[Interest] Link failure with undefined references, on Ubuntu but not macOS

[Thiago Macieira]

On Wednesday, 29 April 2020 15:16:49 PDT Ben Haller via Interest wrote:
> -ltskit -lQt5OpenGL -lQt5Widgets -lQt5Gui -lQt5Core -lGL -lpthread
> 
> And here’s the beginning of the link errors, of which there are a fair
> number:
> 
> /home/bhaller/Desktop/SLiM_QMAKE_5142/QtSLiM/../eidos//libeidos.a(eidos_glob
> als.o): In function `_Eidos_FlushZipBuffer(std::__cxx11::basic_string<char,
> std::char_traits<char>, std::allocator<char> > const&,
> std::__cxx11::basic_string<char, std::char_traits<char>,
> std::allocator<char> > const&)': 
> eidos_globals.cpp:(.text+0x432): undefined reference to `z_gzopen'
> eidos_globals.cpp:(.text+0x44f): undefined reference to `z_gzbuffer'
> eidos_globals.cpp:(.text+0x461): undefined reference to `z_gzwrite'
> eidos_globals.cpp:(.text+0x474): undefined reference to `z_gzclose_w'

-lz is missing on your linker command-line.

> chromosome.cpp:(.text+0x3f): undefined reference to `gsl_ran_discrete_free'
> chromosome.cpp:(.text+0x4d): undefined reference to `gsl_ran_discrete_free'
> chromosome.cpp:(.text+0x5b): undefined reference to `gsl_ran_discrete_free'
> chromosome.cpp:(.text+0x69): undefined reference to `gsl_ran_discrete_free'
> chromosome.cpp:(.text+0x77): undefined reference to `gsl_ran_discrete_free’

Some other library also missing. I don't have this symbol in any library on my 
system so I can't offer you a suggestion. Please consult the its documentation 
(since you're using it, you must know it) and figure out what it is called so 
you can link.

Though I do note you have -lgsl on your linker line. If this is the right 
library, then check if the library has those symbols (nm -D if it's an .so, nm 
if it's .a).

> gsl: a statically linked C library (an edited version of the GNU GSL
> library)
> eidos_zlib: a statically linked C library (an edited version of the standard
> zlib library)

If libraries are static, the order in the linker command-line matters. The 
library must appear after the object that requires it.

For example, for:
   obj.o -lA -lB

obj.o can depend on libA.a and libB.a; libA.a can depend on libB.a.

libB.a cannot depend on libA.a

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products