xcode 为什么我在这个简单的代码中得到“ld：警告：在 _main 中直接访问全局弱符号”？
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Why do I get "ld: warning: direct access in _main to global weak symbol" in this simple code?
提问by JavaRunner
It's very strange behavior in my Clang compiler. I use Xcode (OS X), all is up-to-date. Why am I getting this warning in that simple code? If I remove those two lines the warning hides.
在我的 Clang 编译器中这是非常奇怪的行为。我使用 Xcode (OS X)，一切都是最新的。为什么我在那个简单的代码中收到这个警告？如果我删除这两行，警告就会隐藏。
ld: warning: direct access in _main to global weak symbol std::__1::char_traits::eq(char, char) means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.
ld：警告：在 _main 中直接访问全局弱符号 std::__1::char_traits::eq(char, char) 意味着在运行时不能覆盖弱符号。这可能是由于使用不同的可见性设置编译不同的翻译单元造成的。
int main( int argc, char* argv[] ) {
std::string file = "test";
size_t pos = file.find( "a" );
return 0;
}
回答by sergej
See Controlling Symbol Visibility @ developer.apple.comfor details.
有关详细信息，请参阅控制符号可见性 @ developer.apple.com。
It looks like your libs (eg. the C++ standard library) and your code have been compiled with different visibility settings, at least, that is what the linker error message is saying.
看起来您的库（例如 C++ 标准库）和您的代码已使用不同的可见性设置编译，至少，链接器错误消息是这样说的。
To fix the warning, you should use the same visibility settings when compiling your code, eg -fvisibility=hidden.
要修复警告，您应该在编译代码时使用相同的可见性设置，例如-fvisibility=hidden.
