Some compiler warnings when compiling under Windows with Microsoft Visual C++

[ghost]

Hi,

I'm having some compiler warning from CImg code when loading jpeg or png images under Windows 10 with Visual Studio 2019. These warnings don't pop-up when I do a posix build with GCC or Clang of the same project. The build log from a windows build:

CImg.h(61221,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61122): message : while compiling class template member function 'cimg_library::CImgList<unsigned char> &cimg_library::CImgList<unsigned char>::_load_cimg(FILE *const ,const char *const )' CImg.h(61101): message : see reference to function template instantiation 'cimg_library::CImgList<unsigned char> &cimg_library::CImgList<unsigned char>::_load_cimg(FILE *const ,const char *const )' being compiled CImg.h(53306): message : see reference to class template instantiation 'cimg_library::CImgList<unsigned char>' being compiled CImg.h(53305): message : while compiling class template member function 'cimg_library::CImg<unsigned char> &cimg_library::CImg<unsigned char>::load_cimg(const char *const ,const char,const float)' CImg.h(54847): message : see reference to function template instantiation 'cimg_library::CImg<unsigned char> &cimg_library::CImg<unsigned char>::load_cimg(const char *const ,const char,const float)' being compiled CImg.h(64756): message : see reference to class template instantiation 'cimg_library::CImg<unsigned char>' being compiled CImg.h(61222,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61223,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61224,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61225,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61226,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61227,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61228,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61229,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61230,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61231,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61232,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg\CImg.h(61233,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg\CImg.h(61234,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg\CImg.h(61235,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg\CImg.h(61236,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg\CImg.h(61237,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61238,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data

I'm not sure if this is just some microsoft specific compiler warning but not really a bug. It started popping up a couple of months ago, before I didn't have this warnings from the same code.

Thanks!

[dtschump]

Could you please copy/paste the line in CImg.h that trigger this warning ? Is it

      const ulongT cimg_iobuffer = (ulongT)24*1024*1024;

?

If so, on which kind of architecture are you using CImg ? 32bits or 64bits ?

Thanks.

[ghost]

Hi,

I'm compiling for x64. It's triggerd on line 61221 (a bit below the line you gave)

`
61221 _cimg_load_cimg_case("bool",bool);

61222 _cimg_load_cimg_case("unsigned_char",unsigned char); 61223 _cimg_load_cimg_case("uchar",unsigned char); 61224 _cimg_load_cimg_case("char",char); 61225 _cimg_load_cimg_case("unsigned_short",unsigned short); 61226 _cimg_load_cimg_case("ushort",unsigned short); 61227 _cimg_load_cimg_case("short",short); 61228 _cimg_load_cimg_case("unsigned_int",unsigned int); 61229 _cimg_load_cimg_case("uint",unsigned int); 61230 _cimg_load_cimg_case("int",int); 61231 _cimg_load_cimg_case("unsigned_long",ulongT); 61232 _cimg_load_cimg_case("ulong",ulongT); 61233 _cimg_load_cimg_case("long",longT); 61234 _cimg_load_cimg_case("unsigned_int64",uint64T); 61235 _cimg_load_cimg_case("uint64",uint64T); 61236 _cimg_load_cimg_case("int64",int64T); 61237 _cimg_load_cimg_case("float",float); 61238 _cimg_load_cimg_case("double",double); `

[dtschump]

Thanks. I'll check that and try to remove that warning.

[ghost]

Thanks a lot!

[dtschump]

Just a question : have you tried with the very latest CImg file, available at https://raw.githubusercontent.com/dtschump/CImg/develop/CImg.h ? It may have been already corrected (it seems I had something similar a few weeks ago).

[ghost]

Yes, it happens on the very latest CImg.h file also. I use CImg as a submodule in github and do a regulary update. But I've rechecked with the file you provided and the same thing happens.

[dtschump]

OK, thanks. I'm compiling it right now with Visual Studio 2019 (but from the command line), and it seems I don't get those errors. There is maybe a specific flag to activate.

[dtschump]

Maybe, did you activate the cimg_use_zlib macro when compiling your code ?

[ghost]

I use cimg_use_cpp11 cimg_use_openmp cimg_use_jpeg cimg_use_png cimg_use_zlib

The compile flags are using the default /W3 flag Obviously when I lower this to /W2 and do a rebuild all those warnings indeed go away But the Microsoft default flag is /W3 as WarningLevel

[dtschump]

OK, thanks, that definitely helps. Still investigating...

[ghost]

In the latest CImg.h code the issue start at line number: 61227 _cimg_load_cimg_case("bool",bool);

[dtschump]

Could you please try this : https://github.com/dtschump/CImg/commit/9a95c05805e59a4f0a65a2148a3217a9576bf891 ?

