disallow user-defined function overloading

[bob-carpenter]

Danny Goldstein reported on stan-users that the following problem parses and code generates, but doesn't compile.

functions {

  real add_mul(int a, int b){
    return a + b * a + b;
  }

  vector add_mul(vector a, vector b){
    return a + b .* a + b;
  }

}

data {
  int N;
  vector[N] y;
  vector[N] x;
}

parameters {
  real sigma;
  real m;
  real b;
}

model {
  vector[N] f;
  f <- m * x + b;
  y ~ normal(f, sigma);
}

This produces the following error on the develop branch of cmdstan and stan:

--- Linking C++ model ---
clang++ -DBOOST_RESULT_OF_USE_TR1 -DBOOST_NO_DECLTYPE -DBOOST_DISABLE_ASSERTS -I src -I stan/src -isystem stan/lib/stan_math_2.7.0 -isystem stan/lib/eigen_3.2.4 -isystem stan/lib/boost_1.58.0 -Wall -pipe -DEIGEN_NO_DEBUG -Wno-unused-function -Wno-tautological-compare -Wno-c++11-long-long -ftemplate-depth=256    -O0 -o /Users/carp/temp2/dg src/cmdstan/main.cpp -include /Users/carp/temp2/dg.hpp 
In file included from <built-in>:326:
In file included from <command line>:5:
/Users/carp/temp2/dg.hpp:71:8: error: redefinition of 'add_mul_functor__'
struct add_mul_functor__ {
       ^
/Users/carp/temp2/dg.hpp:41:8: note: previous definition is here
struct add_mul_functor__ {
       ^
1 error generated.

Either we need to figure out how to allow overloading, or have stanc catch the redeclaration and return an error.

[bgoodri]

I am continuing to think that appending the argument types to the C++ class name would work around this relatively easily
https://groups.google.com/d/msg/stan-users/arKMsfesJp0/ld_KVwj2YNUJ

[andreeleuterio]

Hi folks,
I have PyStan installed on a Linux environment with no internet connection, so I installed it from source.
I try running the basic Eight Schools example and keep getting the following output:
INFO:pystan:COMPILING THE C++ CODE FOR MODEL anon_model_95013624776d537c3cd7cd4d641c30e0 NOW. Traceback (most recent call last): File "eightschools.py", line 33, in <module> iter=1000, chains=4) File "/home/workgroups/reit/apps/python/2.7.7/pystan/2.9.0.0/lib/python2.7/site-packages/pystan/api.py", line 368, in stan verbose=verbose) File "/home/workgroups/reit/apps/python/2.7.7/pystan/2.9.0.0/lib/python2.7/site-packages/pystan/model.py", line 312, in __init__ build_extension.run() File "/apps/python/2.7.7/lib/python2.7/distutils/command/build_ext.py", line 337, in run self.build_extensions() File "/apps/python/2.7.7/lib/python2.7/distutils/command/build_ext.py", line 446, in build_extensions self.build_extension(ext) File "/apps/python/2.7.7/lib/python2.7/distutils/command/build_ext.py", line 496, in build_extension depends=ext.depends) File "/apps/python/2.7.7/lib/python2.7/distutils/ccompiler.py", line 574, in compile self._compile(obj, src, ext, cc_args, extra_postargs, pp_opts) File "/apps/python/2.7.7/lib/python2.7/distutils/unixccompiler.py", line 122, in _compile raise CompileError, msg distutils.errors.CompileError: command 'gcc' failed with exit status 1

I have the latest version of Pystan, with Stan 2.9.0. Also, I have RStan installed on the same environment and the same example runs fine.

Thank you in advance

[ariddell]

@aeleuterio would you mind opening an issue at the pystan repository? https://github.com/stan-dev/pystan/issues When you open an issue, please let us know what Linux distribution you're using and what version of gcc if you know it.

[andreeleuterio]

@ariddell Will do, I apologize for posting on the wrong forum