For the records: taking a look at core/src/matrix.cpp it seems that, indeed, the constructor cv::Mat(IplImage*)
has disappeared.
But I found this alternative:
IplImage * ipl = ...;
cv::Mat m = cv::cvarrToMat(ipl); // default additional arguments: don't copy data.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…