Hi everyone,

I am trying to implement threading on my local machine. Everything works fine with CmdStan. I can compile models, sample and use stansummary etc.

However, as soon as I had the flags:

```
echo "CXXFLAGS += -DSTAN_THREADS" > make/local
echo "CXXFLAGS += -pthread" >> make/local
```

CmdStan doesn’t compile models, with the following ouput for the `examples/bernoulli/bernoulli.stan`

(same error output for McElreath map_rect turorial)

```
--- Translating Stan model to C++ code ---
bin/stanc --o=examples/bernoulli/bernoulli.hpp examples/bernoulli/bernoulli.stan
Model name=bernoulli_model
Input file=examples/bernoulli/bernoulli.stan
Output file=examples/bernoulli/bernoulli.hpp
--- Compiling, linking C++ code ---
g++ -DSTAN_THREADS -pthread -std=c++1y -pthread -Wno-sign-compare -O3 -I src -I stan/src -I stan/lib/stan_math/ -I stan/lib/stan_math/lib/eigen_3.3.3 -I stan/lib/stan_math/lib/boost_1.69.0 -I stan/lib/stan_math/lib/sundials_4.1.0/include -DBOOST_RESULT_OF_USE_TR1 -DBOOST_NO_DECLTYPE -DBOOST_DISABLE_ASSERTS -DBOOST_PHOENIX_NO_VARIADIC_EXPRESSION -c -x c++ -o examples/bernoulli/bernoulli.o examples/bernoulli/bernoulli.hpp
g++ -DSTAN_THREADS -pthread -std=c++1y -pthread -Wno-sign-compare -O3 -I src -I stan/src -I stan/lib/stan_math/ -I stan/lib/stan_math/lib/eigen_3.3.3 -I stan/lib/stan_math/lib/boost_1.69.0 -I stan/lib/stan_math/lib/sundials_4.1.0/include -DBOOST_RESULT_OF_USE_TR1 -DBOOST_NO_DECLTYPE -DBOOST_DISABLE_ASSERTS -DBOOST_PHOENIX_NO_VARIADIC_EXPRESSION examples/bernoulli/bernoulli.o src/cmdstan/main.o stan/lib/stan_math/lib/sundials_4.1.0/lib/libsundials_nvecserial.a stan/lib/stan_math/lib/sundials_4.1.0/lib/libsundials_cvodes.a stan/lib/stan_math/lib/sundials_4.1.0/lib/libsundials_idas.a -o examples/bernoulli/bernoulli
/usr/bin/ld: _ZN4stan4math22AutodiffStackSingletonINS0_4variENS0_15chainable_allocEE9instance_E: TLS definition in examples/bernoulli/bernoulli.o section .tbss._ZN4stan4math22AutodiffStackSingletonINS0_4variENS0_15chainable_allocEE9instance_E[_ZN4stan4math22AutodiffStackSingletonINS0_4variENS0_15chainable_allocEE9instance_E] mismatches non-TLS reference in src/cmdstan/main.o
src/cmdstan/main.o: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
make/program:38: recipe for target 'examples/bernoulli/bernoulli' failed
make: *** [examples/bernoulli/bernoulli] Error 1
```

Could there be some `g++`

depencies missing?

Reinstalling CmdStan does not solve this issue.

Thank you for your help!

Please provide this additional information in addition to your question:

- Operating System: Ubuntu 18.04.3
- CmdStan Version: 2.20.0
- Compiler/Toolkit: g++