duplicate symbols for architecture x86_64

[isezen]

Hello,
I created a simple minimal R package to reproduce the following compile error. If I include the dqrng_distribution.h or similar files into more than one .cpp file, I'm getting the following error. I believe those functions are not inline in header files but I might be wrong. Is there a workaround to overcome this issue or did I stuck to a single .cpp file?

duplicate symbol __ZN5dqrng20random_64bit_wrapperIN10pcg_detail6engineIyoNS1_12xsl_rr_mixinIyoEELb0ENS1_15specific_streamIoEENS1_18default_multiplierIoEEEEE4seedEyy in:
    rcpp1.o
    stat.o
duplicate symbol __ZN5dqrng20random_64bit_wrapperINS_7xoshiroILm2ELa24ELa16ELa37EEEE4seedEyy in:
    rcpp1.o
    stat.o
duplicate symbol __ZN5dqrng20random_64bit_wrapperINS_7xoshiroILm4ELa17ELa45ELa0EEEE4seedEyy in:
    rcpp1.o
    stat.o
duplicate symbol __ZN5dqrng20random_64bit_wrapperIN5sitmo15threefry_engineIyLm64ELm20EEEE4seedEyy in:
    rcpp1.o
    stat.o
ld: 4 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[LTLA]

I can't even get it to compile, let alone link. It seems xoshiro.h could do with:

#include <functional>
#include <algorithm>
#include <type_traits> // just in case.

... while your stat.hpp needs:

#include <functional>
#include <vector>

Presumably your compiler drags in those headers with something else that got #included, so you don't see a problem, but other implementations may not do so. In this case, I'm failing with GCC 7.4.0.

Anyway, onto the actual problem. The template specialized functions in dqrng_generator.h need to be inlined to bypass the one-definition rule. See #29; I didn't do them all, but we probably should.

[isezen]

similar problem exist here, too.

dqrng/inst/include/convert_seed.h

Lines 23 to 38 in 816de86

	template<>
	uint16_t right_shift<32, uint16_t>(uint16_t val) { return 0; } // # nocov
	template<>
	uint32_t right_shift<32, uint32_t>(uint32_t val) { return 0; } // # nocov
	template<int SHIFT, typename UIN>
	UIN left_shift(UIN val) {
	return val << SHIFT;
	}
	template<>
	uint16_t left_shift<32, uint16_t>(uint16_t val) { return 0; } // # nocov
	template<>
	uint32_t left_shift<32, uint32_t>(uint32_t val) { return 0; } // # nocov