使用gcc -l后缺少ldd中的库

Question

我正在编译一个名为"interrogate"的可执行文件:

g++ -o built/bin/interrogate -Lbuilt/lib -Lbuilt/tmp -L/usr/X11R6/lib \
built/tmp/interrogate_composite1.o built/tmp/interrogate_composite2.o \
-lp3cppParser -lp3dtool -lp3dtoolconfig -lp3pystub -pthread -ldl

编译后,当我尝试执行可执行文件时:

$ LD_LIBRARY_PATH=built/lib built/bin/interrogate
built/bin/interrogate: symbol lookup error: built/lib/libp3dtool.so.1.8: undefined symbol: _Py_NoneStruct

此符号由libp3pystub.so提供,但询问可执行文件没有对此库的任何引用(我使用了-lp3pystub):

$ LD_LIBRARY_PATH=built/lib ldd built/bin/interrogate
    linux-vdso.so.1 =>  (0x00007fff2016a000)
    libp3dtool.so.1.8 => built/lib/libp3dtool.so.1.8 (0x00007f498d57a000)
    libp3dtoolconfig.so.1.8 => built/lib/libp3dtoolconfig.so.1.8 (0x00007f498d51b000)
    libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f498d1f2000)
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f498cfdc000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f498cdbf000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f498c9ff000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f498c7fb000)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f498c4ff000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f498d5bc000)

如果我手动加载libp3pystub.so,可执行文件的工作原理:

$ LD_PRELOAD=built/lib/libp3pystub.so LD_LIBRARY_PATH=built/lib built/bin/interrogate

Usage:
  interrogate [opts] file.C [file.C ...]
  interrogate -h

我的问题是:为什么我添加的库-lp3pystub未被interrogate可执行文件引用？

Answer 1

我自己找到了答案.我正在编译Ubuntu,他们添加了一个默认的优化标志:-Wl,--as-needed.此优化检查是否在主可执行文件中使用了带有-l的库中的符号,它们将被删除.

这就是我的错误所在:_Py_NoneStruct不是由询问者直接使用,而是由另一个共享库直接使用.所以我必须手动指定需要p3pystub.

一个可能的解决方案是:

$ g++ -o built/bin/interrogate -Lbuilt/lib -Lbuilt/tmp -L/usr/X11R6/lib \
built/tmp/interrogate_composite1.o built/tmp/interrogate_composite2.o \
-Wl,--no-as-needed -lp3cppParser -lp3dtool -lp3dtoolconfig -lp3pystub \
-pthread -ldl

然后我正确地在ldd输出中获得了库:

$ LD_LIBRARY_PATH=built/lib ldd built/bin/interrogate
    linux-vdso.so.1 =>  (0x00007fff0edff000)
    libp3dtool.so.1.8 => built/lib/libp3dtool.so.1.8 (0x00007fa1c36be000)
    libp3dtoolconfig.so.1.8 => built/lib/libp3dtoolconfig.so.1.8 (0x00007fa1c365f000)
>>> libp3pystub.so.1.8 => built/lib/libp3pystub.so.1.8 (0x00007fa1c3658000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fa1c342f000)
    libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fa1c312c000)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fa1c2e2f000)
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fa1c2c19000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fa1c29fc000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fa1c263c000)
    /lib64/ld-linux-x86-64.so.2 (0x00007fa1c3700000)

参考:https: //wiki.ubuntu.com/NattyNarwhal/ToolchainTransition