Document new method group conversion #28952
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Fixes dotnet#28942 Beginning in C# 11, the compiler is allowed to cache the delegate created from a method group conversion. The compiler now does this.
| The C# standard on [Method group conversions](~/_csharpstandard/standard/conversions.md#108-method-group-conversions) now includes the following item: | ||
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| > - The conversion is permitted (but not required) to use an existing delegate instance that already contains these references. | ||
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| Previous versions of the standard prohibited the compiler from reusing the delegate object created for a method group conversion. The C# 11 compiler caches the delegate object created from a method group conversion and reuses that single delegate object. This feature is first available in Visual Studio 17.2 as a preview feature. It is first available in .NET 7 preview 2. |
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That is a bit misleading. The quoted item was already in the C# 5 standard that ECMA published in 2017. If the C# compiler in .NET 7 SDK were changed to cache and reuse delegate instances whenever the language version is C# 5 or higher, then that would be allowed by the standards, although I understand if Microsoft won't do that because of the compatibility risk.
The following would be more correct:
The C# compiler now optimizes as permitted by the following item in the C# standard on Method group conversions:
- The conversion is permitted (but not required) to use an existing delegate instance that already contains these references.
Previous versions of the C# compiler did not reuse the delegate object created for a method group conversion, even though the C# 5 standard already allowed it. The C# 11 compiler caches the delegate object created from a method group conversion and reuses that single delegate object. This feature is first available in Visual Studio 17.2 as a preview feature. It is first available in .NET 7 preview 2.
Fixes #28942
Beginning in C# 11, the compiler is allowed to cache the delegate created from a method group conversion. The compiler now does this.