In the early days of C++11, I used to get unique ICEs in both GCC and Clang weekly. One particular annoyance was when a stable release of Debian decided to ship

In the early days of C++11, I used to get unique ICEs in both GCC and Clang weekly. One particular annoyance was when a stable release of Debian decided to ship a point release with a regression (not looking it up, but it was something like: 4.6.1 or 4.6.3 worked, but 4.6.2 had completely broken UDLs for constant expressions or something). I had just converted the whole codebase to use UDLs aggressively since they worked everywhere in my tests, not thinking I had to test every point release in between ... Thankfully I don't think I ever had any miscompilations - that would require the code actually compile across several compiler versions in the first place.