[UBSan] call to function through pointer to incorrect function type when running C++ API examples

[delcypher]

When building Z3 with UBSan, when the C++ api examples are executed the following error is reported.

/home/user/z3_src/src/api/api_context.cpp:278:13: runtime error: call to function (unknown) through pointer to incorrect function type 'void (*)(_Z3_context *, Z3_error_code)'
(/home/user/z3_build/examples/cpp_example_build_dir/cpp_example+0x4ad480): note: (unknown) defined here

This is for 110d558

[delcypher]

Unfortunately the UBSan error is still there, although now the error message has changed.

/home/user/z3_src/src/api/api_context.cpp:278:13: runtime error: call to function z3::context::error_handler(_Z3_context*, Z3_error_code) through pointer to incorrect function type 'void (*)
(_Z3_context *, Z3_error_code)'
/home/user/z3_src/src/api/c++/z3++.h:143: note: z3::context::error_handler(_Z3_context*, Z3_error_code) defined here
SUMMARY: AddressSanitizer: undefined-behavior /home/user/z3_src/src/api/api_context.cpp:278:13 in 

I will continue to suppress this warning in TravisCI. The code looks okay to me so I suggest we just keep this issue open until we figure out if this actually a bug or a problem with UBSan.

[NikolajBjorner]

suppressing issue