Compilation of the main document gives an error when using the bibtex package and the .bib file is located in a parent directory. More precisely, bibtex logs an error about output.aux: "I couldn't open database file [..]". The cause of this issue is that the output.aux file is placed under the root directory and bibtex is now trying to access the .bib file from a parent directory of the root.

See showcase-bibtex-issue as an example project demonstrating this issue.

Steps to Reproduce

1. Create a new blank project
2. Create a refs.bib file under the root directory.
3. Create or move a main.tex file under a subdirectory and refer to the .bib file as \bibliography{../refs.bib} (i.e., using bibtex).
4. Compile the main.tex file.

Expected Behaviour

The compilation should succeed without errors and produce a PDF with the used reference(s).

Observed Behaviour

The compiled PDF contains undefined citation(s) and logs the following error:

I couldn't open database file ../refs.bib : \bibdata{../refs.bib : }

Context

I want to compile documents with the same content (incl. bibliography) but with different styles. Therefore, I'm placing the content under the root and have multiple subdirectories containing each a single main file. In each main file, I refer to the content using \input{../[filename].tex} (this works as expected) and \bibliography{../[filename].bib} (this does not work as expected).

Technical Info

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Analysis

The issue comes from this line https://github.com/overleaf/overleaf/blob/main/services/clsi/app/js/LatexRunner.js#L158, where -auxdir= option for latexmk is defined as $COMPILE_DIR, which seems to point to the root directory, thus output.aux is placed there and not next to the main document (see the picture below, where output.aux should be in the "subdirectory" together with the main.tex).

As a solution, I suggest that output.aux is placed in the directory where latexmk is actually processing the main document so that bibtex understands the path correctly. This can be done, e.g., by modifying the option as -auxdir=./ (see the picture below, where output.aux is now in the "subdirectory" and the compilation succeeds).

PR of this fix is coming soon. PR of the fix available at #1068