wxString is complicated by supporting win32's 16-bit wchar and 8-bit ansi dual-compile. You can get that problem on Windows if the "unicode" (meaning wchar) build is used, so that wxString is wchar and std::string is char.
It's probably some wxWidgets compile defines or build configuration. What "configure" options did you use?
我不确定 __WXMAC__ 是不是正确的宏。也许是 Mac Classic 支持把 wxString 搞复杂了，而我们只要 OSX。试试 __WXOSX__（或见下文）
I'm not sure __WXMAC__ is the right define. It may be the Mac Classic support that's complicating wxString, and we only want OSX. Try __WXOSX__ (or see below)
"wxWidgets 有两个移植到 Mac OS 的版本。其中一个 wxMac 又分两个版本：Classic 和 Carbon。Classic 版是唯一能跑在 Mac OS 8 上的。Carbon 版既可构建为 CFM 也可构建为 Mach-O（二进制格式，类似 ELF），前者或许能在 OS 9 下运行，后者只能在 OS X 下运行。最后还有一个只能在 OS X 下使用的新 Cocoa 移植。总结一下：
"There are two wxWidgets ports to Mac OS. One of them, wxMac, exists in two versions: Classic and Carbon. The Classic version is the only one to work on Mac OS version 8. The Carbon version may be built either as CFM or Mach-O (binary format, like ELF) and the former may run under OS 9 while the latter only runs under OS X. Finally, there is a new Cocoa port which can only be used under OS X. To summarize:
* 如果要判断是否为任一 Mac 平台（classic 和 OS X），应同时检查 __WXMAC__ 和 __WXCOCOA__。
* If you want to test for all Mac platforms, classic and OS X, you should test both __WXMAC__ and __WXCOCOA__.
* 如果要判断是否为 OS X 下的任一 Mac GUI 移植版本，用 __WXOSX__。
* If you want to test for any GUI Mac port under OS X, use __WXOSX__.
* 如果要判断是否为 Mac OS X 下的任一移植版本（比如 wxGTK 以及 wxBase），用 __DARWIN__"
* If you want to test for any port under Mac OS X, including, for example, wxGTK and also wxBase, use __DARWIN__"
