未定义对现有方法的引用

Question

I am trying to compile CyanogenMod 10.2 for my device, but I get a compilation error while compiling frameworks/av:

target SharedLib: libmediaplayerservice (/home/vektor/CM102/out/target/product/s7300b  /obj/SHARED_LIBRARIES/libmediaplayerservice_intermediates/LINKED/libmediaplayerservice.so)
frameworks/av/media/libmediaplayerservice/AmlogicPlayer.cpp:891: error: undefined reference to 'ammodule_match_check(char const*, char const*)'

That method is declared in ammodule.h contained in /device/my/device/packages/LibPlayer/amavutils/include

And in AmlogicPlayer.cpp it's included:

#include "ammodule.h"

In Android.mk the file seems included:

AMPLAYER_APK_DIR=$(TOP)/device/my/device/packages/LibPlayer/
LOCAL_C_INCLUDES +=\
    $(AMPLAYER_APK_DIR)/amavutils/include     

This is the signature from ammodule.h

int ammodule_match_check(const char *allmodstr,const char *modname);

Everything seems ok. What could cause such errors?

Answer 1

The function signiture refers to

const char *

Whereas the c++ file is looking for a function with

char const*

These are not the same thing. One is a constant pointer to a non-constant char, whereas the other is a non-constant pointer to a constant char. Google const char* vs char const* for more info.

Answer 2

This problem is not caused by const char* and char const * because they are all the same. const char * and char * const are different things. Further more, if the signature mis-matches, the compiler, instead of the linker will complain.

I suggest that you check the LD_LIBRARY_PATH and the -l option in your Android.mk to see if the error disappears.