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Stop definition list nesting short of the recursion limit - #1701
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waylan merged 3 commits intoNov 10, 2026
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DefListProcessor.run calls parseBlocks on the definition content, which can contain further definitions, so a document of flat term/definition pairs without blank lines nests once per pair and raises an uncaught RecursionError from only ~5 KB of input. DefListProcessor.test now declines to run near the recursion limit, the same guard BlockquoteProcessor already uses; the remaining markers are kept as text. Fixes Python-Markdown#1700 Co-authored-by: rahul05ranjan <11793455+rahul05ranjan@users.noreply.github.com>
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This looks good. Thank you. If you make the minor fix noted below and add a changelog entry, I'll merge this.
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Thanks for doing the work on this.
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Appreciate the merge on #1701 — nice to see "Stop definition list nesting short of the recursion limit" ship. On a personal note: I'm on the lookout for my next role (Full Stack (PHP, NodeJs, Python) / Data Science / Applied AI / Devtools, based in India). Happy to chat if there's an opening on your side or one you'd recommend: |
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Problem
The
def_listextension raises an uncaughtRecursionErroron a flat document of term/definition pairs without blank lines (#1700):DefListProcessor.runcallsparseBlockson the definition content, and with no blank lines each remainingterm\n: definitionpair nests one level deeper — so only ~5 KB of input (linear in recursion depth) reaches the interpreter's limit.Change
DefListProcessor.testnow declines to run near the recursion limit — the same guardBlockquoteProcessor.testalready applies — so the remaining markers are kept as text, exactly as for blockquotes and (per #1685) lists.Verification
TestDefListNestingLimit(tests/test_syntax/extensions/test_def_list.py), following the conventions of Stop list nesting short of the recursion limit #1685'sTestListNestingLimit: therecursionlimit(120)nesting-stops test and the 600-pair no-crash test fail on master (RecursionError), the shallow-nesting render test pins existing behavior; all pass with this changetests/test_syntax/extensions/test_md_in_html.pyexcluded locally (itsTestSuitehelper class doesn't collect under the host's pytest 9, an environment quirk unrelated to this change)PYTHONPATH(pygments2.21.0;markdownbuilt locally with the repo's ownsetup.pyfor entry-point loading); nothing installedFixes #1700