This is a known bug for mac when trying to compile a Qt 5.0+ project with a 64-bit clang compiler. To resolve this conflict, try the steps described in this error on the forum:
1) Clone the Qt 5.0.0 clang desktop kit (SDK).
2) Change the compiler from GCC (x86 64 bit) to Clang (x86 64bit).
3) Change your project to use a cloned set.
4) Add the following file to your .pro file:
QMAKE_CXXFLAGS = -mmacosx-version-min=10.7 -std=gnu0x -stdlib=libc+ CONFIG +=c++11
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