SettingsBuilder: report warnings

This adds functionality to SettingsBuilder for collecting warnings to be
logged later, when the logging mechanism has been set up.

This also adds a validation step to update.php that aborts the update
if any warnings have been registered in SettingsBuilder, or the settings
fail to validate against the settings schema.

Change-Id: I387905289fb93591f79b96bf4c6cb5ec692b2aff

7 files changed, 86 insertions, 16 deletions

diff --git a/includes/MainConfigNames.php b/includes/MainConfigNames.php
index 5b477ec1ce6f..378f7526a40b 100644
--- a/includes/MainConfigNames.php
+++ b/includes/MainConfigNames.php
@@ -1794,7 +1794,6 @@ class MainConfigNames {
 	/**
 	 * Name constant for the DummyLanguageCodes setting, for use with Config::get()
 	 * @see MainConfigSchema::DummyLanguageCodes
-	 * @deprecated since 1.29
 	 */
 	public const DummyLanguageCodes = 'DummyLanguageCodes';
 
diff --git a/includes/MainConfigSchema.php b/includes/MainConfigSchema.php
index cd9a254c0477..b013265d9e59 100644
--- a/includes/MainConfigSchema.php
+++ b/includes/MainConfigSchema.php
@@ -4656,12 +4656,13 @@ class MainConfigSchema {
 	 * Functionally the same as $wgExtraLanguageCodes, but deprecated. Instead of
 	 * appending values to this array, append them to $wgExtraLanguageCodes.
 	 *
-	 * @deprecated since 1.29
+	 * @note Since 1.29, this should not be set directly in LocalSettings,
+	 *       ExtraLanguageCodes should be set instead. However, DummyLanguageCodes
+	 *       will be initialized and can be read internally.
 	 */
 	public const DummyLanguageCodes = [
 		'default' => [],
 		'type' => 'map',
-		'deprecated' => 'since 1.29',
 	];
 
 	/**
diff --git a/includes/Settings/SettingsBuilder.php b/includes/Settings/SettingsBuilder.php
index 3a31345eb1ed..47e807099276 100644
--- a/includes/Settings/SettingsBuilder.php
+++ b/includes/Settings/SettingsBuilder.php
@@ -80,6 +80,9 @@ class SettingsBuilder {
 	 */
 	private $defaultsNeedMerging = false;
 
+	/** @var string[] */
+	private $warnings = [];
+
 	/**
 	 * @param string $baseDir
 	 * @param ExtensionRegistry $extensionRegistry
@@ -196,6 +199,37 @@ class SettingsBuilder {
 	}
 
 	/**
+	 * Detect usage of deprecated settings. A setting is counted as used if
+	 * it has a value other than the default.
+	 *
+	 * @note this is slow, so you probably don't want to do this on every request.
+	 *
+	 * @return array<string,string> an associative array mapping config keys
+	 *         to the deprecation messages from the schema.
+	 */
+	public function detectDeprecatedConfig(): array {
+		$config = $this->getConfig();
+		$keys = $this->getDefinedConfigKeys();
+		$deprecated = [];
+
+		foreach ( $keys as $key ) {
+			$sch = $this->configSchema->getSchemaFor( $key );
+			if ( !isset( $sch['deprecated'] ) ) {
+				continue;
+			}
+
+			$default = $sch['default'] ?? null;
+			$value = $config->get( $key );
+
+			if ( $value !== $default ) {
+				$deprecated[$key] = $sch['deprecated'];
+			}
+		}
+
+		return $deprecated;
+	}
+
+	/**
 	 * Return a Config object with default for all settings from all schemas loaded so far.
 	 * If the schema for a setting doesn't specify a default, null is assumed.
 	 *
@@ -579,4 +613,30 @@ class SettingsBuilder {
 		return $this->configSink;
 	}
 
+	/**
+	 * Log a settings related warning, such as a deprecated config variable.
+	 *
+	 * This can be used during bootstrapping, when the regular logger is not yet available.
+	 * The warnings will be passed to a regular logger after bootstrapping is complete.
+	 * In addition, the updater will fail if it finds any warnings.
+	 * This allows us to warn about deprecated settings, and make sure they are
+	 * replaced before the update proceeds.
+	 *
+	 * @param string $msg
+	 */
+	public function warning( string $msg ) {
+		$this->assertNotFinished();
+		$this->warnings[] = trim( $msg );
+	}
+
+	/**
+	 * Returns any warnings logged by calling warning().
+	 *
+	 * @internal
+	 * @return string[]
+	 */
+	public function getWarnings(): array {
+		return $this->warnings;
+	}
+
 }
diff --git a/includes/Setup.php b/includes/Setup.php
index e0c36ba2f3ef..8ecb75a89910 100644
--- a/includes/Setup.php
+++ b/includes/Setup.php
@@ -566,6 +566,17 @@ if ( !$wgCommandLineMode ) {
 	Pingback::schedulePingback();
 }
 
