Make Message and MessageValue compatible

Fix two problems that made it difficult to convert between Message
and MessageValue, or to write code that could accept both of them,
as exemplified by the StatusValue class:

* Implement a common interface
* Use the same internal format for message parameters

While these changes should be compatible with most of existing code,
where the authors were courteous enough to simply call methods such
as Message::numParam() and not look inside the values they return,
it is potentially a breaking change for anything that depended on
the formatted params being arrays or accessed their keys.
Example patches: https://gerrit.wikimedia.org/r/q/topic:message-param

Notable changes:

* Message and MessageValue now both implement MessageSpecifier
  (only Message implemented it before).

* Message::numParam() and other static methods for encoding params
  now return MessageParam objects, instead of special arrays.
  Use these MessageParam objects internally in Message.

* Narrow down the return type of MessageSpecifier::getParams() (it
  was just `array`, allowing any type in the array). Narrow down the
  types for Message::params() and MessageValue::params() to match.

* Deprecate MediaWiki\Message\Converter. As a replacement add
  MessageValue::newFromSpecifier(), which is analogous to
  Message::newFromSpecifier(), but without weird legacy edge cases.

* Make StatusValue::getMessages() return MessageValues. Remove code
  that converted between Message and MessageValue, no longer needed.

* Update many type declarations and comments to use MessageSpecifier
  instead of MessageValue, as well as a couple of tests that depended
  on implementation details.

Bug: T358779
Change-Id: I625a48a6ecd3fad5c2ed76b23343a0fef91e1b83

1 files changed, 1 insertions, 1 deletions

diff --git a/includes/libs/Message/ListParam.php b/includes/libs/Message/ListParam.php
index 48823aa3808f..3b308915d828 100644
--- a/includes/libs/Message/ListParam.php
+++ b/includes/libs/Message/ListParam.php
@@ -20,7 +20,7 @@ class ListParam extends MessageParam {
 	 * @stable to call.
 	 *
 	 * @param string $listType One of the ListType constants.
-	 * @param (MessageParam|MessageValue|string|int|float)[] $elements Values in the list.
+	 * @param (MessageParam|MessageSpecifier|string|int|float)[] $elements Values in the list.
 	 *  Values that are not instances of MessageParam are wrapped using ParamType::TEXT.
 	 */
 	public function __construct( $listType, array $elements ) {