Error on Mac OS X 10.7: error: unknown attribute __hot__

[DanKegel]

Building apps that link to ImageMagick 6.8.8-4 on MacOS X 10.7 can fail with the error

In file included from /Users/buildbot/slave-state/osx107/g-speak-rbb-osx107-1/sandbox-osx107-master3_13/build/examples/radiology/radiology.C:26:

• ...
  /opt/oblong/deps-64-9/include/ImageMagick/magick/pixel.h:179:42:
  error: unknown attribute '__hot__' ignored [-Werror,-Wattributes]
  DecodePixelGamma(const MagickRealType) magick_hot_spot,
  ^
  /opt/oblong/deps-64-9/include/ImageMagick/magick/method-attribute.h:132:43:
  note: expanded from macro 'magick_hot_spot'
  # define magick_hot_spot __attribute__((__hot__))
  ^

Evidently magick/method-attribute.h (and wand/method-attribute.h) have an incomplete compiler version check. Here's what I see there:

• #if defined(__clang__) || (((__GNUC__) > 4) || ((__GNUC__ == 4) &&
  (__GNUC_MINOR__ >= 3)))
  # define magick_alloc_size(x) __attribute__((__alloc_size__(x)))
  # define magick_alloc_sizes(x,y) __attribute__((__alloc_size__(x,y)))
  # define magick_cold_spot __attribute__((__cold__))
  # define magick_hot_spot __attribute__((__hot__))
  #else
  ...
  #endif

The clang I'm using is

• $ clang++ --version
  Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
  Target: x86_64-apple-darwin11.4.2
  Thread model: posix

Unfortunately,

• #if defined(__has_attribute) && __has_attribute(__hot__)

is true on this compiler, and version number checking in clang is hard per http://sourceforge.net/p/predef/wiki/Compilers/
so a real fix might be hard.

If it's of interest, here's the commandline that failed:

• clang++ -I /Users/buildbot/slave-state/osx107/g-speak-rbb-osx107-1/sandbox-osx107-master3_13/build/gtest/include
  -mmacosx-version-min=10.7 -isystem /include -Wempty-body
  -fdiagnostics-show-option -Wall -Wpointer-arith -Wshadow
  -Wwrite-strings -Wno-overloaded-virtual -Wno-strict-overflow
  -Wno-error=unused-variable -Werror -g -O3 -std=gnu++0x
  -Wno-parentheses -Wno-unused-command-line-argument -Wno-shadow
  -DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -arch i386
  -arch x86_64 -isysroot
  /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk
  -I/Users/buildbot/slave-state/osx107/g-speak-rbb-osx107-1/sandbox-osx107-master3_13/build
  -I/opt/oblong/g-speak3.13/include -I/opt/oblong/deps-64-9/include
  -I/opt/oblong/deps-64-9/include/ImageMagick -o
  CMakeFiles/hydra.dir/examples/hydra/hydra.C.o -c
  /Users/buildbot/slave-state/osx107/g-speak-rbb-osx107-1/sandbox-osx107-master3_13/build/examples/hydra/hydra.C

[magick]

We'll add a patch to ImageMagick 6.8.8-8 Beta to fix the problem you reported. Thanks.

[DanKegel]

The patch helped, but a related problem remains. I will post on a new thread about the next problem.