From 835833ea8a7e479d1c43a92f7dfb52381ab6557e Mon Sep 17 00:00:00 2001
From: Timo Tijhof <krinklemail@gmail.com>
Date: Tue, 14 Feb 2017 16:25:39 -0800
Subject: [PATCH] OutputPage: Log violations of module 'target' filter

Bug: T140675
Change-Id: Icf9a2e72b663e363e8c87d5d464892c2bbbe78b2
---
 includes/OutputPage.php | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/includes/OutputPage.php b/includes/OutputPage.php
index af8243646b..eb2f7e7069 100644
--- a/includes/OutputPage.php
+++ b/includes/OutputPage.php
@@ -534,14 +534,32 @@ class OutputPage extends ContextSource {
 			if ( $module instanceof ResourceLoaderModule
 				&& $module->getOrigin() <= $this->getAllowedModules( $type )
 				&& ( is_null( $position ) || $module->getPosition() == $position )
-				&& ( !$this->mTarget || in_array( $this->mTarget, $module->getTargets() ) )
 			) {
+				if ( $this->mTarget && !in_array( $this->mTarget, $module->getTargets() ) ) {
+					$this->warnModuleTargetFilter( $module->getName() );
+					continue;
+				}
 				$filteredModules[] = $val;
 			}
 		}
 		return $filteredModules;
 	}
 
+	private function warnModuleTargetFilter( $moduleName ) {
+		static $warnings = [];
+		if ( isset( $warnings[$this->mTarget][$moduleName] ) ) {
+			return;
+		}
+		$warnings[$this->mTarget][$moduleName] = true;
+		$this->getResourceLoader()->getLogger()->debug(
+			'Module "{module}" not loadable on target "{target}".',
+			[
+				'module' => $moduleName,
+				'target' => $this->mTarget,
+			]
+		);
+	}
+
 	/**
 	 * Get the list of modules to include on this page
 	 *
-- 
2.20.1