Disallow method parameter conversion of ref to in/ref readonly
#7820
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| @@ -255,6 +274,25 @@ The same warning could be reported when using custom collection initializer or i | |||
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| #### [Method conversions][method-conversions] | |||
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| We could allow conversions of `ref` to `in`/`ref readonly`. | |||
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Can we make this a bit more clear? Like saying
We could allow conversions of
refparameters in lambda expressions toin / ref readonlyparameters
| Similarly, for the purpose of anonymous function [[§10.7](https://github.com/dotnet/csharpstandard/blob/47912d4fdae2bb8c3750e6485bdc6509560ec6bf/standard/conversions.md#107-anonymous-function-conversions)] and method group [[§10.8](https://github.com/dotnet/csharpstandard/blob/47912d4fdae2bb8c3750e6485bdc6509560ec6bf/standard/conversions.md#108-method-group-conversions)] conversions, these modifiers are considered compatible | ||
| (but any allowed conversion between different modifiers results in a warning): | ||
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| - `ref readonly` can be interchanged with `in` and converted to `ref` modifier (but `ref` cannot be converted to `ref readonly`), |
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I find this wording confusing. We are not converting modifiers. Interchangeability is also a confusing term in this context, I think. Are we trying to say that a ref readonly parameter of the target method is allowed to match in or ref parameter of the delegate, but ref parameter of the target method is not allowed to match in or ref readonly parameter of the delegate? Consider using this wording then.
| (but any allowed conversion between different modifiers results in a warning): | ||
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| - `ref readonly` can be interchanged with `in` and converted to `ref` modifier (but `ref` cannot be converted to `ref readonly`), | ||
| - `in` can be converted to `ref` modifier, gated on LangVersion (but `ref` cannot be converted to `in`). |
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Consider rewording as suggested for the previous bullet point. It actually feels like it would be better to have three bullet points.
- for
ref readonlyparameter of the target method - for
inparameter of the target method - for
refparameter of the target method
| @@ -255,6 +274,25 @@ The same warning could be reported when using custom collection initializer or i | |||
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| #### [Method conversions][method-conversions] | |||
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| We could allow conversions of `ref` method/lambda parameters to `in`/`ref readonly` delegate parameters. | |||
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Similar comment for this statement. I have no idea what converting parameters mean, I do not think language has a concept like that.
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Done with review pass (commit 2) |
Related to dotnet/roslyn#71383.
Corresponding roslyn implementation: dotnet/roslyn#71531
Test plan: dotnet/roslyn#68056