使用-O0时，g ++停止未定义的引用 [英] g++ stops on undefined reference when using -O0

问题描述

我想调试我写的程序。因此，我想使用-g -O0链接。当我编译（使用autotools Makefile）使用

I want to debug a program I wrote. Therefor I'd like to link it using "-g -O0". When I compile (using autotools Makefile) using

make CXXFLAGS =' - g -O0'

make CXXFLAGS='-g -O0'

我得到一些错误：

libtool：link：g ++ -O2 -g - O0-I / opt / adolc-2.2.1 / include -o oc_poly oc_poly-oc_poly.o
oc_poly-oc_p2p.o -L / opt / ipopt-3.9.3 / lib / coin -L / opt / ipopt -3.9.3 / lib / coin / ThirdParty
-L ​​/ usr / lib / i386-linux-gnu / gcc / i686-linux-gnu / 4.5.2 -L / usr / lib / i386-linux-gnu / gcc / i686-
linux-gnu / 4.5.2 /../../... -L / usr / lib / i386-linux-gnu /opt/ipopt-3.9.3/lib/coin/ libipopt.so
-llapack -ldl /opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinhsl.so /opt/ipopt-3.9.3/lib
/ coin / ThirdParty / libcoinblas。所以/opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinlapack.so
/opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinmumps.so -lpthread -lblas -lgfortran -lm
-lgcc_s /opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinmetis.so -L / opt / adolc-2.2.1 / lib
/opt/adolc-2.2.1/lib/ libadolc.so -Wl，-rpath -Wl，/ opt / ipopt-3.9.3 / lib / coin -Wl，-rpath
-Wl，/ opt / ipopt-3.9.3 / lib / coin / ThirdParty - wl，-rpath -Wl，/ opt / adolc-2.2.1 / lib -Wl，-rpath
-W1，/ opt / ipopt-3.9.3 / lib / coin -Wl，-rpath -Wl， opt / ipopt-3.9.3 / lib / coin / ThirdParty
-Wl，-rpath -Wl，/ opt / adolc-2.2.1 / lib
oc_poly-oc_p2p.o：In function OCP_P2P :: get_bounds_info（int，double *，double *，int，
double *，double *）'：
/ home / christian / Dokumente / Uni / SA / ist / Berechnungen / Optimale Steuernug / IpOpt
/oc_p2p.cpp:162：未定义引用 OCP_P2P :: INF'

libtool: link: g++ -O2 -g -O0 -I/opt/adolc-2.2.1/include -o oc_poly oc_poly-oc_poly.o oc_poly-oc_p2p.o -L/opt/ipopt-3.9.3/lib/coin -L/opt/ipopt-3.9.3/lib/coin/ThirdParty -L/usr/lib/i386-linux-gnu/gcc/i686-linux-gnu/4.5.2 -L/usr/lib/i386-linux-gnu/gcc/i686- linux-gnu/4.5.2/../../.. -L/usr/lib/i386-linux-gnu /opt/ipopt-3.9.3/lib/coin/libipopt.so -llapack -ldl /opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinhsl.so /opt/ipopt-3.9.3/lib /coin/ThirdParty/libcoinblas.so /opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinlapack.so /opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinmumps.so -lpthread -lblas -lgfortran -lm -lgcc_s /opt/ipopt-3.9.3/lib/coin/ThirdParty/libcoinmetis.so -L/opt/adolc-2.2.1/lib /opt/adolc-2.2.1/lib/libadolc.so -Wl,-rpath -Wl,/opt/ipopt-3.9.3/lib/coin -Wl,-rpath -Wl,/opt/ipopt-3.9.3/lib/coin/ThirdParty -Wl,-rpath -Wl,/opt/adolc-2.2.1/lib -Wl,-rpath -Wl,/opt/ipopt-3.9.3/lib/coin -Wl,-rpath -Wl,/opt/ipopt-3.9.3/lib/coin/ThirdParty -Wl,-rpath -Wl,/opt/adolc-2.2.1/lib oc_poly-oc_p2p.o: In function OCP_P2P::get_bounds_info(int, double*, double*, int, double*, double*)': /home/christian/Dokumente/Uni/SA/ist/Berechnungen/Optimale Steuernug/IpOpt /oc_p2p.cpp:162: undefined reference toOCP_P2P::INF'

所提到的符号INF是在类定义OCP_P2P中定义的静态类成员。

The mentioned symbol INF is a static class member defined in the class definition OCP_P2P.

如果省略CXXFLAGS或将它们设置为O1， O3或Os，链接工作得很好。我使用g ++ 4.5.2。

If I omit the CXXFLAGS or set them to any optimization value of O1, O2, O3 or Os the linking works pretty well. I am using g++ 4.5.2.

任何人都可以给我一个提示，这里出了什么问题？如何调试我的程序？

Can anybody give me a hint, what's going wrong here? How can I debug my program?

感谢

Christian

Christian

推荐答案

静态类成员变量需要定义;即使它在类定义中仅初始化为一个声明。换句话说，你需要把

A static class member variable needs a definition; even if it is initialised in the class definition that is only a declaration. In other words, you need to put

const double OCP_P2P::INF;

在cpp文件中的某处。假设当优化被打开时，变量的使用被优化。

somewhere in a cpp file. Presumably when optimisation was turned on the use of the variable was optimised out.

官方规则是，如果变量是，则需要一个定义，根据标准的 used 定义，这基本上是指向变量的指针，或者变量绑定到引用。

The official rule is that a definition is needed if the variable is used, according to the standard's definition of used, which is basically if a pointer to the variable is taken, or if the variable is bound to a reference.

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