[PodTarget] Only create module maps for targets that define a module

By default, targets integrated as static libraries _will not_ get a module map, unless they opt-in by including `DEFINES_MODULE = YES` in their specification's `pod_target_xcconfig`

lib/cocoapods/generator/xcconfig/xcconfig_helper.rb

@@ -339,13 +339,15 @@ module Pod
                 framework_search_paths << dependent_target.configuration_build_dir(CONFIGURATION_BUILD_DIR_VARIABLE)
               else
                 library_search_paths << dependent_target.configuration_build_dir(CONFIGURATION_BUILD_DIR_VARIABLE)
-                module_map_file = if dependent_target.uses_swift?
-                                    # for swift, we have a custom build phase that copies in the module map, appending the .Swift module
-                                    "${PODS_CONFIGURATION_BUILD_DIR}/#{dependent_target.label}/#{dependent_target.product_module_name}.modulemap"
-                                  else
-                                    "${PODS_ROOT}/#{dependent_target.module_map_path.relative_path_from(dependent_target.sandbox.root)}"
-                                  end
-                module_map_files << %(-fmodule-map-file="#{module_map_file}")
+                if dependent_target.defines_module?
+                  module_map_file = if dependent_target.uses_swift?
+                                      # for swift, we have a custom build phase that copies in the module map, appending the .Swift module
+                                      "${PODS_CONFIGURATION_BUILD_DIR}/#{dependent_target.label}/#{dependent_target.product_module_name}.modulemap"
+                                    else
+                                      "${PODS_ROOT}/#{dependent_target.module_map_path.relative_path_from(dependent_target.sandbox.root)}"
+                                    end
+                  module_map_files << %(-fmodule-map-file="#{module_map_file}")
+                end
               end
               swift_import_paths << dependent_target.configuration_build_dir(CONFIGURATION_BUILD_DIR_VARIABLE)
             end
@@ -356,7 +358,7 @@ module Pod
           end
 
           other_swift_flags = module_map_files.tap(&:uniq!).flat_map { |f| ['-Xcc', f] }
-          if target.is_a?(PodTarget) && !target.requires_frameworks?
+          if target.is_a?(PodTarget) && !target.requires_frameworks? && target.defines_module?
             # make it possible for a mixed swift/objc static library to be able to import the objc from within swift
             other_swift_flags += ['-import-underlying-module', '-Xcc', '-fmodule-map-file="${SRCROOT}/${MODULEMAP_FILE}"']
           end

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

@@ -27,22 +27,24 @@ module Pod
               add_files_to_build_phases
               create_xcconfig_file
               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 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?
-                generator.imports += if header_mappings_dir
-                                       file_accessors.flat_map(&:public_headers).map do |pathname|
-                                         pathname.relative_path_from(header_mappings_dir)
-                                       end
-                                     else
-                                       file_accessors.flat_map(&:public_headers).map(&:basename)
-                                     end
+
+              if target.defines_module?
+                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?
+                  generator.imports += if header_mappings_dir
+                                         file_accessors.flat_map(&:public_headers).map do |pathname|
+                                           pathname.relative_path_from(header_mappings_dir)
+                                         end
+                                       else
+                                         file_accessors.flat_map(&:public_headers).map(&:basename)
+                                      end
+                end
               end
+
               if target.requires_frameworks?
                 unless target.static_framework?
                   create_info_plist_file(target.info_plist_path, native_target, target.version, target.platform)
@@ -54,6 +56,7 @@ module Pod
               elsif target.uses_swift?
                 add_swift_static_library_compatibility_header_phase
               end
+
               unless skip_pch?(target.non_test_specs)
                 path = target.prefix_header_path
                 file_accessors = target.file_accessors.reject { |f| f.spec.test_specification? }

spec/unit/generator/xcconfig/aggregate_xcconfig_spec.rb

@@ -146,6 +146,13 @@ module Pod
           end
 
           it 'adds the sandbox public headers search paths to the xcconfig, with quotes, as system headers' do
+            expected = "$(inherited) -isystem \"#{config.sandbox.public_headers.search_paths(Platform.ios).join('" -isystem "')}\""
+            @xcconfig.to_hash['OTHER_CFLAGS'].should == expected
+          end
+
+          it 'adds the dependent pods module map file to OTHER_CFLAGS' do
+            @pod_targets.each { |pt| pt.stubs(:defines_module? => true) }
+            @xcconfig = @generator.generate
             expected = '$(inherited) -fmodule-map-file="${PODS_ROOT}/Headers/Private/BananaLib/BananaLib.modulemap" -isystem "${PODS_ROOT}/Headers/Public/BananaLib"'
             @xcconfig.to_hash['OTHER_CFLAGS'].should == expected
           end

spec/unit/installer/xcode/pods_project_generator/pod_target_installer_spec.rb

@@ -478,7 +478,6 @@ module Pod
                 group.children.map(&:display_name).sort.should == [
                   'BananaLib-Pods-SampleProject-dummy.m',
                   'BananaLib-Pods-SampleProject-prefix.pch',
-                  'BananaLib-Pods-SampleProject.modulemap',
                   'BananaLib-Pods-SampleProject.xcconfig',
                 ]
               end
@@ -490,7 +489,6 @@ module Pod
                 group.children.map(&:display_name).sort.should == [
                   'BananaLib-Pods-SampleProject-dummy.m',
                   'BananaLib-Pods-SampleProject-prefix.pch',
-                  'BananaLib-Pods-SampleProject.modulemap',
                   'BananaLib-Pods-SampleProject.xcconfig',
                 ]
               end
@@ -501,6 +499,17 @@ module Pod
                 group = @project['Pods/BananaLib/Support Files']
                 group.children.map(&:display_name).sort.should == [
                   'BananaLib-Pods-SampleProject-dummy.m',
+                  'BananaLib-Pods-SampleProject.xcconfig',
+                ]
+              end
+
+              it 'adds the module map when the target defines a module' do
+                @pod_target.stubs(:defines_module?).returns(true)
+                @installer.install!
+                group = @project['Pods/BananaLib/Support Files']
+                group.children.map(&:display_name).sort.should == [
+                  'BananaLib-Pods-SampleProject-dummy.m',
+                  'BananaLib-Pods-SampleProject-prefix.pch',
                   'BananaLib-Pods-SampleProject.modulemap',
                   'BananaLib-Pods-SampleProject.xcconfig',
                 ]
@@ -570,7 +579,6 @@ module Pod
                 group.children.map(&:display_name).sort.should == [
                   'BananaLib-dummy.m',
                   'BananaLib-prefix.pch',
-                  'BananaLib.modulemap',
                   'BananaLib.xcconfig',
                 ]
               end
@@ -581,6 +589,17 @@ module Pod
                 group = @project['Pods/BananaLib/Support Files']
                 group.children.map(&:display_name).sort.should == [
                   'BananaLib-dummy.m',
+                  'BananaLib.xcconfig',
+                ]
+              end
+
+              it 'adds the module map when the target defines a module' do
+                @pod_target.stubs(:defines_module?).returns(true)
+                @installer.install!
+                group = @project['Pods/BananaLib/Support Files']
+                group.children.map(&:display_name).sort.should == [
+                  'BananaLib-dummy.m',
+                  'BananaLib-prefix.pch',
                   'BananaLib.modulemap',
                   'BananaLib.xcconfig',
                 ]