[ghost]

Build log with 9a95c05https://github.com/dtschump/CImg/commit/9a95c05805e59a4f0a65a2148a3217a9576bf891

CImg.h(61227,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data

CImg.h(61128): message : while compiling class template member function 'cimg_library::CImgList &cimg_library::CImgList::_load_cimg(FILE const ,const char const )'

CImg.h(61107): message : see reference to function template instantiation 'cimg_library::CImgList &cimg_library::CImgList::_load_cimg(FILE const ,const char const )' being compiled

CImg.h(53312): message : see reference to class template instantiation 'cimg_library::CImgList' being compiled

CImg.h(53311): message : while compiling class template member function 'cimg_library::CImg &cimg_library::CImg::load_cimg(const char *const ,const char,const float)'

CImg.h(54853): message : see reference to function template instantiation 'cimg_library::CImg &cimg_library::CImg::load_cimg(const char *const ,const char,const float)' being compiled

CImg.h(64762): message : see reference to class template instantiation 'cimg_library::CImg' being compiled CImg.h(61228,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61229,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61230,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61231,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61232,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61233,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61234,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61235,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61236,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61237,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61238,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61239,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61240,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61241,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61242,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61243,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data CImg.h(61244,7): warning C4267: 'argument': conversion from 'size_t' to 'const unsigned int', possible loss of data

[dtschump]

Well, here is my last attempt for today: https://github.com/dtschump/CImg/commit/766163fb864317aa9c65e5711e96fe7550011595 I don't think this will solve the problem anyway. It's hard, because I have to guess what is going on without being able to reproduce the warnings here on my VM.

[ghost]

No, with https://github.com/dtschump/CImg/commit/766163fb864317aa9c65e5711e96fe7550011595 gives me the exact same warnings as the previous build. If you should have some time at a some later point obvious no problem. It's not some urgent serious bug

Thanks a lot

[dtschump]

Hello, back in the business :) I'd be actually interested by all the flags set by your compilation command, to reproduce the problem on my machine (then fix it more easily). Could you please copy/paste the set of flags used to trigger the warning? Thanks a lot!

[ghost]

Hi,

Sorry for the late response. I'm just awake.

for a Release build: (the warnings happens in a Debug build too) compile flags: /MP /ifcOutput "x64\Release\" /GS /GL /analyze- /W3 /Gy /Zc:wchar_t /I"dnn\deps\magic_enum\include" /I"C:\Users\dhaen\source\repos\convnet\dnn\include" /I"C:\Users\dhaen\source\repos\convnet\deps\vectorclass" /I"C:\Users\dhaen\source\repos\convnet\dnn\deps\libpng" /I"C:\Users\dhaen\source\repos\convnet\dnn\deps\libjpeg-turbo" /I"C:\Users\dhaen\source\repos\convnet\dnn\deps\oneDNN\include" /I"C:\Users\dhaen\source\repos\convnet\dnn\deps\oneDNN\build\include" /Gm- /O2 /Ob2 /Fd"x64\Release\vc142.pdb" /Zc:inline /fp:fast /D "DNN_EXPORTS" /D "DNN_DLL" /D "NDEBUG" /D "WIN32" /D "DNN_OMP" /D "DNN_CACHE_PRIMITIVES" /D "DNN_AVX2" /D "cimg_use_cpp11" /D "cimg_use_openmp" /D "cimg_use_jpeg" /D "cimg_use_png" /D "cimg_use_zlib" /D "_WINDOWS" /D "_USRDLL" /D "_WINDLL" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /GF /WX- /Zc:forScope /GR /arch:AVX2 /Gd /Oi /MD /std:c++17 /FC /Fa"x64\Release\" /EHsc /Fo"x64\Release\" /Ot /Fp"x64\Release\dnn.pch" /diagnostics:column

linker flags: /OUT:"C:\Users\dhaen\source\repos\convnet\x64\Release\dnn.dll" /MANIFEST /LTCG /NXCOMPAT /PDB:"C:\Users\dhaen\source\repos\convnet\x64\Release\dnn.pdb" /DYNAMICBASE "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "comdlg32.lib" "advapi32.lib" /IMPLIB:"C:\Users\dhaen\source\repos\convnet\x64\Release\dnn.lib" /DLL /MACHINE:X64 /OPT:REF /PGD:"C:\Users\dhaen\source\repos\convnet\x64\Release\dnn.pgd" /SUBSYSTEM:WINDOWS /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /ManifestFile:"x64\Release\dnn.dll.intermediate.manifest" /LTCGOUT:"x64\Release\dnn.iobj" /OPT:ICF /ERRORREPORT:PROMPT /NOLOGO /TLBID:1

[dtschump]

Well, just tried and many options seem to be not recognized by my version of the compiler (apparently it's cl 19.22.27905). At this point, I guess I need to update my version of VS2019 before trying anything else.

Won't have much time for that the next days, but I'll keep it in my todo list. Thanks again.

[ghost]

Ok

Thanks for your time!

[dtschump]

OK, some news:

• I've spent some time tonight to update my version of Visual Studio 2019 (installed the Community Edition).
• With it, I got the same warnings that you have.
• Commit https://github.com/dtschump/CImg/commit/29ab0faff7a2093b244f9cac043b3fa7a8689a50 should fix the issue (it does for me).

[ghost]

That's fantastic news! :)

When I use https://github.com/dtschump/CImg/commit/29ab0faff7a2093b244f9cac043b3fa7a8689a50 all warnings are indeed all gone!

Does this fix also comes to the master branch after some time or do I have to switch to the develop branch for the latest fixes instead?

Thanks a lot for fixing this issue!

[dtschump]

I've pushed the current develop version to master, so it should be OK now. Thanks again for helping me solving this.