SWIG issue 1001

CMakeLists.txt

cmake_minimum_required(VERSION 3.14)
project(swig_test C)
include("${CMAKE_BINARY_DIR}/conanbuildinfo.cmake")
conan_basic_setup()

find_package(PythonInterp REQUIRED)
find_package(PythonLibs REQUIRED)
find_package(SWIG REQUIRED)

include_directories(${PYTHON_INCLUDE_DIR})
link_libraries(${PYTHON_LIBRARIES})

cmake_policy(SET CMP0078 NEW)
cmake_policy(SET CMP0086 NEW)
include(UseSWIG)

swig_add_library(mymod TYPE MODULE LANGUAGE python SOURCES example.i example.c)

option(WITH_CSHARP "Add C#")

if(WITH_CSHARP)
    enable_language(CSharp)
    add_executable(main main.cs)
endif()

conanfile.py

from conans import ConanFile, CMake


class Build(ConanFile):
    requires = ('swig_installer/4.0.1@madebr/testing',)

    settings = 'os', 'arch', 'build_type', 'compiler',
    generators = 'virtualenv', 'cmake',

    def build(self):
        print('settings.arch', str(self.settings.arch))
        cmake = CMake(self)
        cmake.configure()
        cmake.build()

example.c

/* File : example.c */

double  My_variable  = 3.0;

/* Compute factorial of n */
int  fact(int n) {
	if (n <= 1) return 1;
	else return n*fact(n-1);
}

/* Compute n mod m */
int my_mod(int n, int m) {
	return(n % m);
}

example.i

/* File : example.i */
%module example
%{
/* Put headers and other declarations here */
extern double My_variable;
extern int    fact(int);
extern int    my_mod(int n, int m);
%}

extern double My_variable;
extern int    fact(int);
extern int    my_mod(int n, int m);

main.cs

using System;

namespace ConsoleApp1
{
    class Program
    {
    static void Main(string[] args)
    {
        Console.WriteLine("Hello, world!");
    }
    }
}