[cfe-dev] How to break in debugger when -fsanitize=undefined prints something?

[Alexander Shaduri]

Hello,

I'm trying out the -fsanitize=undefined option with clang
(Linux, x86-64) and I'm getting a few runtime warnings
with the code I'm working with.

I'd like to set a breakpoint on a function that prints these
warnings so that I can actually see the backtrace, but
I can't figure out how to do that.

I know there's -fsanitize-undefined-trap-on-error, but it
causes "Illegal Instruction" on the first warning, and due
to this warning being in another library, I cannot fix it and
continue to my own code.

Here's one of the warnings I get, but cannot debug because
I cannot find the actual location:
liblocal_qwt.so:0x4732fe: runtime error: load of value 4294967199, which is not a valid value for type 'Qt::AlignmentFlag'

Thanks in advance,
Alexander