[Version 12.0] Feature support for primary constructors

standard/arrays.md

@@ -36,7 +36,7 @@
 A *non_array_type* is any *type* that is not itself an *array_type*.
 
 When determining the rank and element type of array type as specified below, only the *rank_specifier*s in the outer-most production are considered, so in the production `array_type nullable_type_annotation rank_specifier+`, any `rank_specifier` within the `array_type` is ignored.
 
 The rank of an array type is given by the leftmost *rank_specifier* in the *array_type*: A *rank_specifier* indicates that the array is an array with a rank of one plus the number of “`,`” tokens in the *rank_specifier*.
 
 The element type of an array type is the type that results from deleting the leftmost *rank_specifier* from the *array_type*.
@@ -311,3 +311,8 @@
 
 <!-- markdownlint-enable MD028 -->
 > *Note*: C# allows a trailing comma at the end of an *array_initializer*. This syntax provides flexibility in adding or deleting members from such a list, and simplifies machine generation of such lists. *end note*
+
+A warning shall be produced for a *variable_initializer* when all the following conditions are true:
+
+- The variable initializer represents an implicit or explicit identity conversion of a primary constructor parameter (§prim-constructor);
+- The primary constructor parameter is captured into the state of the enclosing type.