Align more error messages with CPython 3.14.5 by ShaharNaveh · Pull Request #7933 · RustPython/RustPython

ShaharNaveh · 2026-05-20T08:47:57Z

Summary by CodeRabbit

Bug Fixes
- Improved syntax error messages with precise location details, including line numbers for unterminated string literals
- Added clearer error when arguments appear after var-keyword parameters
- Refined wording and formatting for several other syntax errors and made "expected …" messages more specific

github-actions · 2026-05-20T08:48:48Z

📦 Library Dependencies

The following Lib/ modules were modified. Here are their dependencies:

[ ] test: cpython/Lib/test/test_syntax.py (TODO: 253)

dependencies:

dependent tests: (no tests depend on syntax)

[x] test: cpython/Lib/test/test_eof.py (TODO: 5)

dependencies:

dependent tests: (no tests depend on eof)

Legend:

[+] path exists in CPython
[x] up-to-date, [ ] outdated

coderabbitai · 2026-05-20T08:50:21Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Run ID: 66d7efa8-706f-4ab1-beba-2d3668aef16d

📥 Commits

Reviewing files that changed from the base of the PR and between f3abe06 and c17af96.

⛔ Files ignored due to path filters (2)

Lib/test/test_eof.py is excluded by !Lib/**
Lib/test/test_syntax.py is excluded by !Lib/**

📒 Files selected for processing (1)

crates/vm/src/vm/vm_new.rs

📝 Walkthrough

Walkthrough

Error message handling in analyze_compile_error is enhanced to capture error location and improve parse error messages. The CompileError::Parse destructuring now binds location to enable precise error reporting. Subsequent error types receive updated messages: unterminated strings include detected line numbers, a new ParamAfterVarKeywordParam case is added, and multiple OtherError cases are rewritten with improved or raw-string formatting.

Changes

Parse Error Message Handling

Layer / File(s)	Summary
Parse error location binding `crates/vm/src/vm/vm_new.rs`	`CompileError::Parse` pattern destructuring is updated to bind `location` for use in downstream error-message formatting.
Error-type-specific message updates `crates/vm/src/vm/vm_new.rs`	Unterminated string errors now report detected line numbers, a new `ParamAfterVarKeywordParam` case is added with its message, and multiple `OtherError` string-match cases are rewritten with improved or raw-string formatting.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

RustPython/RustPython#7928: Modifies the same analyze_compile_error method and ParseErrorType cases in error-message mapping.

Suggested reviewers

youknowone

Poem

🐰 A compiler speaks clearer with location in sight,
Each parse error now tells where things went not right,
With line numbers glowing and messages refined,
The rabbit hops forward—no ambiguity in mind!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: aligning error messages with CPython 3.14.5, which matches the error message updates throughout the vm_new.rs file.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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youknowone

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@expectedfailure

Continues RustPython#7928/RustPython#7933/RustPython#7988. Translates many more ruff ParseErrorType variants to CPython's exact wording in CompileError::from_ruff_parse_error, and routes ast.parse() / compile(PyCF_ONLY_AST) through the same path so those messages match too (previously they leaked raw ruff strings). Adds a few codegen/symtable checks. Covered: aug-assign/delete/set/dict/f-string/t-string targets; "cannot use {kind} as import target"; string-prefix incompatibility and "invalid character 'X' (U+XXXX)"; parenthesized def/lambda params; missing default/argument value; dict ':' / value syntax; "'elif' block follows an 'else' block"; raise-from; comprehension 'if'; ternary statement keywords; match "case ... as <target>" -> "cannot use {kind} as pattern target" and "case ... as _"; __debug__ as def/class/type-param/except name; "name 'x' is nonlocal and global"; generic type-parameter wording. Lib/test: drop the now-passing "# TODO: RUSTPYTHON; Wrong error message" doctest markers and @expectedfailure decorators. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

@expectedfailure

Continues RustPython#7928/RustPython#7933/RustPython#7988. Translates many more ruff ParseErrorType variants to CPython's exact wording in CompileError::from_ruff_parse_error, and routes ast.parse() / compile(PyCF_ONLY_AST) through the same path so those messages match too (previously they leaked raw ruff strings). Adds a few codegen/symtable checks. Covered: aug-assign/delete/set/dict/f-string/t-string targets; "cannot use {kind} as import target"; string-prefix incompatibility and "invalid character 'X' (U+XXXX)"; parenthesized def/lambda params; missing default/argument value; dict ':' / value syntax; "'elif' block follows an 'else' block"; raise-from; comprehension 'if'; ternary statement keywords; match "case ... as <target>" -> "cannot use {kind} as pattern target" and "case ... as _"; __debug__ as def/class/type-param/except name; "name 'x' is nonlocal and global"; generic type-parameter wording. Lib/test: drop the now-passing "# TODO: RUSTPYTHON; Wrong error message" doctest markers and @expectedfailure decorators. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

