Rust API for pyinitconfig

[Person-93]

Adds a rust API to initialize the embedded interpreter with configuration.

Closes #6153

[ngoldbaum]

According to codecov almost none of the API surface is tested. Can you please make sure there's coverage for all the InitConfig methods you're proposing to add?

[bschoenmaeckers]

I think it is more appropriate to return the exit code as a variant of InitConfigError. And make this return Result<(), InitConfigError>

[Person-93]

I think it is more appropriate to return the exit code as a variant of InitConfigError. And make this return Result<(), InitConfigError>

I think you're right, I've double checked the docs, and it doesn't explicitly say that calling python APIs when the interpreter wants to exit is forbidden, but that is what the examples show.

[Person-93]

I think it should be a new error type with two variants, one of which wraps the existing error type. This way users who want to handle the exit code differently (i.e. by exiting with that code) don't need to check it at every call.

[bschoenmaeckers]

I think it should be a new error type with two variants, one of which wraps the existing error type. This way users who want to handle the exit code differently (i.e. by exiting with that code) don't need to check it at every call.

Agreed.

Should InitConfigError be just a CString/String? It feels like a unnecessary wrapper. What do you think?

[Person-93]

I think that libraries should define their own error types. https://doc.rust-lang.org/rust-by-example/error/multiple_error_types/define_error_type.html

[codspeed-hq]

Merging this PR will degrade performance by 25.83%

⚠️ 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

❌ 1 regressed benchmark
✅ 139 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	into_u128_u64_max	1.5 µs	2 µs	-25.83%

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 Person-93:pyinitconfig (f8416ab) with main (9e6697d)}

[Person-93]

@codspeedbot fix this regression

[Person-93]

Maintainers (@ngoldbaum), is test coverage OK. Do we need a test case which deliberately causes initialization to fail so the error handling code is covered?