Add ToString and PrintMembers to records

[jcouv]

@dotnet/roslyn-compiler for review. This is a proposal for shape of ToString synthesized members.

[333fred]

Extra newline.

[CyrusNajmabadi]

this feels unneeded. why not just always include a trailing comma. then you have the consistent, copyable:

Person
{
  Name = "Julien",
  Age = 99,
}

[CyrusNajmabadi]

https://sharplab.io/#v2:EYLgtghgzgLgpgJwDQxAgrgOwD4AEBMAjALABQuAzAAQFUDCVA3mVazfvky2zwG4QIqADyoBeKpjgB3JlQCCYqgCJJMgEKyG4wlQC+SvQG5uPVrkIA6OgHtMUawBs4FgOoIAlvAAUQiwBVrAGUYD0wAcy8ASkjjUh5dMl0gA

THat's extremely ick. Should we be taking a page from Go's book here: %#v

[333fred]

Suggested change

The method can be declared explicitly. It is an error if the explicit declaration does not match the expected signature or accessibility, or if the explicit declaration doesn't allow overiding it in a derived type and the record type is not `sealed`. It is an error if either synthesized, or explicitly declared method doesn't override `object.ToString()` (for example, due to shadowing in intermediate base types, etc.).

The method can be declared explicitly. It is an error if the explicit declaration does not match the expected signature or accessibility, or if the explicit declaration doesn't allow overiding it in a derived type and the record type is not `sealed`. It is an error if either synthesized or explicitly declared method doesn't override `object.ToString()` (for example, due to shadowing in intermediate base types, etc.).

[jcouv]

FYI, I'm going to revert to a speakable print method. Unspeakable print methods would throw a big wrench in our ability to derive records from classes. That seems unnecessary. I'll update the spec this afternoon.

Tagging @dotnet/roslyn-compiler

[333fred]

FYI, I'm going to revert to a speakable print method. Unspeakable print methods would throw a big wrench in our ability to derive records from classes. That seems unnecessary. I'll update the spec this afternoon.

That's a very good point, thanks Julien.

[jcouv]

I'll merge this spec change shortly. The unresolved follow-up questions were added to the records test plan. Thanks for the review

• ToString: should we always print a trailing comma R { Property1 = 42, Property2 = 43, }?
• ToString: can we deal with stack overflow potential?
• ToString: should we try to quote/escape values, for example R { IntProperty = 42, StringProperty = "hello" }?
• ToString: should we omit ToString on abstract records?