Clang compilation warnings

[yousry]

libtool: compile:  clang++ -DHAVE_CONFIG_H -I. -I../config -I/Users/yousry/Xcode/IOS/root_armv7/include/OpenEXR -I.. -I../config -pipe -g -O2 -MT ImfDwaCompressor.lo -MD -MP -MF .deps/ImfDwaCompressor.Tpo -c ImfDwaCompressor.cpp -o ImfDwaCompressor.o
ImfDwaCompressor.cpp:2386:33: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
    if (unknownUncompressedSize < 0  || 
        ~~~~~~~~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2387:31: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        unknownCompressedSize < 0    ||
        ~~~~~~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2388:26: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        acCompressedSize < 0         || 
        ~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2389:26: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        dcCompressedSize < 0         ||
        ~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2390:27: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        rleCompressedSize < 0        || 
        ~~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2391:29: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        rleUncompressedSize < 0      ||
        ~~~~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2392:20: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        rleRawSize < 0               ||  
        ~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2393:34: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        totalAcUncompressedCount < 0 || 
        ~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2394:34: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        totalDcUncompressedCount < 0) 
        ~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2485:18: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
    if ((version < 0) || (version > 2))
         ~~~~~~~ ^ ~
ImfDwaCompressor.cpp:2499:37: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        if (unknownUncompressedSize < 0 || 
            ~~~~~~~~~~~~~~~~~~~~~~~ ^ ~
11 warnings generated.

and

libtool: compile:  clang++ -DHAVE_CONFIG_H -I. -I../config -I/Users/yousry/Xcode/IOS/root_armv7/include/OpenEXR -I.. -I../config -pipe -g -O2 -MT ImfScanLineInputFile.lo -MD -MP -MF .deps/ImfScanLineInputFile.Tpo -c ImfScanLineInputFile.cpp -o ImfScanLineInputFile.o
ImfScanLineInputFile.cpp:1408:22: warning: enumeration value 'NUM_PIXELTYPES' not handled in switch [-Wswitch]
              switch(i.channel().type)
                     ^
ImfScanLineInputFile.cpp:1478:22: warning: enumeration value 'NUM_PIXELTYPES' not handled in switch [-Wswitch]
              switch(i.channel().type)
                     ^
2 warnings generated.

[meshula]

The "not handled" warnings are in the annoying nanny category.

The signed comparison warnings should be addressed, the compressedSize variables are intended to be negative as an error condition, their type should be ssize_t.

[CAHEK7]

Signed comparison warnings happened due to confusing Int64 typedef declared in IlmBase/Imath/ImathInt64.h. Int64 declared as unsigned.

I would suggest to make it signed and define UInt64 as unsigned. If there are no strong objections I can do the changes. Also I can check another signed-unsigned issues, there are bunch of it if you turn on -Wsign-compare in gcc.

[meshula]

Good catch! ImathInt64 uses tricks that are no longer necessary; there is no longer a need to specialize per compiler.. If you make the change, please use <cstdint> and define the types as

typedef int64_t Int64;

[CAHEK7]

Have dug deeper and found out that a lot of code relies on Int64 unsigned nature and only some cases treat it as signed. And there are a lot of code which mixing signed and unsigned values. Proper fixing requires deep analysis and massive changes, but this particular case can be covered.
Also <cstdint> officially is C++11 feature, it can break portability (though it's supported by most compilers).

[meshula]

Should probably open another issue with your findings if you wouldn't mind. The ad hoc treatment of signed/unsigned is undesirable.

[kdt3rd]

The code base in master now compiles cleanly with gcc 9 and clang 8 using -Wall