incorrect citation output with biblatex and bibtex8 backend

[KonradHoeffner]

When I compile the following document with pdflatex v3.141592653-2.6-1.40.26 and bibtex or latexmk -pdf v4.83 using texlive 2024.2-3, the citation gets correctly written as Lastname and Anotherlastname 2024.
However when I use tectonic v0.15.0-2 instead (default pacman Arch Linux package "tectonic"), I get the incorrect output “Article Title” 2024.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[backend=bibtex8,bibencoding=ascii,style=authoryear]{biblatex}
\begin{filecontents}{mwe.bib}
@article{mwe,  
  title={Article Title},
  author={Firstname Lastname and Anotherfirstname Anotherlastname},
  journal={Journalname},
  volume={123},
  number={1},
  pages={1234--2345},
  year={2024}
}
\end{filecontents}
\addbibresource{mwe.bib}
\begin{document}
\cite{mwe}
\printbibliography
\end{document}

[xymaxim]

Same issue for me for the same setup.

As for a title being printed instead of authors, that's a known behavior (see sec. 2.3.2):

The author-year citation styles which come with this package use the label field as a fallback if either the author/editor or the year is missing.

For some reason, the labelname list is not populated in our case, and so the cite:label bibmacro is called:

https://github.com/plk/biblatex/blob/v3.17/tex/latex/biblatex/cbx/authoryear.cbx#L10-L18

Comparing the main.bbl file (attached) with the one produced with texlive, I noticed that the following line is missing in the first file: \field{labelnamesource}{author}. Printing the author field with biblatex's \printnames{author} or \usebibmacro{author} works just fine. So, a new command declared with \DeclareCiteCommand could be a temporary workaround.

issue-1231-files.zip

[KonradHoeffner]

@xymaxim: Thank you for confirming the bug and for the investigation. Can you elaborate on how that workaround with \DeclareCiteCommand would look like?

[xymaxim]

@KonradHoeffner Here is below an example of the new \mycite citation command for a parenthetical, APA-like in-text citations.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[backend=bibtex8,hyperref=true,maxcitenames=2]{biblatex}
\usepackage{hyperref}
\usepackage{citeall}

\addbibresource{\jobname.bib}

\renewcommand*{\nameyeardelim}{\addcomma\space}
\renewcommand*{\finalnamedelim}{\addspace\&\space}

\DeclareNameFormat{only-family}{%
  \usebibmacro{name:family}{\namepartfamily}{}{}{}
  \usebibmacro{name:andothers}}

\newbibmacro*{authororeditor}{%
  {\ifnameundef{author}
    {\printnames[only-family]{editor}}
    {\printnames[only-family]{author}}}}

\DeclareCiteCommand{\mycite}[\mkbibparens]
  {\usebibmacro{prenote}}%
  {\printtext[bibhyperref]{%
      \usebibmacro{authororeditor}%
      \setunit{\nameyeardelim}%
      \printfield{year}}}
  {\multicitedelim}%
  {\usebibmacro{postnote}}
  
\begin{document}
\citeall[\mycite]
\printbibliography
\end{document}

Given the sample BibTeX items:

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{one-author,
  title   = {Article Title},
  author  = {First, A.},
  journal = {Journal Title},
  year    = {2024},
}
@article{two-authors,
  title   = {Article Title},
  author  = {First, A. and Second, B.},
  journal = {Journal Title},
  year    = {2024},
}
@article{three-authors,
  title   = {Article Title},
  author  = {First, A. and Second, B and Third, C.},
  journal = {Journal Title},
  year    = {2024},
}
@book{only-editor,
  title     = {Book Title},
  editor    = {Editor, A.},
  publisher = {Publisher},
  year      = 2024
}
\end{filecontents}

It outputs:

(First, 2024)
(First & Second, 2024)
(First et al., 2024)
(Editor, 2024)

Not the cleanest solution and doesn't cover all cases, but I hope it may give you an idea to adapt as per your need.