Make templates extensions with layouts configurable

CHANGELOG.md

@@ -20,6 +20,7 @@ master
 * Show an error message when git CLI is not available. #1765
 * Correctly show file names of GZIP'ed assets. #1364
 * Build file output is not parallel-ized! Use `middleman build --no-parallel` to disable.
+* Make template file extensions that get layouts by default configurable via `config[:extensions_with_layout]`
 
 # 4.0.0
 

middleman-core/lib/middleman-core/application.rb

@@ -149,9 +149,13 @@ module Middleman
     define_setting :http_prefix, '/', 'Default prefix for building paths'
 
     # Default layout name
-    # @return [String, Symbold]
+    # @return [String]
     define_setting :layout, :_auto_layout, 'Default layout name'
 
+    # Which file extensions have a layout by default.
+    # @return [Array.<String>]
+    define_setting :extensions_with_layout, %w(.html .xhtml .php), 'Which file extensions have a layout by default.'
+
     # Default string encoding for templates and output.
     # @return [String]
     define_setting :encoding, 'utf-8', 'Default string encoding for templates and output'

middleman-core/lib/middleman-core/sitemap/resource.rb

@@ -138,7 +138,7 @@ module Middleman
         locs[:current_path] ||= destination_path
 
         # Certain output file types don't use layouts
-        opts[:layout] = false if !opts.key?(:layout) && ext != '.html'
+        opts[:layout] = false if !opts.key?(:layout) && !@app.config.extensions_with_layout.include?(ext)
 
         renderer = ::Middleman::TemplateRenderer.new(@app, file_descriptor[:full_path].to_s)
         renderer.render(locs, opts)