In tikzcd I would like to draw an arrow with rounded corners which goes from an entry to an entry far right from it, and passes the row below them. It should not just be bent (this works with \ar[bend right=...]), it should rather look like half of a rectangle. Here is what almost works, except that one has to join the two arrows. Also, I would like to put the text "g' \circ g" on it. Probably one has to introduce a phantom node and tell the path to pass through it?
\begin{tikzcd}[column sep=34pt]
B \ar{r}[swap]{g}
\ar[to path= |- (\tikztotarget),rounded corners=12pt]{dr} & B'
\ar{r}[swap]{g'} & B'' \\
& \ar[to path= -| (\tikztotarget),rounded corners=12pt]{ru} &
\end{tikzcd}
Edit: In LaRiFari's solution, how can I put text on the arrow? My attempts do not work.
swapin the upper row arrows (or use\vphantom{'}in the first label). – egreg Feb 20 '16 at 11:35xshiftin order to give space for your big radii. If not, the arrow head will point in the wrong direction. – LaRiFaRi Feb 22 '16 at 08:54