未定义的符号_main在尝试构建共享库时使用g ++ / mac [英] Undefined symbol _main when trying to build shared library g++ / mac

问题描述

我正在试图在Mac上构建libdecodeqr。我的c ++构建和链接历史都在windows上，所以这是一个令人兴奋的发现之旅。

我终于到了想要创建链接库的地步。我正在运行的命令是：

  g ++ -shared -o libdecodeqr.so.0.9.3 bitstream.o codedata.o容器.o ecidecoder.o formatinfo.o galois.o imagereader.o libdecodeqr.o -L / opt / local / lib -arch i386 -lcxcore -lcv 
  

结果是：

$ p $ 未定义符号：
_main，引用自：
开始于crt1.10.5.o


我的印象是，使用-shared标志创建一个库意味着我不应该需要一个主要功能。在源代码中肯定没有一个。

只是为了踢我添加int main（）{返回0;}到其中一个cpp文件并重建。整个事情编译和链接，但是当我试图使用输出作为库时，我得到错误告诉我，我不能链接到一个主要的可执行文件。这是有道理的我猜。

有什么我需要传递给g ++来告诉它建立一个库吗？

解决方案

-shared 在OSX上不受支持。使用 -dynamiclib 或 -bundle （具体取决于您要创建哪种类型的共享库）。

I am trying to build libdecodeqr on a mac. My c++ building and linking history is all on windows, so it's an exciting journey of discovery.

I have finally got to the point where I want to create the linked library. The command I am running is:

g++ -shared -o libdecodeqr.so.0.9.3 bitstream.o codedata.o container.o ecidecoder.o formatinfo.o galois.o imagereader.o libdecodeqr.o -L/opt/local/lib -arch i386 -lcxcore -lcv

The result is:

Undefined symbols:
    "_main", referenced from:
       start in crt1.10.5.o

I was under the impression that a creating a library using -shared flag meant I shouldn't need a main function. There certainly isn't one in the source code.

Just for kicks I added int main() {return 0;} to one of the cpp files and rebuilt. The whole thing compiled and linked, but when I tried to use the output as a library I got errors telling me that I can't link to a main executable. That makes sense I guess.

Is there something else I need to pass to g++ to tell it to build a library?

解决方案

-shared is not supported on OSX. Use either -dynamiclib or -bundle (depending on which type of shared library you want to create).

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