@expectedfailure

Continues RustPython#7928/RustPython#7933/RustPython#7988. Translates many more ruff ParseErrorType variants to CPython's exact wording in CompileError::from_ruff_parse_error, and routes ast.parse() / compile(PyCF_ONLY_AST) through the same path so those messages match too (previously they leaked raw ruff strings). Adds a few codegen/symtable checks. Covered: aug-assign/delete/set/dict/f-string/t-string targets; "cannot use {kind} as import target"; string-prefix incompatibility and "invalid character 'X' (U+XXXX)"; parenthesized def/lambda params; missing default/argument value; dict ':' / value syntax; "'elif' block follows an 'else' block"; raise-from; comprehension 'if'; ternary statement keywords; match "case ... as <target>" -> "cannot use {kind} as pattern target" and "case ... as _"; __debug__ as def/class/type-param/except name; "name 'x' is nonlocal and global"; generic type-parameter wording. Lib/test: drop the now-passing "# TODO: RUSTPYTHON; Wrong error message" doctest markers and @expectedfailure decorators. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

@expectedfailure

Continues RustPython#7928/RustPython#7933/RustPython#7988. Translates many more ruff ParseErrorType variants to CPython's exact wording in CompileError::from_ruff_parse_error, and routes ast.parse() / compile(PyCF_ONLY_AST) through the same path so those messages match too (previously they leaked raw ruff strings). Adds a few codegen/symtable checks. Covered: aug-assign/delete/set/dict/f-string/t-string targets; "cannot use {kind} as import target"; string-prefix incompatibility and "invalid character 'X' (U+XXXX)"; parenthesized def/lambda params; missing default/argument value; dict ':' / value syntax; "'elif' block follows an 'else' block"; raise-from; comprehension 'if'; ternary statement keywords; match "case ... as <target>" -> "cannot use {kind} as pattern target" and "case ... as _"; __debug__ as def/class/type-param/except name; "name 'x' is nonlocal and global"; generic type-parameter wording. Lib/test: drop the now-passing "# TODO: RUSTPYTHON; Wrong error message" doctest markers and @expectedfailure decorators. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

@expectedfailure

Continues RustPython#7928/RustPython#7933/RustPython#7988. Translates many more ruff ParseErrorType variants to CPython's exact wording in CompileError::from_ruff_parse_error, and routes ast.parse() / compile(PyCF_ONLY_AST) through the same path so those messages match too (previously they leaked raw ruff strings). Adds a few codegen/symtable checks. Covered: aug-assign/delete/set/dict/f-string/t-string targets; "cannot use {kind} as import target"; string-prefix incompatibility and "invalid character 'X' (U+XXXX)"; parenthesized def/lambda params; missing default/argument value; dict ':' / value syntax; "'elif' block follows an 'else' block"; raise-from; comprehension 'if'; ternary statement keywords; match "case ... as <target>" -> "cannot use {kind} as pattern target" and "case ... as _"; __debug__ as def/class/type-param/except name; "name 'x' is nonlocal and global"; generic type-parameter wording. Lib/test: drop the now-passing "# TODO: RUSTPYTHON; Wrong error message" doctest markers and @expectedfailure decorators. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Align more error messages with CPython 3.14.5

f3abe06

ShaharNaveh added 2 commits May 20, 2026 12:14

Align patches for test_eof.py

575bcf2

Unmark passing test

6d46549

ShaharNaveh marked this pull request as draft May 20, 2026 09:44

Fix more

c17af96

ShaharNaveh marked this pull request as ready for review May 20, 2026 10:59

youknowone approved these changes May 20, 2026

View reviewed changes

youknowone merged commit ee006af into RustPython:main May 20, 2026
27 checks passed

coderabbitai Bot mentioned this pull request May 27, 2026

Align more error messages with CPython 3.14.5 #7988

Merged

JamesClarke7283 mentioned this pull request May 29, 2026

Align all remaining error messages with CPython #7993

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Align more error messages with CPython 3.14.5#7933

Align more error messages with CPython 3.14.5#7933
youknowone merged 4 commits into
RustPython:mainfrom
ShaharNaveh:ruff-error-msg-0

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📦 Library Dependencies

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