LLVM/Clang++找不到<iostream>

Question

我的环境：

(posix)

• MinGW-W64：
• System: Windows 10
• LLVM: 12.0.0 (预建)与clang 12.0.0
• 4.3.4 (预建)与gcc 7.3.0 (posix)

MinGW-W64和LLVM都被添加到我的路径中。

当我尝试用clang++编译Hello时，它会大喊大叫：

clang++: warning: unable to find a Visual Studio installation; try running Clang from a developer command prompt [-Wmsvc-not-found]
test1.cpp:4:10: fatal error: 'iostream' file not found
#include <iostream>
         ^~~~~~~~~~
1 error generated.

当我添加-v时，它不会搜索g++ stdlib：

clang version 12.0.0
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: D:\.llvm12\bin
clang++: warning: unable to find a Visual Studio installation; try running Clang from a developer command prompt [-Wmsvc-not-found]
clang++: warning: argument unused during compilation: '-stdlib=libc++' [-Wunused-command-line-argument]
 "D:\\.llvm12\\bin\\clang++.exe" -cc1 -triple x86_64-pc-windows-msvc19.11.0 -emit-obj -mrelax-all -mincremental-linker-compatible --mrelax-relocations -disable-free -disable-llvm-verifier -discard-value-names -main-file-name test1.cpp -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -v -resource-dir "D:\\.llvm12\\lib\\clang\\12.0.0" -internal-isystem "D:\\.llvm12\\lib\\clang\\12.0.0\\include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 10.0/VC/include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 9.0/VC/include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 8/VC/include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include" -fdeprecated-macro -fdebug-compilation-dir "D:\\.tmp" -ferror-limit 19 -fmessage-length=120 -fno-use-cxa-atexit -fms-extensions -fms-compatibility -fms-compatibility-version=19.11 -std=c++14 -fdelayed-template-parsing -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -o "C:\\Users\\lenovo\\AppData\\Local\\Temp\\test1-4517aa.o" -x c++ test1.cpp
clang -cc1 version 12.0.0 based upon LLVM 12.0.0 default target x86_64-pc-windows-msvc
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 10.0/VC/include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 9.0/VC/include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 8/VC/include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include"
#include "..." search starts here:
#include <...> search starts here:
 D:\.llvm12\lib\clang\12.0.0\include
End of search list.
test1.cpp:4:10: fatal error: 'iostream' file not found
#include <iostream>
         ^~~~~~~~~~
1 error generated.

我是否安装了LLVM或MinGW-W64的错误版本？

编辑1：

我试图使用--target=x86_64-w64-windows-gnu编译一段明显错误的代码：

// test3.cpp
#include <iostream>
int main() {
    cout << "\n";
    return 0;
}

然后，它给了我一个令人满意的答复：

test3.cpp:4:2: error: use of undeclared identifier 'cout'; did you mean 'std::cout'?
        cout << "\n";
        ^~~~
        std::cout
D:\.mingw64\lib\gcc\x86_64-w64-mingw32\7.3.0\include\c++\iostream:61:18: note: 'std::cout' declared here
  extern ostream cout;          /// Linked to standard output
                 ^
1 error generated.

我想将--target=x86_64-w64-windows-gnu添加到我的默认设置中。我该怎么做呢？

Answer 1

在Windows上，Clang在默认情况下以与MSVC兼容的模式运行，使用其标准库和各种标头.

要使它在MinGW兼容模式下运行，添加以下标志：--target=x86_64-w64-windows-gnu。或者，如果为x32位而不是x64编译，则将x86_64替换为i686。

或者，卸载您的Clang (以及MinGW )并从MSYS2重新安装它们。默认情况下，他们的Clang构建使用此标志。另外，他们提供的GCC的版本比你的更近(10.3比7.3)。

而且，从-stdlib=libc++的角度来看，您正在尝试在Windows上使用libc++。我不认为官方的Clang构建为Windows提供了它，但是MSYS2的人提供了。