Fsharp: Improve error reporting: Missing = on type declaration

[isaacabraham]

What

The following error message is generated from this code sample

type Person { Name : string; Age : int; City : string }

error FS0010: Unexpected symbol '{' in type definition. Expected '(' or other token.

Why

The error message suggests to the user that they should put a ( in to fix the problem (or some other unspecified token), when in fact they have missed the = operator. Many other languages allow you to define types without the = sign, so this is not an uncommon issue.

How

Rewrite the above error to something like error FS0010: Unexpected symbol '{' in type definition. Did you forget to use the = operator e.g. "type Person = { Name ..." .

[smoothdeveloper]

I happen to frequently miss the equal when I defined classes, which breaks intellisense.

I do not do it as much with records or DUs but I think it would be helpful to identify the likely case to have better error messages.

[smoothdeveloper]

Related #1826

[cartermp]

Implemented in https://github.com/dotnet/fsharp/pull/9642

[isaacabraham]

Whoo!