c++ - 允许共享库中 undefined reference 的 g++ 标志是什么？

Question

我记得我曾在互联网上的某个时候准确地读过这个标志是什么，但现在我忘记了。

我正在编写一个共享库，我希望我的库允许 undefined reference 。这样，无论谁使用我的库，都必须链接到它和链接到它的依赖项。 g++ 上的什么标志允许这样做？或者它可能是一个链接器标志？

Answer 1

这只能是一个链接器标志...然后，它取决于您使用的链接器。
在 Linux 上(可能还有 BSD，至少是 FreeBSD )这应该是默认行为。不过在 Mac 上不行。

来自GNU ld man page :

--allow-shlib-undefined
--no-allow-shlib-undefined
          Allows or disallows undefined symbols in shared libraries.
          This switch is similar to --no-undefined except that it determines
          the behaviour when the undefined symbols are in a shared library rather
          than a regular object file. It does not affect how undefined symbols in
          regular object files are handled.

          The default behaviour is to report errors for any undefined symbols
          referenced in shared libraries if the linker is being used to create an
          executable, but to allow them if the linker is being used to create a
          shared library.

来自Apple ld man page :

-undefined treatment  
         Specifies how undefined symbols are to be treated. Options
         are: error, warning, suppress, or dynamic_lookup.  The
         default is error.