@regehr @jrose @steve @porglezomp @bob ooh, i wasn't aware of this:
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-Og
quote:
> It [-Og] is a better choice than -O0 for producing debuggable code because some compiler passes that collect debug information are disabled at -O0.
but this is gcc's documentation, not clang's. Unfortunately, clang doesn't seem to document -O options at all, so i don't know whether this aspect of gcc's -O0/-Og is also true of clang's -O0/-Og.