Org reader: Fix Post standing for Pre in setEmphasisPreChar

[adql]

Small typing mistake which causes e.g. )/emph/) and (/noemph/) on the default pre-chars.

[adql]

I discovered this by chance while trying to work on #8059. It appeared in this commit about 4 years ago, go figure how this hasn't disturbed anyone so far (couldn't find a relevant issue).

[tarleb]

Thank you, good catch! If I understand correctly, then the bug was triggered only when the new "pre" setting could not be parsed.

[adql]

As I understand, it actually affected all parsing when no pandoc-emphasis-pre is set, i.e. the default behavior (since setEmphasisPreChar pulls the default from defaultOrgParserState when no setting is given, and until now it accidentally pulled the Post).

Kind of surprising that it went unnoticed, but then the only affected characters in the default setting are the directional ones ( and {. Maybe it's not very common to emphasize directly after an opening parenthesis.

[tarleb]

The function setEmphasisPreChar is called when the org-file contains a #+pandoc-emphasis-pre line. Pandoc treats the rest of that line as a Haskell expression that defines a string, i.e., it should be surrounded by double quotes. If that succeeds, then the pre chars are updated. If, however, the line does not contain a valid Haskell string, then setEmphasisPreChar is called with Nothing as the first argument. Only then does the fromMaybe evaluate the fallback value (its first argument).

The idea behind that mechanism is that a sole #+pandoc-emphasis-pre, without any arguments, will reset to the default behavior. That mechanism, as you found, was broken. The value was set to the allowed post chars instead of reset to its initial value.

[adql]

That's interesting. Where is the default behavior actually defined then?

I should mention that #+pandoc-emphasis-pre actually hardly works at all. I tested several cases and it seems like #8059 is broader than at first seemed. Most characters that I tried to add failed. The test in the suite only tests for [, which happens to pass.