GCC 15 warns -Wmaybe-uninitialized on text and wechat_qrcode module

[Kumataro]

System Information

OpenCV version: 4.x (4.12.0-192-gedfa999b93)
OpenCV contrib version: 4.x (4.12.0-30-g01fd98d5)
Operating System Platform: Ubuntu 25.10(daily build too)
Compiler & compiler version: GCC 15.2.0

Detailed description

When building with GCC15, there are many warnings about -Wmaybe-uninitialized

/home/kmtr/work/opencv_contrib/modules/text/src/erfilter.cpp:1928:31: warning: ‘dist’ may be used uninitialized [-Wmaybe-uninitialized]
 1928 |         return (this->*distfn)(i,j);


/home/kmtr/work/opencv_contrib/modules/text/src/ocr_hmm_decoder.cpp:459:17: note: ‘last_one_idx’ was declared here
  459 |             int last_one_idx;


/home/kmtr/work/opencv_contrib/modules/wechat_qrcode/src/zxing/common/bytematrix.cpp:36:13: warning: ‘*this.zxing::ByteMatrix::bytes’ may be used uninitialized [-Wmaybe-uninitialized]
   36 |     memcpy(&bytes[0], &source[0], size);

Steps to reproduce

cmake -DCMAKE_CXX_COMPILER=/usr/bin/g++-15 -DCMAKE_C_COMPILER=/usr/bin/gcc-15 -S opencv -DOPENCV_EXTRA_MODULES_PATH=opencv_contrib -B build4-full
cmake --build build4-full