What version of Go are you using (go version)?

$ go version
go version go1.15 linux/amd64

It reproduces as far back as 1.12 (and probably further) and on tip.

What did you do?

If a function that should be displayed in tracebacks get inlined into a function that's elided from tracebacks, then neither of them appear. Here's a synthetic example: https://play.golang.org/p/fkGOZCT5h2W

As of CL 258938 (which is after 1.15), this happens in practice in cgo code. Exported Go functions (and functions they call) can now be inlined into the generated _cgoexp_HASH_FN function. The runtime elides _cgoexp_HASH_FN from tracebacks because it doesn't contain a ".". Because of this bug, that means it also elides anything that was inlined into it. (This is why I'm marking this as a release-blocker.)

What did you expect to see?

tracebackNotExcluded should appear in the traceback.

What did you see instead?

It does not.

This happens because gentraceback's inlined function trace printer passes the _func of the outermost function to showframe. It uses the name of that _func to make decisions about whether the frame should be shown, rather than the name of the inlined function about to be printed.