From f4f82f0ab6431837f4aca19c20fd1d25913b70c5 Mon Sep 17 00:00:00 2001 From: chemelnucfin <3982092+chemelnucfin@users.noreply.github.com> Date: Fri, 1 May 2026 01:11:53 -0700 Subject: [PATCH] gh-133560: Clarified `parser.md` doc for pegen parser issue in using the existing `Grammar/python.gram` file. (GH-139194) Co-authored-by: Petr Viktorin --- InternalDocs/parser.md | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/InternalDocs/parser.md b/InternalDocs/parser.md index 1d0ffe6d40d..1bb4cdea543 100644 --- a/InternalDocs/parser.md +++ b/InternalDocs/parser.md @@ -819,6 +819,13 @@ directory on the CPython repository and manually call the parser generator by ex $ python -m pegen python ``` +> [!CAUTION] +> Python's grammar (the `Grammar/python.gram` file) is written for the +> C backend. To experiment, you will need to write a grammar +> without C-specific parts like actions and the trailer. +> See [#133560](https://github.com/python/cpython/issues/133560) +> and [#96424](https://github.com/python/cpython/issues/96424) for more information. + This will generate a file called `parse.py` in the same directory that you can use to parse some input: