Fix modular header access to header_dirs

CHANGELOG.md

@@ -13,6 +13,10 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
 
 ##### Bug Fixes
 
+* Fix modular header access to header_dir's.  
+  [Paul Beusterien](https://github.com/paulb777)
+  [#7597](https://github.com/CocoaPods/CocoaPods/issues/7597)
+
 * Inhibit warnings for all dependencies during validation except for the one being validated  
   [Dimitris Koutsogiorgas](https://github.com/dnkoutso)
   [#7434](https://github.com/CocoaPods/CocoaPods/issues/7434)

lib/cocoapods/target/pod_target.rb

@@ -600,7 +600,11 @@ module Pod
       dependent_targets = recursive_dependent_targets
       dependent_targets += recursive_test_dependent_targets if include_test_dependent_targets
       dependent_targets.each do |dependent_target|
-        header_search_paths.concat(sandbox.public_headers.search_paths(platform, dependent_target.pod_name, defines_module? && dependent_target.uses_modular_headers?(false)))
+        header_search_paths.concat(sandbox.public_headers.search_paths(platform,
+                                                                       dependent_target.pod_name,
+                                                                       defines_module? &&
+                                                                         dependent_target.uses_modular_headers?(false) &&
+                                                                         dependent_target.spec_consumers.none?(&:header_dir)))
       end
       header_search_paths.uniq
     end

spec/unit/target/pod_target_spec.rb

@@ -326,6 +326,23 @@ module Pod
           ]
         end
 
+        it 'returns the correct header search paths for dependent targets with header_dir set' do
+          @pod_target.build_headers.add_search_path('BananaLib', Platform.ios)
+          @pod_target.sandbox.public_headers.add_search_path('BananaLib', Platform.ios)
+          @pod_target.sandbox.public_headers.add_search_path('monkey', Platform.ios)
+          @monkey_pod_target = fixture_pod_target('monkey/monkey.podspec')
+          @monkey_pod_target.stubs(:platform).returns(Platform.ios)
+          @pod_target.stubs(:dependent_targets).returns([@monkey_pod_target])
+          @file_accessor = @monkey_pod_target.file_accessors.first
+          @file_accessor.spec_consumer.stubs(:header_dir).returns('Sub_dir')
+          header_search_paths = @pod_target.header_search_paths
+          header_search_paths.sort.should == [
+            '${PODS_ROOT}/Headers/Private/BananaLib',
+            '${PODS_ROOT}/Headers/Public',
+            '${PODS_ROOT}/Headers/Public/monkey',
+          ]
+        end
+
         it 'returns the correct header search paths recursively for dependent targets excluding platform' do
           @pod_target.build_headers.add_search_path('BananaLib', Platform.ios)
           @pod_target.sandbox.public_headers.add_search_path('BananaLib', Platform.ios)