fixing an invalid conversion in src/gpu/gl/GrGLCreateNullInterface.cpp

[luisbg]

Thanks :)

[kramerc]

Unfortunately, this change has caused building to fail when on Mac OS X.

Kramers-MacBook-Pro:build kramer$ make
mkdir -p `dirname src/gpu/gl/mac/GrGLCreateNativeInterface_mac.o` && c++ -c -fPIC -O3 -mssse3 -I/Users/kramer/Documents/Workspaces/servo/src/skia/include/config -I/Users/kramer/Documents/Workspaces/servo/src/skia/include/core -I/Users/kramer/Documents/Workspaces/servo/src/skia/include/effects -I/Users/kramer/Documents/Workspaces/servo/src/skia/include/gpu -I/Users/kramer/Documents/Workspaces/servo/src/skia/include/ports -I/Users/kramer/Documents/Workspaces/servo/src/skia/src/core -I/Users/kramer/Documents/Workspaces/servo/src/skia/src/image -iquote /Users/kramer/Documents/Workspaces/servo/src/skia/src/gpu  -I/Users/kramer/Documents/Workspaces/servo/src/skia/include/utils/mac  -o src/gpu/gl/mac/GrGLCreateNativeInterface_mac.o /Users/kramer/Documents/Workspaces/servo/src/skia/src/gpu/gl/mac/GrGLCreateNativeInterface_mac.cpp
/Users/kramer/Documents/Workspaces/servo/src/skia/src/gpu/gl/mac/GrGLCreateNativeInterface_mac.cpp:112:34: error: no viable overloaded '='
        interface->fShaderSource = glShaderSource;
        ~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~
/Users/kramer/Documents/Workspaces/servo/src/skia/include/gpu/gl/GrGLInterface.h:113:42: note: candidate function
      (the implicit copy assignment operator) not viable: no known conversion from 'void (GLuint, GLsizei, const GLchar **, const GLint *)' to 'const
      GrGLInterface::GLPtr<void (*)(unsigned int, int, const char *const *, const int *)>' for 1st argument
    template <typename FNPTR_TYPE> class GLPtr {
                                         ^
/Users/kramer/Documents/Workspaces/servo/src/skia/include/gpu/gl/GrGLInterface.h:116:15: note: candidate function not viable: no known conversion from
      'void (GLuint, GLsizei, const GLchar **, const GLint *)' to 'void (*)(unsigned int, int, const char *const *, const int *)' for 1st argument
        GLPtr operator =(FNPTR_TYPE ptr) { fPtr = ptr; return *this; }
              ^
1 error generated.
make[1]: *** [src/gpu/gl/mac/GrGLCreateNativeInterface_mac.o] Error 1
make: *** [/Users/kramer/Documents/Workspaces/servo/build/src/skia/lib*.dummy] Error 2

[jdm]

Paging @metajack.

[metajack]

What version of OS X and what version of Xcode do you have? It's building cleaning for me on 10.8.3 with XCode 4.6.1.

[kramerc]

I am on the same versions as you are. Changing const char* const* str back to const char** str did result in a successful build for me.

[metajack]

Did you upgrade your machine? The OpenGL headers I have from a fresh 10.8.3 install (and Xcode 4.6.1 was the first version installed here) require char* const* str, which is also the current specification of OpenGL. I'm just curious how we ended up with different headers.

In any case, the only fix for this will be to detect this issue and change the declaration accordingly. This happens in upstream Skia. I'll try and backport that today.

[kramerc]

My Mac originally came with 10.8.2. I noticed there was an update for Command Line Tools in the Xcode Preferences. After updating that, I now have the updated OpenGL headers that has const char* const* str and Skia builds successfully without my change.

[luisbg]

Kramer, what is your version of OpenGL after the upgrade?

[kramerc]

If I'm looking in the right spot, it appears to be OpenGL 1.8.7.25.0 according to Resources/Info.plist inside OpenGL.framework.

[jdm]

Should be fixed for all platforms as of 8f7ac7ba3742cde9c8a61d36e1251f9c766620ea.

[metajack]

Ok. I just pushed some changes that should fix this. I saw that upstream was using casts in this case sometimes, so I added the casts and everyone seems to report happiness.

[luisbg]

Tested this on Fedora 18. Works great Jack! Thanks :)