documentation: percent character needs escaping in nested \href

[bastistician]

hyperref/doc/hyperref-doc.tex

Lines 1276 to 1277 in d656e81

	special characters \# and \~{} do \emph{not} need to be escaped in any
	way (unless the command is used in the argument of another command).

It seems that the tilde does not need to be escaped in \href URLs, even if used as an argument of another command.
For example, the following minimal LaTeX document compiles fine:

\documentclass{article}
\usepackage{hyperref}
\begin{document}
\emph{\href{https://example.org/~a}{tilde}}
\end{document}

However, the hash and percent symbols do need to be escaped in that case.
For example, the following fails, but would work with backslash-escaped percent or without the \emph:

\documentclass{article}
\usepackage{hyperref}
\begin{document}
\emph{\href{https://example.org/a%20b}{space}}
\end{document}

Runaway argument?
{\href {https://example.org/a\end {document} 
! File ended while scanning use of \emph .

Could this be a typo in the documentation referenced at the top?

[muzimuzhi]

I see no typos in doc. The referenced doc talks about hash and tilde only, but your second example demonstrates percent char which do need to be escaped.

[bastistician]

Thanks for confirming. With "typo" I meant that the \~{} could be replaced by \% in that sentence.

Note that both # and % need no escaping in "normal" use, but they do if \href is used as an argument to another command. In contrast, the tilde seems to work without escaping (but maybe other examples are needed, I'm not sure).

[u-fischer]

yes I think \% is meant in this context and I changed the text. The next update will have it.

[muzimuzhi]

With "typo" I meant that the \~{} could be replaced by \% in that sentence.

@bastistician You're right. I overlooked the "(unless ...)" part, sorry.