Still can't build statically on Linux

[arielf]

Describe the bug

Following the build instructions for static linking of vw

Don't end up with a statically linked executable in build/vowpalwabbit/vw

To Reproduce

Steps to reproduce the behavior:

1. CMAKE_OPTS='-DCMAKE_BUILD_TYPE=Release -DSTATIC_LINK_VW=ON'
2. make clean
3. mkdir -p build
4. ( cd build && cmake .. ${CMAKE_OPTS} )
5. make VERBOSE=1 -j
6. file build/vowpalwabbit/vw
   Outputs:

build/vowpalwabbit/vw: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/l, for GNU/Linux 3.2.0, BuildID[sha1]=94e1e27f8b5f324b626fd92ad47521d46bb1479b, not stripped

Expected behavior

file build/vowpalwabbit/vw should say the executable is statically linked

Observed Behavior

file build/vowpalwabbit/vw says the executable is dynamically linked

Environment

What version of VW did you use? latest https://github.com/VowpalWabbit/vowpal_wabbit/ HEAD as of 2019-04-05
What OS or language did you use? Ubuntu 18.04, c++

Additional context

Related things I noticed:

Flags are sometimes specified as On and sometimes as ON in the CMakeLists.txt files and documentation. The cmake documentation like this seem to imply that cmake variables are case sensitive and the two are not the same. Changing everything to ON in my build tree, doesn't seem to be sufficient to fix the issue though.

CMakeLists.txt also defines a switch set(unix_static_flag -static) but I'm not able to find where is this setting is being used.

Several test/unit_test/*.cc files have:

#ifndef STATIC_LINK_VW
#define BOOST_TEST_DYN_LINK
#endif

Wouldn't this ifndef always be false, given that both OFF and ON define this variable?
Is this mixing of C-preprocessor variables and Cmake variable a bug?

[jackgerrits]

Hi @arielf,

I just looked into this and it seems like #1807 regressed this. Was a really simple typo that made it through. I've put out a PR to fix it.

Here is the output for file build/vowpalwabbit/vw I got:

vowpalwabbit/vw: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), statically linked, for GNU/Linux 2.6.32, BuildID[sha1]=8ad541cb9beb89066299c61ad2bde713c668697e, not stripped

[arielf]

Thanks @jackgerrits for the debug and quick fix. Highly appreciated!

[kumpera]

Sorry for that. Cmake is really weird :(

[arielf]

No problem @kumpera . Thanks for all you work improving vw !