbol: clock_gettime
make: *** [x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/rsbegin.o] Error 127

running it manually:

D_LIBRARY_PATH=/home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/stage1/lib:$LD_LIBRARY_PATH   x86_64-unknown-linux-gnu/stage1/bin/rustc --cfg stage1  -O --cfg rtopt -C prefer-dynamic --target=x86_64-unknown-linux-gnu  --emit=obj -o x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/rsbegin.o /home/asamoilo/work/github/rust/src/rtstartup/rsbegin.rs
x86_64-unknown-linux-gnu/stage1/bin/rustc: symbol lookup error: /home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/stage1/lib/libstd-71b07a99.so: undefined symbol: clock_gettime

ldd /home/asamoilo/work/github/rust/x86_64-unknown-linux-gnu/stage1/lib/libstd-71b07a99.so
        linux-vdso.so.1 =>  (0x00007fff5f5ff000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f68f345e000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f68f3240000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f68f302a000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f68f2c97000)
        /lib64/ld-linux-x86-64.so.2 (0x00000031c6600000)
        libm.so.6 => /lib64/libm.so.6 (0x00007f68f2a12000)

Don't you think adding -lrt to libstd-*.so solve the problem?
Thanks!

[sfackler]

cc @alexcrichton probably fallout from #29894?

[alsam]

Thanks a lot.
I've read comments carefully and have got that the changes to libc in nursery that is an additional -lrt
https://github.com/rust-lang-nursery/libc/pull/66/files#r45526364
have already shipped. Unfortunately my rust sandbox stuck to the previous version of
./src/liblibc/src/unix/mod.rs after ./configure script.
Anyway editing manually the above file:

+        #[link(name = "rt")]

solved the issue.

[alsam]

Closing as the problem has been resolved.
Thanks!