Multiple definitions of `cxxopts::values::integer_pattern` about cxxopts

[SylvainCorlay]

cc @JohanMabille

[jarro2783]

I thought putting it in an anonymous namespace would fix it, and I also thought that I tested this.

Can you show me a snippet of code that breaks?

[SylvainCorlay]

OK, I can put one together tomorrow. This came up in a rather large project.

Basically, we are working on a C++ kernel for the Jupyter notebook, backed by the cling C++ interpreter:

We have a notion of "cell magic" that allows user to enter non-c++ commands to perform some operations (fetching help on a certain module etc).

We use cxxopts to parse options for these commands. So basically, our usecase is quite difference from the usual argument parsing for a command-line application but cxxopts does the job, hence the multiple compilation units.

[jarro2783]

This really sounds like a bug in the compiler if anything. I'm pretty sure that according to the standard, something declared in an anonymous namespace has internal linkage in the translation unit, so it shouldn't result in multiple references.

If you can give me some code that reproduces the problem then I can have a look at it.

[SylvainCorlay]

The code that breaks is the compilation of xeus-cling.

Building it locally is a bit cumbersome because it has a lot of dependencies which need to be built or for which you will need to get a binary package. (For this reason, I use the conda package manager for which I have built all the dependency tree).

I do get multiple versions of gcc (4.9, 5.x anx 6.x) to complain cxxopts::values::integer_pattern. However, I don't get why this should not work.

FYI, the version with a singleton does work and also prevents recompiling the regex.

[jarro2783]

In fact I'm not sure why you get an error with integer_pattern and not option_matcher, option_specifier.

[jarro2783]

I'm trying to build xeus-cling, to reproduce this. I followed the instructions on that repo to install conda, and cloned the xeus-cling source, but I'm stuck here:

cmake -DCMAKE_INSTALL_PATH=$HOME/miniconda3 -DCMAKE_INSTALL_LIBDIR=$HOME/miniconda3 .
-- The C compiler identification is GNU 7.1.1
-- The CXX compiler identification is GNU 7.1.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found LLVM_CONFIG as /home/jbeck/miniconda3/bin/llvm-config
CMake Error at /usr/lib/cmake/clang/ClangTargets.cmake:419 (message):
  The imported target "clangApplyReplacements" references the file

     "/usr/lib/libclangApplyReplacements.a"

What am I missing here?

[jarro2783]

I was never able to reproduce this, but it will be fixed when I address #281