Raise error if `--citeproc` used with `--natbib` or `--biblatex`

[wenkokke]

Related to #9640.

Explain the problem. Assume the following documents:

• sample.md:

  We all love the famous proof by @BenjaminHornigold [p. 42].
  But is it real?
  No. Probably not.

• sample.bib:

  @book{BenjaminHornigold,
  author = {Benjamin Hornigold},
  title  = {A proof of Pirate ipsum},
  year   = {1680},
  }

To illustrate the issue, let us run Pandoc with three different configurations:

1. harvard.yaml

   input-files: [sample.md]
   output-file: harvard.pdf
   citeproc: true
   csl: harvard.csl
   bibliography: sample.bib

   yields

   

2. natbib.yaml

   input-files: [sample.md]
   output-file: natbib.pdf
   standalone: true
   citeproc: true
   cite-method: natbib
   resource-path: ["."]
   metadata:
     bibliography: sample.bib
   pdf-engine: "latexmk"

   yields

   

3. natbib-harvard.yaml

   input-files: [sample.md]
   output-file: natbib-harvard.pdf
   standalone: true
   citeproc: true
   csl: harvard.csl
   cite-method: natbib
   resource-path: ["."]
   metadata:
     bibliography: sample.bib
   pdf-engine: "latexmk"

   also yields

   

In (1), Pandoc typesets the page reference according to Harvard citation style. In (2), Pandoc typesets the page reference according to Chicago citation style, which is the default style. In (3), Pandoc typesets the page reference according to Chicago citation style, even though Harvard citation style is specified.

The expected behaviour would be for Pandoc to typeset the references according to the given citation style. I understand that technically I am giving Pandoc conflicting instructions. Render citations according to Harvard style and delegate to the natbib package. However, there is no option not to typeset the citation notes according to the default Chicago style, even though I am asking Pandoc to delegate to natbib. Therefore, I would argue that Pandoc's behaviour is definitely incorrect in (3), but that it is unclear whether Pandoc should (a) pass any notes through to natbib unchanged, or (b) attempt to typeset the notes using whatever citation style is provided.

Pandoc version? Running Pandoc 3.2.1 on macOS 13.

pandoc 3.2.1
Features: +server +lua
Scripting engine: Lua 5.4
User data directory: /Users/keri/.local/share/pandoc
Copyright (C) 2006-2024 John MacFarlane. Web: https://pandoc.org
This is free software; see the source for copying conditions. There is no
warranty, not even for merchantability or fitness for a particular purpose.

[jgm]

Please read the manual entry for --natbib: it is not to be used together with --citeproc.

[wenkokke]

Shouldn't that raise a warning or error?

[jgm]

Yes, it would make sense for us to raise an error if --natbib or --biblatex is used with --citeproc.