[PodTargetInstaller] Generate module maps that exclude other target’s umbrella headers

This allows us to avoid incomplete umbrella header warnings

lib/cocoapods/installer/xcode/pods_project_generator.rb

@@ -165,8 +165,14 @@ module Pod
 
         def install_libraries
           UI.message '- Installing targets' do
+            umbrella_headers_by_dir = pod_targets.map do |pod_target|
+              next unless pod_target.should_build? && pod_target.defines_module?
+              pod_target.umbrella_header_path
+            end.compact.group_by(&:dirname)
+
             pod_targets.sort_by(&:name).each do |pod_target|
               target_installer = PodTargetInstaller.new(sandbox, pod_target)
+              target_installer.umbrella_headers_by_dir = umbrella_headers_by_dir
               target_installer.install!
             end
 

lib/cocoapods/installer/xcode/pods_project_generator/pod_target_installer.rb

@@ -29,7 +29,9 @@ module Pod
               create_test_xcconfig_files if target.contains_test_specifications?
               # TODO: determine if it is safe to unconditionally create (& 'link') module maps & umbrella
               #       headers for _all_ static libraries -- we've caused bugs by trying to do this in the past
-              create_module_map
+              create_module_map do |generator|
+                generator.headers.concat module_map_additional_headers
+              end
               create_umbrella_header do |generator|
                 file_accessors = target.file_accessors
                 file_accessors = file_accessors.reject { |f| f.spec.test_specification? } if target.contains_test_specifications?
@@ -68,6 +70,11 @@ module Pod
             end
           end
 
+          # @return [Hash<Pathname,Pathname>] A hash of all umbrella headers, grouped by the directory
+          #         the are stored in
+          #
+          attr_accessor :umbrella_headers_by_dir
+
           private
 
           # @param [Array<Specification>] specs
@@ -630,6 +637,17 @@ module Pod
             end
           end
 
+          def module_map_additional_headers
+            return [] unless umbrella_headers_by_dir
+
+            other_paths = umbrella_headers_by_dir[target.module_map_path.dirname] - [target.umbrella_header_path]
+            other_paths.map do |module_map_path|
+              # exclude other targets umbrella headers, to avoid
+              # incomplete umbrella warnings
+              Generator::ModuleMap::Header.new(module_map_path.basename, nil, nil, nil, true)
+            end
+          end
+
           def create_umbrella_header
             return super unless custom_module_map
           end