The error is coming from godoc/spec.go, which is expected because that is where the EBNF parsing is done. But what is interesting is it doesn't happen if I compile godoc using go1.10, and only happens with the tip compiler. Which means something changed in the standard library which is causing this to fail.

And looking at the imports of that file, my money is on the "text/scanner" package.

Figured that it had to be the "text/scanner" package. Looked into the history of commits. Found culprit commit to be - c8915a0. The things a single-line change can do :)

Re-titling. Feel free to take appropriate action.

Thank you @agnivade for triaging.

\cc @SilverRainZ since he authored the change.

Thanks, @agnivade for tracking this down. I think the scanner change was correct; godoc/spec should probably accept raw strings where it only accepts strings.

Fix incoming. Will probably add a test while at it.

Change https://golang.org/cl/120659 mentions this issue: godoc: accept scanner.RawString too during EBNF parsing