Failure to compile with clang++ (undeclared identifier '_Unwind_GetIPInfo') about backward-cpp HOT 2 CLOSED

Changing to _Unwind_GetIP(ctx) makes it work, but I guess that can make for less accurate traces.

from backward-cpp.

Yep, exactly. Basically the tricks is that a trace address is where the code should come back after a call. So what you do, is decrementing one byte from the address so it somewhat falls into the boundaries of the previous instruction, which is usually the initial call that created the new stack frame.

In the case of a signal, the trace address is in fact the address of the bad instruction (for example a segfault), thus you dont want to decrement this one.

_Unwind_GetIPInfo gives you just that, this extra information.

I think if you declare _Unwind_GetIPInfo it will work. The function exists but is not declared in the unwind headers.

Note that it is possible to use libdw to do what unwind does, but unwind already does the job, and it is somewhat a little bit more portable (it abstracts away the format of the debug info).

from backward-cpp.