[SOLVED] Why can't the compiler convert to bool implicitly from sp<android::MetaData>?

Why can't the compiler convert to bool implicitly from sp<android::MetaData>?

I am trying to compile ffmpeg with libstagefright using NDK. I am getting the following error on the compilation of libstagefright.cpp:

libavcodec/libstagefright.cpp: In function 'int Stagefright_init(AVCodecContext*)':
libavcodec/libstagefright.cpp:283:9: error: no match for 'operator!' (operand type is 'android::sp<android::MetaData>')
 if (!meta) {
     ^
libavcodec/libstagefright.cpp:283:9: note: candidate is:
libavcodec/libstagefright.cpp:283:9: note: operator!(bool) <built-in>
libavcodec/libstagefright.cpp:283:9: note:   no known conversion for argument 1 from 'android::sp<android::MetaData>' to 'bool'
make: *** [libavcodec/libstagefright.o] Error 1

The code for the relevant section of libstagefright.cpp is:

meta = new MetaData;
    if (!meta) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }
    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);
    meta->setInt32(kKeyWidth, avctx->width);
    meta->setInt32(kKeyHeight, avctx->height);
    meta->setData(kKeyAVCC, kTypeAVCC, avctx->extradata, avctx->extradata_size);

I am using NDK r10e-rc4 (64-bit) and Ubuntu 14 64 bit

Can somebody please guide as to why this error is occurring, what am i doing wrong?

Solution

In order for compiler to write code for

if (!meta)

android::sp class has to either have operator!() defined, or there has to be a way for this class to be converted to bool, i.e. operator bool(). Since you can't change android::sp implementation, you'll need to find another way to write that. I assume this should work:

if (meta != NULL)