The elements in Grammar/python.gram stripped by peg_lexer.py still shows in generated PO files

My original question has answered by Stan. I leave it here as a record:

Click to expand

I'm not sure if it's done deliberately, but it seems odd to me and I can't find out why it happens so far.

The reference/grammar.rst includes Grammar/python.gram

Lines 18 to 19 in 78a50ee

    
           .. literalinclude:: ../../Grammar/python.gram 
        
             :language: peg

and Grammar/python.gram has a section for invalid rules at the bottom.

cpython/Grammar/python.gram

Lines 1193 to 1202 in 78a50ee

    
           # ========================= END OF THE GRAMMAR =========================== 
        
           # ========================= START OF INVALID RULES ======================= 
        
           # From here on, there are rules for invalid syntax with specialised error messages 
        
           invalid_arguments: 
        
               | ((','.(starred_expression | ( assignment_expression | expression !':=') !'=')+ ',' kwargs) | kwargs) a=',' ','.(starred_expression !'=')+ {

However, the content after START OF INVALID RULES is missing on the page

snapshot

I checked the previous version and found out the doc has this issue since 3.11 (after PEG parser is introduced).

Other info:
I translated this page into Traditional Chinese (zh-tw) recently and somehow it shows correctly on the translated page

snapshot

So here's the revised issue description:

Some elements in Grammar/python.gram are stripped by peg_lexer.py, and hence they're hidden on the reference/grammar docs. However, the full content of Grammar/python.gram is still remained in the generated PO files (e.g. the one in zh-tw).

Linked PRs

This is intentional, as the introduction states:

The version here omits details related to code generation and error recovery.

cpython/Doc/tools/extensions/lexers/peg_lexer.py

Lines 8 to 16 in e4d3c83

    
               This lexer strips the following elements from the grammar: 
        
                   - Meta-tags 
        
                   - Variable assignments 
        
                   - Actions 
        
                   - Lookaheads 
        
                   - Rule types 
        
                   - Rule options 
        
                   - Rules named `invalid_*` or `incorrect_*`

Why this is not done for translations is a bug.

ok thanks! I'll revise the issue description in-place then.

pythongh-142714: Strip hidden parts of the PEG grammar in all builders

Merge branch 'main' into pythongh-142714-peg-untranslatable

gh-142714: Exclude stripped PEG grammar text from translation catalogs (

[3.15] gh-142714: Exclude stripped PEG grammar text from translation …

[3.14] gh-142714: Exclude stripped PEG grammar text from translation …

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The elements in `Grammar/python.gram` stripped by `peg_lexer.py` still shows in generated PO files #142714

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	# ========================= END OF THE GRAMMAR ===========================



	# ========================= START OF INVALID RULES =======================

	# From here on, there are rules for invalid syntax with specialised error messages
	invalid_arguments:
	\| ((','.(starred_expression \| ( assignment_expression \| expression !':=') !'=')+ ',' kwargs) \| kwargs) a=',' ','.(starred_expression !'=')+ {

	This lexer strips the following elements from the grammar:

	- Meta-tags
	- Variable assignments
	- Actions
	- Lookaheads
	- Rule types
	- Rule options
	- Rules named `invalid_` or `incorrect_`

The elements in Grammar/python.gram stripped by peg_lexer.py still shows in generated PO files #142714

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StanFromIreland commented on Dec 14, 2025

mattwang44 commented on Dec 14, 2025

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The elements in `Grammar/python.gram` stripped by `peg_lexer.py` still shows in generated PO files #142714