Inherent type for mapping constructor with no contextually expected type

[jclark]

When a mapping value is constructed by a mapping-constructor-expr that occurs in a context where there is no contextually expected type, what should the inherent type be? e.g.

var x = { a: 1 };

There are two contradictory principles that might be applied.

1. No contextually expected type is the same as a contextually expected type of any|error, which would imply inherent type would be map<any|error>, ie maximally permissive.
2. The type of members should be inferred in the same way as the type of variables, which would suggest the inherent type was record { int a; } or perhaps record {| int a; |}.

[jclark]

Note that the inherent type plays a much more fundamental role in the language than it did previously (when it was called storage type), since it now controls typing.

[jclark]

I think we need to distinguish the case where we are explicitly inferring the type from the expression (e.g. because var was used), from the case where we have a contextually expected type that allows anything.

[jclark]

A related point is whether the inferred type should be open or closed.

[jclark]

Conclusion after discussion was that the inferred type will allow each field have its own type and will be open to anydata.