It seems that when spaces are inserted in a format string like %#v, some slightly surprising formatting occurs.

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

Go 1.7.1 (on the Go playground)

What operating system and processor architecture are you using (go env)?

The Go playground.

What did you do?

https://play.golang.org/p/2jeholpKdb

What did you expect to see?

I would expect to see errors from fmt complaining about invalid format strings, or a literal representation of the string without the formatting applied, or the space simply be ignored. Instead, the formatting is applied in an inconsistent way.

What did you see instead?

main.Compound{C:(*main.Compound)(0x1040e130), A:5, B:"foo"}
main.Compound{C:(*main.Compound)( 0x1040e130), A: 5, B:"foo"}
main.Compound{C:(*main.Compound)( 0x1040e130), A: 5, B:"foo"}