+$settingsWarnings = $wgSettings->getWarnings();
+if ( $settingsWarnings ) {
+	$logger = LoggerFactory::getInstance( 'Settings' );
+	foreach ( $settingsWarnings as $msg ) {
+		$logger->warning( $msg );
+	}
+	unset( $logger );
+}
+
+unset( $settingsWarnings );
+
 // Explicit globals, so this works with bootstrap.php
 global $wgFullyInitialised;
 $wgFullyInitialised = true;
diff --git a/includes/SetupDynamicConfig.php b/includes/SetupDynamicConfig.php
index 5b803ba410ca..800874253a10 100644
--- a/includes/SetupDynamicConfig.php
+++ b/includes/SetupDynamicConfig.php
@@ -229,6 +229,10 @@ if ( !$wgLocaltimezone ) {
 	//       to gracefully handle the case of $wgLocaltimezone being the empty string.
 	//       See T305093#8063451.
 	$wgLocaltimezone = MainConfigSchema::getDefaultLocaltimezone();
+	$wgSettings->warning(
+		'The Localtimezone setting must a valid timezone string or null. '
+		. 'It must not be an empty string or false.'
+	);
 }
 
 // The part after the System| is ignored, but rest of MW fills it out as the local offset.
@@ -247,7 +251,10 @@ if ( is_array( $wgExtraNamespaces ) ) {
 
 // Hard-deprecate setting $wgDummyLanguageCodes in LocalSettings.php
 if ( count( $wgDummyLanguageCodes ) !== 0 ) {
-	wfDeprecated( '$wgDummyLanguageCodes', '1.29' );
+	$wgSettings->warning(
+		'Do not add to DummyLanguageCodes directly, ' .
+		'add to ExtraLanguageCodes instead.'
+	);
 }
 // Merge in the legacy language codes, incorporating overrides from the config
 $wgDummyLanguageCodes += [
@@ -273,10 +280,8 @@ if ( isset( $wgSlaveLagWarning ) ) {
 	// If the old value is set to something other than the default, use it.
 	if ( $wgDatabaseReplicaLagWarning === 10 && $wgSlaveLagWarning !== 10 ) {
 		$wgDatabaseReplicaLagWarning = $wgSlaveLagWarning;
-		wfDeprecated(
-			'$wgSlaveLagWarning set but $wgDatabaseReplicaLagWarning unchanged; using $wgSlaveLagWarning',
-			'1.36'
-		);
+		$wgSettings->warning( 'SlaveLagWarning is no longer supported, ' .
+			'use DatabaseReplicaLagWarning instead!' );
 	}
 } else {
 	// Backwards-compatibility for extensions that read this value.
@@ -287,10 +292,8 @@ if ( isset( $wgSlaveLagCritical ) ) {
 	// If the old value is set to something other than the default, use it.
 	if ( $wgDatabaseReplicaLagCritical === 30 && $wgSlaveLagCritical !== 30 ) {
 		$wgDatabaseReplicaLagCritical = $wgSlaveLagCritical;
-		wfDeprecated(
-			'$wgSlaveLagCritical set but $wgDatabaseReplicaLagCritical unchanged; using $wgSlaveLagCritical',
-			'1.36'
-		);
+		$wgSettings->warning( 'SlaveLagCritical is no longer supported, ' .
+			'use DatabaseReplicaLagCritical instead!' );
 	}
 } else {
 	// Backwards-compatibility for extensions that read this value.
diff --git a/includes/config-schema.php b/includes/config-schema.php
index ef4e72a30dbd..13eae4658687 100644
--- a/includes/config-schema.php
+++ b/includes/config-schema.php
@@ -3137,9 +3137,6 @@ return [
 		'SquidPurgeUseHostHeader' => [
 			'deprecated' => 'since 1.33',
 		],
-		'DummyLanguageCodes' => [
-			'deprecated' => 'since 1.29',
-		],
 		'RawHtmlMessages' => [
 			'items' => [
 				'type' => 'string',
diff --git a/includes/config-vars.php b/includes/config-vars.php
index 9b7200b2b8fb..34b101c27a2b 100644
--- a/includes/config-vars.php
+++ b/includes/config-vars.php
@@ -1778,7 +1778,6 @@ $wgExtraLanguageCodes = null;
 /**
  * Config variable stub for the DummyLanguageCodes setting, for use by phpdoc and IDEs.
  * @see MediaWiki\MainConfigSchema::DummyLanguageCodes
- * @deprecated since 1.29
  */
 $wgDummyLanguageCodes = null;