clang似乎没有链接到库

clang appears not to be linking to a library

本文关键字：链接 clang      更新时间：2023-10-16

我将问题归结为以下示例：

int main()
{
    try {
        throw false;
    } catch (bool x)
    {
        if (x)
        {
            return 0;
        }
        else
        {
            return 1;
        }
    }
}

在Coliru上生成以下错误：

/tmp/main-c8b47a.o: In function `main':
main.cpp:(.text+0xf): undefined reference to `typeinfo for bool'
/tmp/main-c8b47a.o: In function `GCC_except_table0':
main.cpp:(.gcc_except_table+0x30): undefined reference to `typeinfo for bool'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

命令行：

clang++-std=c++11-stdlib=libc++-O2-墙-迂腐-pthread main.cpp&amp/a.out

这听起来像是没有链接到库。有人知道命令行开关是什么吗？我以前没用过叮当声。这在g++下工作。

这是带有-v开关的输出：

clang version 3.6.0 (tags/RELEASE_360/final 235480)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.2
Found candidate GCC installation: /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.8.2
Found candidate GCC installation: /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.9.0
Found candidate GCC installation: /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.9.2
Found candidate GCC installation: /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.1.0
Found candidate GCC installation: /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0
Selected GCC installation: /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "/usr/local/bin/clang" -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -disable-free -disable-llvm-verifier -main-file-name main.cpp -mrelocation-model static -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -target-linker-version 2.22 -momit-leaf-frame-pointer -v -dwarf-column-info -resource-dir /usr/local/bin/../lib/clang/3.6.0 -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/include -internal-isystem /usr/local/bin/../lib/clang/3.6.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wall -pedantic -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /tmp/1441759762.34715 -ferror-limit 19 -fmessage-length 0 -pthread -mstackrealign -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -vectorize-loops -vectorize-slp -o /tmp/main-47c098.o -x c++ main.cpp
clang -cc1 version 3.6.0 based upon LLVM 3.6.0 default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/c++/v1
 /usr/local/include
 /usr/local/bin/../lib/clang/3.6.0/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
 "/usr/bin/ld" --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/lib/x86_64-linux-gnu/crt1.o /usr/lib/x86_64-linux-gnu/crti.o /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0/crtbegin.o -L/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0 -L/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0/../../../../lib64 -L/usr/local/bin/../lib64 -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0/../../.. -L/usr/local/bin/../lib -L/lib -L/usr/lib /tmp/main-47c098.o -lc++ -lm -lgcc_s -lgcc -lpthread -lc -lgcc_s -lgcc /usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.2.0/crtend.o /usr/lib/x86_64-linux-gnu/crtn.o
/tmp/main-47c098.o: In function `main':
main.cpp:(.text+0xf): undefined reference to `typeinfo for bool'
/tmp/main-47c098.o: In function `GCC_except_table0':
main.cpp:(.gcc_except_table+0x30): undefined reference to `typeinfo for bool'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

看起来您需要在main.cpp之后添加-lsupc++(实时查看(：

clang++ -std=c++11  -stdlib=libc++ -O2 -Wall -pedantic -pthread main.cpp -lsupc++
                                                                         ^^^^^^^^

正如Andre Kostur所指出的，libc++文档建议如下，尽管我似乎无法在Coliru上实现这一点：

不幸的是，在这种情况下，您不能简单地使用"-stdlib=libc++"运行clang点，因为clang被设置为链接到libsupc++的libc++。到绕过这个问题，你必须自己设置链接器(或补丁叮当声(。例如，

  • clang++-stdlib=libc++helloworld.cpp-nodefaultlibs-lc++-lcxrt-lm-lc-lgcc_s-lgcc

或者，您可以将libcxxrt添加到库列表中在大多数情况下都会给出相同的结果：

  • clang++-stdlib=libc++helloworld.cpp-lcxrt

这似乎与本线程中讨论的问题有关，使Linux上的libc++用户友好，并在下面选择性引用：

问题是：当构建libc++时，链接器会发现ABI在libstdc++中起作用，并且很高兴它们在那里。然而，当Clang为实际程序调用链接器时，它不会为libstdc++传递一个链接标志，仅为libc++传递。因此失败。

和：

这也可以通过显式指定针对源库的链接来解决，在这里-lsupc++是有效的。

另请参阅Linux等效的Windows DLL转发器或MacOS再导出库。

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