Segmentation fault when compiling with icpc

Hello,

I ran into a strange problem with icpc when compiling the attached C++ code. When I compile with icpc -O0 icpc_segfault.cpp -o icpc_segfault the program crashes with a segmentation fault. If I compile with any other optimization flag or with clang++ or g++, the program runs fine.

I can't see any UB in the code, so my only other guess is that it is a problem with icpc. The attached code is a stripped down version of the actual program. I can "fix" the segfault in the attached code in several ways (e.g., add a const data member to the FormatList class, or declare pointers volatile), but these "fixes" don't work in the actual program. This just makes me think even more so that it's a compiler problem and not UB.

The target architecture is intel64 and I tried several versions of icpc (16.0.4, 17.0.5, 18.0.3, 19.0.5.281).

Any help on this is appreciated. It can very well be that I just don't see the UB in the code.