C语言跨Windows/macOS实现const char*转UTF16及编译问题解决

我当前的实现方式不够规范且过于繁琐，有没有简单的方法可以在Windows和macOS平台实现ASCII到UTF16的转换？

注意：prUTF16Char类型我无法修改🙃

现有实现 #

前置代码 #

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#if defined(__APPLE__) && defined(__MACH__)
#include <xcselect.h>
#include <wchar.h>
#include <CoreFoundation/CoreFoundation.h>
typedef unsigned short int prUTF16Char;
#else
typedef wchar_t prUTF16Char;
#endif

#define WIDEN2(x) L ## x
#define WIDEN(x) WIDEN2(x)
#define PROJECT_NAME "foo"

功能函数 #

void copy2ConvertStringLiteralIntoUTF16(const wchar_t* inputString, prUTF16Char* destination) {
    size_t length = wcslen(inputString);
#if (defined(_WIN32) || defined(__WIN32__) || defined(__WINDOWS__)) && defined(PLUGIN_MODE)
    wcscpy_s(destination, length + 1, inputString);
#elif defined(__APPLE__) && defined(__MACH__)
    CFRange range = {0, 150}; range.length = length;
    CFStringRef inputStringCFSR = CFStringCreateWithBytes(
        kCFAllocatorDefault, reinterpret_cast<const UInt8 *>(inputString),
        length * sizeof(wchar_t), kCFStringEncodingUTF32LE, false);
    CFStringGetBytes( inputStringCFSR, range, kCFStringEncodingUTF16, 0, false,
                      reiterpret_cast<UInt8 *>(destination), length * (sizeof (prUTF16Char)), NULL);
    destination[length] = 0; // Set NULL-terminator
    CFRelease(inputStringCFSR);
#endif
}

const prUTF16Char * to_wchar(const char* message) {
    const size_t cSize = strlen(message);
    wchar_t *w_str = new wchar_t[cSize];
#if defined(_WIN32) || defined(__WIN32__) || defined(__WINDOWS__)
    size_t outSize;
    mbstowcs_s(&outSize, w_str, cSize, message, cSize-1);
    return w_str;
#else
    mbstowcs(w_str, message, cSize);
#endif
#if defined(__APPLE__) && defined(__MACH__)
    prUTF16Char *ut16str = new prUTF16Char[cSize];
    copy2ConvertStringLiteralIntoUTF16(w_str, ut16str);
    return ut16str;
#else
    return w_str;
#endif
}

我之后定义了如下全局变量：

static const prUTF16Char* PROJECT_NAME_W =
#if defined(__APPLE__) && defined(__MACH__)
    to_wchar
#elif defined(_WIN32) || defined(__WIN32__) || defined(__WINDOWS__)
    WIDEN
#endif
        (PROJECT_NAME);

以及接收message参数的通用打印函数体：

#if WCHAR_UTF16
wprintf(L"%s",
#else
    printf("%ls\n",
#endif
    message);

完整代码目前正在从C++重写为C。

报错信息 #

error: initializer element is not a compile-time constant

临时兼容方案 #

目前我参考解决方案实现了如下临时兼容代码：

#if defined(__APPLE__) && defined(__MACH__)
extern
#elif defined(_WIN32) || defined(__WIN32__) || defined(__WINDOWS__)
static
#endif
const prUTF16Char* PROJECT_NAME_W
#if defined(__APPLE__) && defined(__MACH__)
    ;
#elif defined(_WIN32) || defined(__WIN32__) || defined(__WINDOWS__)
    WIDEN(PROJECT_NAME);
#endif

…并且仅对extern声明的变量执行初始化和free操作。

内容的提问来源于stack exchange，提问作者Samuel Marks