ocamlopt is incapable of building files using clock_gettime with glibc older than 2.17

[JasonGross]

The OCaml 4.11.1 test-suite fails on Ubuntu Precise (12.04). Full logs are available here and here. The error message is:

 ... testing 'main.ml' with 1.1 (native) => failed (Compiling program /<<PKGBUILDDIR>>/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte/main.opt from modules  main.ml: command
/<<PKGBUILDDIR>>/runtime/ocamlrun /<<PKGBUILDDIR>>/ocamlopt  -I /<<PKGBUILDDIR>>/runtime  -nostdlib -I /<<PKGBUILDDIR>>/stdlib  -runtime-variant=i     -o /<<PKGBUILDDIR>>/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte/main.opt   main.ml 
failed with exit code 2)

By running this command locally in a VM with -verbose, I've discovered that the error is:

test@ubuntu:~/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte$ /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/ocamlrun /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/ocamlopt  -I /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime  -nostdlib -I /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib  -runtime-variant=i     -o /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte/main.opt -verbose  main.ml
+ i686-linux-gnu-as  -o 'main.o' '/tmp/camlasm412e31.s'
+ i686-linux-gnu-as  -o '/tmp/camlstartup184b86.o' '/tmp/camlstartupa4bb3d.s'
+ i686-linux-gnu-gcc -Wl,-z,notext -std=gnu99 -O2 -fno-strict-aliasing -fwrapv -fno-builtin-memcmp -Wall -Wdeclaration-after-statement -fexcess-precision=standard -fno-tree-vrp -ffunction-sections -D_FILE_OFFSET_BITS=64 -D_REENTRANT -DCAML_NAME_SPACE  -Wl,-E -o '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte/main.opt'  '-L/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime' '-L/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib'  '/tmp/camlstartup184b86.o' '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib/std_exit.o' 'main.o' '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib/stdlib.a' '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/libasmruni.a' -lm -ldl 
/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/libasmruni.a(eventlog_ni.o): In function `time_counter':
/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/eventlog.c:113: undefined reference to `clock_gettime'
collect2: ld returned 1 exit status
File "caml_startup", line 1:
Error: Error during linking (exit code 1)

According to https://stackoverflow.com/a/32649327/377022, versions of glibc older than 2.17 (ldd --version gives ldd (Ubuntu EGLIBC 2.15-0ubuntu10.6) 2.15 on this machine) require -lrt. However, even if I add -ccopt -lrt (which I should not have to do in the first place, I believe, as the test-suite should just work), this is not enough, because, according to https://stackoverflow.com/a/8088766/377022, -lrt must come after the object files, and instead it comes after the last -L but before the first object file. It seems there is no way to instruct ocamlopt to do this (unless I am missing something).

[JasonGross]

Btw, it seems that -S does not keep all intermediate assembly files:

test@ubuntu:~/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte$ /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/ocamlrun /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/ocamlopt  -I /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime  -nostdlib -I /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib  -runtime-variant=i     -o /home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte/main.opt -verbose main.ml -S
+ i686-linux-gnu-as  -o 'main.o' 'main.s'
+ i686-linux-gnu-as  -o '/tmp/camlstartupd25cd5.o' '/tmp/camlstartupfdecb2.s'
+ i686-linux-gnu-gcc -Wl,-z,notext -std=gnu99 -O2 -fno-strict-aliasing -fwrapv -fno-builtin-memcmp -Wall -Wdeclaration-after-statement -fexcess-precision=standard -fno-tree-vrp -ffunction-sections -D_FILE_OFFSET_BITS=64 -D_REENTRANT -DCAML_NAME_SPACE  -Wl,-E -o '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte/main.opt'  '-L/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime' '-L/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib'  '/tmp/camlstartupd25cd5.o' '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib/std_exit.o' 'main.o' '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/stdlib/stdlib.a' '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/libasmruni.a' -lm -ldl 
/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/libasmruni.a(eventlog_ni.o): In function `time_counter':
/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/eventlog.c:113: undefined reference to `clock_gettime'
collect2: ld returned 1 exit status
File "caml_startup", line 1:
Error: Error during linking (exit code 1)
test@ubuntu:~/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte$ ls /tmp/camlstartupfdecb2.s
ls: cannot access /tmp/camlstartupfdecb2.s: No such file or directory
test@ubuntu:~/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/testsuite/_ocamltest/tests/instrumented-runtime/main/ocamlopt.byte$ 

Is there any way to get access to the camlstartup assembly file, so I can actually test whether or not moving -lrt to the end works?

[nojb]

As mentioned in Discuss, I think you can use ocamlopt -dstartup to access the startup code.

[xavierleroy]

1- Seeing the startup code will not help you. Just look at the very long line generated by ocamlopt -verbose, the one starting with i686-linux-gnu-gcc -Wl,-z,notext. All the C libraries are listed there.
2- To pass an extra library, use -cclib -lxxx. -ccopt zzz is for C compiler options.
3- Ubuntu 12.04 LTS reached end of support on 28 April 2017. You're wasting your time, our time, and electricity by including it in your CI.

[JasonGross]

2- To pass an extra library, use -cclib -lxxx. -ccopt zzz is for C compiler options.

-cclib -lrt indeed moves -lrt later, but unfortunately not late enough. It gets moved to before '/home/test/coq-debian-build-scripts/ocaml-stuff/debian-sources/ocaml-4.11.1/runtime/libasmruni.a', but instead needs to come right after.

But, sure, this distribution reached end of support a while ago, and I can stop making Coq master packages for precise on launchpad.