<h5 dir="auto">System information (version)</h5>
<ul dir="auto">
<li>OpenCV 4.5.4</li>
<li>Python 3.7 (opencv installed using pip: "pip install opencv-python")</li>
<li>Ubuntu 18.04 amd64</li>
</ul>
<h5 dir="auto">Detailed description</h5>
<p dir="auto">Up to version 4.5.3 findContours returned contours as a list. Starting on version 4.5.4 the contours are returned as a tuple. This will break codes that try to modify the returned tuple.</p>
<h5 dir="auto">Steps to reproduce</h5>
<p dir="auto">contours, hierarchy = cv2.findContours(binary_image, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_SIMPLE)<br>
for i in range(len(contours)):<br>
contours[i] = np.round(contours[i]*[1/3, -1/3]).astype(np.int32)</p>
<h5 dir="auto">System information (version)</h5>

<ul dir="auto">
<li>OpenCV =&gt; 3.4, master</li>
<li>Operating System / Platform =&gt; all</li>
<li>Compiler =&gt; gcc-10</li>
</ul>
<h5 dir="auto">Detailed description</h5>
<div class="highlight highlight-source-shell notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_iterator.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_operations.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_sparse.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_wrap.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/mean.dispatch.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/merge.dispatch.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/minmax.cpp.o
"><pre class="notranslate">[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_iterator.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_operations.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_sparse.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/matrix_wrap.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/mean.dispatch.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/merge.dispatch.cpp.o
cc1plus: warning: command-line option ‘-Wmissing-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid <span class="pl-k">for</span> C/ObjC but not <span class="pl-k">for</span> C++
[ 30%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/minmax.cpp.o
</pre></div>
<h4 dir="auto">3rdparty warnings (C sources)</h4>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="cc1plus: warning: command-line option ‘-Wno-missing-prototypes’ is valid for C/ObjC but not for C++
[  8%] Building CXX object 3rdparty/openexr/CMakeFiles/IlmImf.dir/Half/half.cpp.o
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wno-missing-prototypes’ is valid for C/ObjC but not for C++
[  8%] Building C object 3rdparty/libtiff/CMakeFiles/libtiff.dir/tif_dirwrite.c.o
[  8%] Building C object 3rdparty/libjasper/CMakeFiles/libjasper.dir/jpc_enc.c.o
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for C
[  8%] Building C object 3rdparty/libjpeg-turbo/CMakeFiles/libjpeg-turbo.dir/src/jdatasrc.c.o
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for C
[  8%] Building C object 3rdparty/libjpeg-turbo/CMakeFiles/libjpeg-turbo.dir/src/jdcoefct.c.o
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for "><pre class="notranslate"><code class="notranslate">cc1plus: warning: command-line option ‘-Wno-missing-prototypes’ is valid for C/ObjC but not for C++
[  8%] Building CXX object 3rdparty/openexr/CMakeFiles/IlmImf.dir/Half/half.cpp.o
cc1plus: warning: command-line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command-line option ‘-Wno-missing-prototypes’ is valid for C/ObjC but not for C++
[  8%] Building C object 3rdparty/libtiff/CMakeFiles/libtiff.dir/tif_dirwrite.c.o
[  8%] Building C object 3rdparty/libjasper/CMakeFiles/libjasper.dir/jpc_enc.c.o
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for C
[  8%] Building C object 3rdparty/libjpeg-turbo/CMakeFiles/libjpeg-turbo.dir/src/jdatasrc.c.o
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for C
[  8%] Building C object 3rdparty/libjpeg-turbo/CMakeFiles/libjpeg-turbo.dir/src/jdcoefct.c.o
cc1: warning: command-line option ‘-Wsign-promo’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wsuggest-override’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-Wno-delete-non-virtual-dtor’ is valid for C++/ObjC++ but not for C
cc1: warning: command-line option ‘-fvisibility-inlines-hidden’ is valid for C++/ObjC++ but not for 
</code></pre></div>
<h5 dir="auto">Steps to reproduce</h5>
<p dir="auto">build OpenCV on GCC 10</p>