add more support for nullable references

Author: RexJaeschke

standard/statements.md

@@ -325,7 +325,14 @@ local_variable_initializer
 
 The *local_variable_type* of a *local_variable_declaration* either directly specifies the type of the variables introduced by the declaration, or indicates with the identifier `var` that the type should be inferred based on an initializer. The type is followed by a list of *local_variable_declarator*s, each of which introduces a new variable. A *local_variable_declarator* consists of an *identifier* that names the variable, optionally followed by an “`=`” token and a *local_variable_initializer* that gives the initial value of the variable.
 
-In the context of a local variable declaration, the identifier `var` acts as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)).When the *local_variable_type* is specified as `var` and no type named `var` is in scope, the declaration is an ***implicitly typed local variable declaration***, whose type is inferred from the type of the associated initializer expression. Implicitly typed local variable declarations are subject to the following restrictions:
+In the context of a local variable declaration, the identifier `var` acts as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)).When the *local_variable_type* is specified as `var` and no type named `var` is in scope, the declaration is an ***implicitly typed local variable declaration***, whose type is inferred from the type of the associated initializer expression.
+
+For reference types and type parameters that aren't constrained to be a value type, `var` infers an annotated type. For example:
+
+- in `var s = "";` var` is inferred as `string?`
+- in `var t = new T();` `var` is inferred as `T?`
+
+Implicitly typed local variable declarations are subject to the following restrictions:
 
 - The *local_variable_declaration* cannot include multiple *local_variable_declarator*s.
 - The *local_variable_declarator* shall include a *local_variable_initializer*.