当使用LLVM的libc ++时，__1符号是从哪里来的？ [英] Where does the __1 symbol come from when using LLVM's libc++?

问题描述

我看到很多问题，例如 Apple Mach-O Linker（Id）错误和在IOS 64位项目的cryptopp中的未定义符号。问题通常描述为：

I see a fair amount of questions like Apple Mach-O Linker (Id) Error and Undefined symbols in cryptopp at IOS 64-bit project. The problem is usually described as:

Undefined symbols for architecture i386:
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >::flush()", referenced from:
      cv::gpu::error(char const*, char const*, int, char const*) in opencv2(gpumat.o)

问题通常会减少到混合/匹配 -stdlib = libc ++ （LLVM C ++ runtime）和 -stdlib = libstdc ++ （GNU C ++ runtime）。 LLVM C ++运行时（ libc ++ ）有一个 __ 1 装饰符号，但GNU C ++运行时 libstdc ++ __ 1 符号。它会导致看起来具有相同名称的符号的链接器问题（例如 std :: string ）。

The problem often reduces to mixing/matching -stdlib=libc++ (LLVM C++ runtime) and -stdlib=libstdc++ (GNU C++ runtime). The LLVM C++ runtime (libc++) has an __1 decoration symbol, but the GNU C++ runtime libstdc++ lacks the __1 symbol in its name. It causes linker problems for symbols that appears to have the same name (like std::string).

__ 1 符号是否来自使用LLVM的libc ++？

Where does the __1 symbol come from when using LLVM's libc++?

为什么不是使用 gnu 命名空间和 llvm 命名空间解决？

Why was the problem not solved with a gnu namespace and an llvm namespace?

这里有一个相关问题： libc ++ - 停止std重命名为std :: __ 1？。

Here's a related question: libc++ - stop std renaming to std::__1?. But it kind of misses the point in that a rename does not occur.

推荐答案

这是来自C ++ 11内联的命名空间

It is from C++11 inlined namespaces

libc ++有类似

libc++ has something like

namespace std {
    inline namespace __1 {
        ....

/stackoverflow.com/questions/11016220/what-are-inline-namespaces-for \">什么是内联命名空间？

more at What are inline namespaces for?

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