That's definitely surprising, but it's worth noting that -debug-time-function-bodies is not a supported option.

Can you share the project? I don't think we're going to be able to reproduce this without your exact setup.

Comment by Alexey (JIRA)

For whatever reason I can't repro it anymore - everything works fine as expected and I see function timing in the output

I passes the flag as OTHER_SWIFT_FLAGS="-Xfrontend -debug-time-function-bodies" btw so it should be supported in this way.

That is how you do it, but that doesn't make it supported. Anything inside -Xfrontend is a compiler implementation detail, subject to change.

Comment by Alexey (JIRA)

Interesting! Is there any official way to pass this option to the swift compiler?

No, the option itself is not supported. As noted in the name, it's for debugging, and isn't necessarily an accurate picture of how long a function takes. It's not totally inaccurate either, though, especially for outlier expressions, so I get why people use it. cc @xedin

-Xfrontend -warn-long-function-bodies isn't supported either but at least has less of a chance of false conclusions, since people set moderately high thresholds.