I occasionally run into bugs in the compiler while writing (more of) the compiler (compiled by the compiler), and if they're not critical, sometimes I'll lazily throw them on the TODO list so I can keep working on the New Shiny instead of pausing to bugfix.
Discovered some cases where the stage1/stage2 compiler's error detection is less robust than the stage0 transpiler, resulting in me wasting time debugging some dumb typos while working on stage3 IR generation today...