clang++找不到iostream

Question

下面是一个简单的代码：

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main()
{
    std::cout << "Hello, world!" << std::endl;
    return 0;
}

当我想用g++编译它时，没有问题：

$ g++ test.cpp 
$ ./a.out 
Hello, world!

但是，如果我想用clang++来做这件事，它就不再起作用了：

$ clang++ t.cpp               
t.cpp:1:10: fatal error: 'iostream' file not found
#include 
         ^~~~~~~~~~
1 error generated.

如果我添加-v选项，下面是返回clang的内容：

$ clang++ test.cpp -v
Ubuntu clang version 14.0.0-1ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64
Found CUDA installation: /usr/local/cuda, version 
 "/usr/lib/llvm-14/bin/clang" -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name test.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -mllvm -treat-scalable-fixed-error-as-warning -debugger-tuning=gdb -v -fcoverage-compilation-dir=/home/saigre/Bureau -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++ -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/x86_64-linux-gnu -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fdebug-compilation-dir=/home/saigre/Bureau -ferror-limit 19 -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/test-e9d03e.o -x c++ test.cpp
clang -cc1 version 14.0.0 based upon LLVM 14.0.0 default target x86_64-pc-linux-gnu
ignoring nonexistent directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/backward"
ignoring nonexistent directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++
 /usr/lib/llvm-14/lib/clang/14.0.0/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
test.cpp:1:10: fatal error: 'iostream' file not found
#include 
         ^~~~~~~~~~
1 error generated.

这个问题似乎与这个职位完全相同，但我无法从它那里找到解决方案。我还找到了提出这个解决方案的本题

clang++ -I/usr/include/c++/11 -I/usr/include/x86_64-linux-gnu/c++/11 -L /usr/lib/gcc/x86_64-linux-gnu/11 test.cpp

工作得很好。但是我有一个应用程序，在它的执行过程中，它使用clang编译一个小的cpp脚本，而且我对可以传递给它的选项没有任何帮助。

是否有一种方法可以修复clang的配置，这样命令clang++ test.cpp就可以工作，而无需添加任何选项？(过去确实起作用了)

我用的是ubuntu 22.04和gcc-12。

Answer 1

我和一位同事谈过，他告诉我，gcc-12被列入了“ubuntu 22.04”，这给clang造成了一些混乱。为了解决这个问题，我做了

sudo apt install g++-12

现在效果很好。