If a VarDecl has an explicit type expression, it will get evaluated once for each declared variable. So if you have a VarDecl like var x, y interface { M() } you end up with two different *types2.Interface objects.

I ran into this because I wanted to map all types2.Type objects (that appeared in source) back to some syntactic element, so my initial approach was to just walk the AST looking for type expressions and then using Info.Types[expr].Type to get the types2.Type object and insert them into a map[types2.Type]syntax.Expr map.

However, this approach missed some types, because of VarDecls with multiple variables and an explicit type expression.

I don't think this is strictly a violation of the types2 API (you're supposed to use types2.Identical), but I think it would be nice and less surprising if there was a 1:1 correspondance.

I assume this also affects go/types.

/cc @griesemer @findleyr