Warn if date in file name of blogpost and in its content differ in scaladoc

scaladoc/src/dotty/tools/scaladoc/site/StaticSiteContext.scala

@@ -87,11 +87,22 @@ class StaticSiteContext(
 
         val templateFile = if (from.isDirectory) loadIndexPage() else loadTemplateFile(from)
 
-        val processedChildren = if !isBlog then children.sortBy(_.templateFile.title) else
-          def dateFrom(p: LoadedTemplate): String =
-            val pageSettings = p.templateFile.settings.get("page").collect{ case m: Map[String @unchecked, _] => m }
-            pageSettings.flatMap(_.get("date").collect{ case s: String => s}).getOrElse("1900-01-01") // blogs without date are last
-          children.sortBy(dateFrom).reverse
+        def dateFrom(p: LoadedTemplate, default: String = "1900-01-01"): String =
+          val pageSettings = p.templateFile.settings.get("page").collect{ case m: Map[String @unchecked, _] => m }
+          pageSettings.flatMap(_.get("date").collect{ case s: String => s}).getOrElse(default) // blogs without date are last
+
+        val processedChildren: Seq[LoadedTemplate] = if !isBlog then children.sortBy(_.templateFile.title) else
+          children.sortBy(dateFrom(_)).reverse
+
+        processedChildren.foreach { child =>
+          val regex = raw"(\d*-\d*-\d*)-(.*)".r
+          val setDate = dateFrom(child, "<no date>")
+          child.templateFile.name match
+            case regex(date, name) if date != setDate =>
+              val msg = s"Date $date in blog file: ${child.templateFile.name} doesn't match date from settings: $setDate."
+              report.warn(msg, from)
+            case name =>
+        }
 
         val processedTemplate = // Set provided name as arg in page for `docs`
           if from.getParentFile.toPath == docsPath && templateFile.isIndexPage() then