Go 1.10+ supports building Windows DLLs via -buildmode=c-shared, enabling seamless interop with C/C++ applications—no MSVC header dependency required if only C-compatible types are exposed.

go 1.10+ supports building windows dlls via `-buildmode=c-shared`, enabling seamless interop with c/c++ applications—no msvc header dependency required if only c-compatible types are exposed.

Starting with Go 1.10, Windows gained official support for c-shared build mode—making it possible to generate native Windows DLLs directly from Go code. This is a significant improvement over Go 1.7 (and earlier), where -buildmode=shared was explicitly unsupported on windows/amd64, as the original question correctly observed.

To build a DLL, use:

go build -o helloworld.dll -buildmode=c-shared main.go

This command produces two artifacts:

• helloworld.dll: The loadable dynamic library.
• helloworld.h: A C header declaring exported functions (e.g., void Hello(void)), generated automatically and compatible with GCC-based toolchains (e.g., MinGW-w64).

⚠️ Important notes:

• Your Go source must export functions using //export comments and declare them with C-compatible signatures (e.g., no Go slices, maps, or structs with unexported fields). Only basic types (int, char*, void*) and C-style structs are safe.
• While the generated .h file is designed for GCC, you can load the DLL in Visual Studio without it—using LoadLibrary and GetProcAddress—as long as your Go exports adhere strictly to C ABI conventions.
• The main package is required (not a library package), and must include import "C" and at least one //export-annotated function.

Example main.go:

package main

import "C"
import "fmt"

//export Hello
func Hello() {
    fmt.Println("Hello from Go DLL!")
}

//export Add
func Add(a, b int) int {
    return a + b
}

func main() {} // required, but not executed when loaded as DLL

After building, you can call Add from C++ like this:

#include <windows.h>
#include <iostream>

typedef int (*AddFunc)(int, int);

int main() {
    HMODULE h = LoadLibrary(L"helloworld.dll");
    if (h) {
        AddFunc add = (AddFunc)GetProcAddress(h, "Add");
        if (add) std::cout << add(3, 4) << "\n"; // prints 7
        FreeLibrary(h);
    }
}

In summary: Go 1.7 cannot produce Windows DLLs—but Go 1.10+ makes it straightforward and production-ready, provided you follow C-interop constraints. Always test exported functions with go test and validate calling conventions across your target toolchain.