Escape control characters in string constants as Python, not as Rust

[dylanpulver]

Display for PyStaticExpr renders string constants with {value:?}, which applies Rust's escaping rules. Rust writes an unprintable character as \u{1b}, and Python's \u escape takes exactly four hex digits, so that form is a SyntaxError rather than an escape.

Any string constant holding a C0 control character other than NUL, tab, newline or carriage return therefore renders as invalid Python. A signature default such as "\x1b[0m" is the realistic way to reach it.

The sibling renderer in pyo3-introspection/src/stubs.rs already writes \x1b here. This mirrors its escape table so the two agree. I noticed the split while reading both renderers after #6393.

The existing test covers "\0\t\\\"", the four characters whose Rust and Python escapes are identical, so the divergence did not show up.

[codspeed-hq]

Merging this PR will degrade performance by 15.72%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 5 regressed benchmarks
✅ 136 untouched benchmarks
⏩ 6 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	into_biguint_zero	1.1 µs	1.4 µs	-21.57%
❌	into_biguint_small	1.2 µs	1.5 µs	-21.54%
❌	into_bigint_small	2.6 µs	3 µs	-12.59%
❌	critical_section_creation	1.3 µs	1.5 µs	-11.24%
❌	extract_bigint_small	1.4 µs	1.5 µs	-10.94%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing dylanpulver:fix-str-constant-escapes (99852a5) with main (fe2eb7a)}

Footnotes

1. 6 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Tpt]

Thank you! That's a bit unfortunate to get this code duplicated but not sure setting up a way to get this code shared would be better