compiler.rb in nanoc-4.0.0rc2

- old
+ new

@@ -38,10 +38,16 @@
   #
   # @api private
   class Compiler
     extend Nanoc::Int::Memoization
 
+    class IdenticalRoutesError < ::Nanoc::Error
+      def initialize(output_path, rep_a, rep_b)
+        super("The item representations #{rep_a.inspect} and #{rep_b.inspect} are both routed to #{output_path}.")
+      end
+    end
+
     # @group Accessors
 
     # @return [Nanoc::Int::Site] The site this compiler belongs to
     attr_reader :site
 
@@ -63,13 +69,13 @@
       @stack = []
     end
 
     # Compiles the site and writes out the compiled item representations.
     #
-    # Previous versions of nanoc (< 3.2) allowed passing items to compile, and
+    # Previous versions of Nanoc (< 3.2) allowed passing items to compile, and
     # had a “force” option to make the compiler recompile all pages, even
-    # when not outdated. These arguments and options are, as of nanoc 3.2, no
+    # when not outdated. These arguments and options are, as of Nanoc 3.2, no
     # longer used, and will simply be ignored when passed to {#run}.
     #
     # @overload run
     #   @return [void]
     def run(*_args)
@@ -213,10 +219,12 @@
 
     # Determines the paths of all item representations.
     #
     # @api private
     def route_reps
+      paths_to_reps = {}
+
       reps.each do |rep|
         # Find matching rules
         rules = rules_collection.routing_rules_for(rep)
         raise Nanoc::Int::Errors::NoMatchingRoutingRuleFound.new(rep) if rules[:last].nil?
 
@@ -224,9 +232,16 @@
           # Get basic path by applying matching rule
           basic_path = rule.apply_to(rep, executor: nil, compiler: self)
           next if basic_path.nil?
           if basic_path !~ %r{^/}
             raise "The path returned for the #{rep.inspect} item representation, “#{basic_path}”, does not start with a slash. Please ensure that all routing rules return a path that starts with a slash."
+          end
+
+          # Check for duplicate paths
+          if paths_to_reps.key?(basic_path)
+            raise IdenticalRoutesError.new(basic_path, paths_to_reps[basic_path], rep)
+          else
+            paths_to_reps[basic_path] = rep
           end
 
           # Get raw path by prepending output directory
           rep.raw_paths[snapshot] = @site.config[:output_dir] + basic_path
 