List refactoring (v6)

UPGRADING.md

@@ -1,6 +1,12 @@
 # Upgrading from Psalm 4 to Psalm 5
 ## Changed
 
+- [BC] Psalm 5.1 will switch its internal representation of `list<T>` and `non-empty-list<T>` from the TList and TNonEmptyList classes to an unsealed list shape: the TList, TNonEmptyList and TCallableList classes will be removed.
+  Nothing will change for users: `list<T>` and `non-empty-list<T>` syntax will remain supported and its semantics unchanged.
+  Psalm 5.0 already deprecates the `TList`, `TNonEmptyList` and `TCallableList` classes: use `\Psalm\Type::getListAtomic`, `\Psalm\Type::getNonEmptyListAtomic` and `\Psalm\Type::getCallableListAtomic` to instantiate list atomics, or directly instantiate TKeyedArray objects with `is_list=true` where appropriate.
+
+- [BC] The only optional boolean parameter of `TKeyedArray::getGenericArrayType` was removed, and will be replaced with a string parameter with a different meaning in Psalm 5.1.
+
 - [BC] Shaped arrays can now be sealed: this brings many assertion improvements and bugfixes, see [the docs for more info](https://psalm.dev/docs/annotating_code/type_syntax/array_types/#sealed-object-like-arrays).
 
 - [BC] All atomic types, `Psalm\Type\Union`, `Psalm\CodeLocation` and storages are fully immutable, use the new setter methods or the new constructors to change properties: these setter methods will return new instances without altering the original instance.  

docs/running_psalm/plugins/plugins_type_system.md

@@ -185,8 +185,6 @@ foreach (range(1,1) as $_) $a[(string)rand(0,1)] = rand(0,1); // array<string,in
 
 `TCallableArray` - denotes an array that is _also_ `callable`.
 
-`TCallableList` - denotes a list that is _also_ `callable`.
-
 `TCallableKeyedArray` - denotes an object-like array that is _also_ `callable`.
 
 `TClassStringMap` - Represents an array where the type of each value is a function of its string key value