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After reading that the warning, Package biblatex Warning: Patching footnotes failed. is generated due to a redefinition of \@footnotetext by beamer I tried to retain its definition with the following patch. However, after compiling the document I noticed all my citations in the footnotes were gone. I use \footcitetext together with \footnotemark to have references in the footnotes. 

\makeatletter
\let\predefinedfootnotetext\@footnotetext
\makeatother

\documentclass[10pt, xcolor = {dvipsnames}, presentation]{beamer} % xcolor is already loaded with beamer 

\makeatletter
\let\@footnotetext\predefinedfootnotetext
\makeatother

Beamer patching footnotes warning: "Patching footnotes failed. Footnote detection will not work."

Such as the above most of the answers on this site suggest using the silence package, yet I wonder how to remedy this issue correctly. Some suggest editing the sty files, but it seems to be a daunting task.

What is the scope of this problem, when are you bound to run into trouble?

Vesnog
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    In most cases the warning is not a problem at all. Only if you use certain verbose-type styles or make a distinction between footnote and in-text citation and use other intricate features does it become relevant. In most other cases it can be safely ignored (or silenced). – moewe May 12 '17 at 08:46
  • @moewe I understood I want to correct it anyhow. How should I proceed then? – Vesnog May 12 '17 at 13:22
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    Why though? Do you need it? You will not benefit from a change if you don't use any of the affected features (which is unlikely). You would have to hack the redefinition of footnote in beamer and even then you are probably not done. You would have to have the biblatex developers include this in the biblatex code. – moewe May 12 '17 at 13:31
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    @Vesnog If the warning does not cause you any problems, I would not mess with beamer footnotes - they are quite clever, overlay aware and everything, and the only thing you gain is the risk to break nice beamer features... – samcarter_is_at_topanswers.xyz May 12 '17 at 13:49
  • @samcarter It should be possible to patch beamer's footnote though. I could almost get it running, but then patching fails because of an incorrect category code regime in beamer. – moewe May 12 '17 at 14:01
  • @samcarter I thought it would be educational for me and I will have a better understanding of Latex after finding out the reason why my style did not work and why this error happens. – Vesnog May 12 '17 at 19:52
  • One challenge I found when fixing a similar issue with bidi is that you also need to deal with how hyperref interacts with footnotes. And you would probably need to take care of interactions with bidi too to did things properly. – David Purton May 12 '17 at 22:33
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    My attempts to look at this did not work out, but we have a ticket at the biblatex bug tracker for this (https://github.com/plk/biblatex/issues/581). So if there is a solution here that can be implemented in biblatex, that would be great. – moewe Oct 29 '17 at 15:19

1 Answers1

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Starting from version 3.10, biblatex is able to detect footnotes automatically with beamer, the warning will be gone.

biblatex needs to patch the \@footnotetext commands to include \toggletrue{blx@footnote} to be able to detect if it is in a footnote or not. The usual approach is just a \patchcmd to the respective macro. But beamer needs to do some clever stuff with its version of \@footnotetext called \beamer@framefootnotetext so that patching has to look a bit different.

The necessary code can be found in https://github.com/plk/biblatex/commit/5169d2a64777090aa29d38df7543301f5c8b876b

The gist is that we had to use

\expandafter\patchcmd\csname beamerx@\string\beamer@framefootnotetext\endcsname
  {\color@begingroup}
  {\color@begingroup\toggletrue{blx@footnote}}
  {\togglefalse{blx@tempa}}
  {}

instead of just \patchmd{\beamer@framefootnotetext}.

moewe
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