Go type not supported in export: lingua.Language

I would like to call lingua-go functions from C++ code

I tried to generate h file and so file for this code ( following the indications found here: https://github.com/vladimirvivien/go-cshared-examples)

basic.go :

package main

import "C"

import (
        "github.com/pemistahl/lingua-go"
)

var lan lingua.Language

//export Langdetectfunct
func Langdetectfunct(text string) lingua.Language {

    detector := lingua.NewLanguageDetectorBuilder().
        FromAllLanguages().
        Build()

    if language, exists := detector.DetectLanguageOf(text); exists {
        lan = language
    }
    lan = lingua.English

    return lan

}

func main() {}

Doing:

raphy@raohy:~/go-lang-detect$ go build -o basic.so -buildmode=c-shared basic.go

I get :

raphy@raohy:~/go-lang-detect$ go build -o basic.so -buildmode=c-shared basic.go
# command-line-arguments
./basic.go:14:35: Go type not supported in export: lingua.Language

Thanks to the help of a member of the golang-team (https://github.com/golang/go/issues/65842) I learned that, since the Language type is based on int, I can convert the result of the function to an int with int(lan), being then able to export it and use it in a C/C++ piece of code:

package main

import "C"

import (
    "github.com/pemistahl/lingua-go"
)

var lan lingua.Language

//var lan int

//export Langdetectfunct
func Langdetectfunct(text string) int {

   detector := lingua.NewLanguageDetectorBuilder().
        FromAllLanguages().
        Build()

    if language, exists := detector.DetectLanguageOf(text); exists {
       lan = language
    }
    lan = lingua.English

   return int(lan)

}

func main() {}

Building with c-shared buildmode:

raphy@raohy:~/go-lang-detect$ go build -o basic.so -buildmode=c-shared 
basic.go

I obtain both h and so containing the Langdetectfunct function :

basic.h :

/* Code generated by cmd/cgo; DO NOT EDIT. */

/* package command-line-arguments */

#line 1 "cgo-builtin-export-prolog"

#include <stddef.h>

#ifndef GO_CGO_EXPORT_PROLOGUE_H
#define GO_CGO_EXPORT_PROLOGUE_H

#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef struct { const char *p; ptrdiff_t n; } _GoString_;
#endif

#endif

/* Start of preamble from import "C" comments.  */

/* End of preamble from import "C" comments.  */

/* Start of boilerplate cgo prologue.  */
#line 1 "cgo-gcc-export-header-prolog"

#ifndef GO_CGO_PROLOGUE_H
#define GO_CGO_PROLOGUE_H

typedef signed char GoInt8;
typedef unsigned char GoUint8;
typedef short GoInt16;
typedef unsigned short GoUint16;
typedef int GoInt32;
typedef unsigned int GoUint32;
typedef long long GoInt64;
typedef unsigned long long GoUint64;
typedef GoInt64 GoInt;
typedef GoUint64 GoUint;
typedef size_t GoUintptr;
typedef float GoFloat32;
typedef double GoFloat64;
#ifdef _MSC_VER
#include <complex.h>
typedef _Fcomplex GoComplex64;
typedef _Dcomplex GoComplex128;
#else
typedef float _Complex GoComplex64;
typedef double _Complex GoComplex128;
#endif

/*
  static assertion to make sure the file is being used on architecture
  at least with matching size of GoInt.
*/
typedef char _check_for_64_bit_pointer_matching_GoInt[sizeof(void*)==64/8 ? 1:-1];

#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef _GoString_ GoString;
#endif
typedef void *GoMap;
typedef void *GoChan;
typedef struct { void *t; void *v; } GoInterface;
typedef struct { void *data; GoInt len; GoInt cap; } GoSlice;

#endif

/* End of boilerplate cgo prologue.  */

#ifdef __cplusplus
extern "C" {
#endif

extern GoInt Langdetectfunct(GoString text);

#ifdef __cplusplus
}
#endif

basic.so :

raphy@raohy:~/go-lang-detect$ file basic.so
basic.so: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=2368dc7620b47d7b9b8ba019796d66f76fe061b8, with debug_info, not stripped

raphy@raohy:~/go-lang-detect$ nm basic.so | grep -e "T Langdetectfunct"
0000000000241350 T Langdetectfunct

pemistahl / lingua-go

Go type not supported in export: lingua.Language #58