Opencv_contrib: got implicit-function-declaration error while compiling iOS framework

[formalin14]

running command:

python opencv/platforms/ios/build_framework.py ios

and got:

error: implicit declaration of function 'read' is invalid in C99 [-Werror,-Wimplicit-function-declaration]

while:

CompileC /Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/Objects-normal/arm64/gzread.o 3rdparty/zlib/gzread.c normal arm64 c com.apple.compilers.llvm.clang.1_0.compiler

whole error message:

CompileC /Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/Objects-normal/arm64/gzread.o 3rdparty/zlib/gzread.c normal arm64 c com.apple.compilers.llvm.clang.1_0.compiler
    cd /Users/formalin14/green/opencv
    export LANG=en_US.US-ASCII
    export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/Users/formalin14/Library/Android/sdk/tools:/Users/formalin14/Library/Android/sdk/platform-tools:/Users/formalin14/.nvm/versions/node/v4.2.2/bin:/usr/local/sbin:/usr/local/mysql/bin:/Users/formalin14/green/mongodb/bin:/Users/formalin14/green/adt-0702/sdk/tools:/Users/formalin14/.rakudobrew/bin:/usr/local/bin:/Users/formalin14/green/android-ndk-r10c:/Users/formalin14/green/cocos2d-js-v3.2-rc0/tools/cocos2d-console/bin:/Users/formalin14/green/android-ndk-r10c:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/usr/local/go/bin:/Users/formalin14/bin/FDK/Tools/osx:/Users/formalin14/dev/go/bin"
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -x c -arch arm64 -fmessage-length=193 -fdiagnostics-show-note-include-stack -fmacro-backtrace-limit=0 -fcolor-diagnostics -Wno-trigraphs -fpascal-strings -O3 -Wno-missing-field-initializers -Wno-missing-prototypes -Wno-return-type -Wno-missing-braces -Wparentheses -Wswitch -Wno-unused-function -Wno-unused-label -Wno-unused-parameter -Wno-unused-variable -Wunused-value -Wno-empty-body -Wno-uninitialized -Wno-unknown-pragmas -Wno-shadow -Wno-four-char-constants -Wno-conversion -Wno-constant-conversion -Wno-int-conversion -Wno-bool-conversion -Wno-enum-conversion -Wshorten-64-to-32 -Wpointer-sign -Wno-newline-eof -DCMAKE_INTDIR=\"Release-iphoneos\" -DNO_FSEEKO -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS9.3.sdk -fstrict-aliasing -Wdeprecated-declarations -miphoneos-version-min=6.0 -Wno-sign-conversion -fembed-bitcode-marker -I/Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/lib/Release/include -I/Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib -I/Users/formalin14/green/opencv/3rdparty/zlib -I/Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS -I/Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/DerivedSources/arm64 -I/Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/DerivedSources -Wmost -Wno-four-char-constants -Wno-unknown-pragmas -F/Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/lib/Release -fembed-bitcode -fPIC -fPIC -DNDEBUG -DNDEBUG -MMD -MT dependencies -MF /Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/Objects-normal/arm64/gzread.d --serialize-diagnostics /Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/Objects-normal/arm64/gzread.dia -c /Users/formalin14/green/opencv/3rdparty/zlib/gzread.c -o /Users/formalin14/green/opencv_ios/build/arm64-iPhoneOS/3rdparty/zlib/OpenCV.build/Release-iphoneos/zlib.build/Objects-normal/arm64/gzread.o
clang: warning: argument unused during compilation: '-fembed-bitcode-marker'
/Users/formalin14/green/opencv/3rdparty/zlib/gzread.c:30:21: error: implicit declaration of function 'read' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        ret = (int) read(state->fd, buf + *have, len - *have);
                    ^
/Users/formalin14/green/opencv/3rdparty/zlib/gzread.c:30:21: note: did you mean 'fread'?
In file included from /Users/formalin14/green/opencv/3rdparty/zlib/gzread.c:6:
In file included from /Users/formalin14/green/opencv/3rdparty/zlib/gzguts.h:21:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS9.3.sdk/usr/include/stdio.h:247:9: note: 'fread' declared here
size_t   fread(void * __restrict, size_t, size_t, FILE * __restrict);

[formalin14]

I manually fixed this by adding

include "unistd.h"

into gzread.c, gzlib.c and gzwrite.c.

Maybe you can fix this by changing clang flags.

[alalek]

https://github.com/Itseez/opencv/issues/6093