Require explicit use of `use_frameworks!`

lib/cocoapods/installer.rb

@@ -92,6 +92,7 @@ module Pod
       determine_dependency_product_types
       verify_no_duplicate_framework_names
       verify_no_static_framework_transitive_dependencies
+      verify_framework_usage
       generate_pods_project
       integrate_user_project if config.integrate_targets?
       perform_post_install_actions
@@ -369,6 +370,22 @@ module Pod
       end
     end
 
+    def verify_framework_usage
+      aggregate_targets.each do |aggregate_target|
+        next if aggregate_target.requires_frameworks?
+
+        aggregate_target.user_build_configurations.keys.each do |config|
+          pod_targets = aggregate_target.pod_targets_for_build_configuration(config)
+
+          if pod_targets.any?(&:uses_swift?)
+            raise Informative, 'Pods written in Swift can only be integrated as frameworks; this ' \
+              'feature is still in beta. Add `use_frameworks!` to your Podfile or target to opt ' \
+              'in to using it.'
+          end
+        end
+      end
+    end
+
     # Performs any post-installation actions
     #
     # @return [void]

lib/cocoapods/target.rb

@@ -91,13 +91,8 @@ module Pod
     # @return [Boolean] whether the generated target needs to be implemented
     #         as a framework
     #
-    # @note This applies either if Swift was used by the host, which was checked
-    #       eagerly by the analyzer before, or in the given target or its
-    #       dependents, which can only be checked after the specs were been
-    #       fetched.
-    #
     def requires_frameworks?
-      host_requires_frameworks? || uses_swift?
+      host_requires_frameworks? || false
     end
 
     #-------------------------------------------------------------------------#

spec/unit/generator/xcconfig/aggregate_xcconfig_spec.rb

@@ -123,6 +123,10 @@ module Pod
             fixture_spec('orange-framework/OrangeFramework.podspec')
           end
 
+          before do
+            Target.any_instance.stubs(:requires_frameworks?).returns(true)
+          end
+
           behaves_like 'AggregateXCConfig'
 
           it 'sets the PODS_FRAMEWORK_BUILD_PATH build variable' do

spec/unit/installer_spec.rb

@@ -51,6 +51,7 @@ module Pod
         @installer.stubs(:determine_dependency_product_types)
         @installer.stubs(:verify_no_duplicate_framework_names)
         @installer.stubs(:verify_no_static_framework_transitive_dependencies)
+        @installer.stubs(:verify_framework_usage)
         @installer.stubs(:generate_pods_project)
         @installer.stubs(:integrate_user_project)
         @installer.stubs(:run_plugins_post_install_hooks)
@@ -125,6 +126,7 @@ module Pod
         podfile = Pod::Podfile.new do
           platform :ios, '8.0'
           xcodeproj 'SampleProject/SampleProject'
+          use_frameworks!
           pod 'BananaLib',       :path => (fixture_path + 'banana-lib').to_s
           pod 'OrangeFramework', :path => (fixture_path + 'orange-framework').to_s
           pod 'monkey',          :path => (fixture_path + 'monkey').to_s
@@ -177,6 +179,7 @@ module Pod
         podfile = Pod::Podfile.new do
           platform :ios, '8.0'
           xcodeproj 'SampleProject/SampleProject'
+          use_frameworks!
           pod 'BananaLib',       :path => (fixture_path + 'banana-lib').to_s
           pod 'OrangeFramework', :path => (fixture_path + 'orange-framework').to_s
           pod 'monkey',          :path => (fixture_path + 'monkey').to_s

spec/unit/target/aggregate_target_spec.rb

@@ -202,6 +202,7 @@ module Pod
         before do
           @pod_target = fixture_pod_target('orange-framework/OrangeFramework.podspec', :ios, Podfile::TargetDefinition.new('iOS Example', nil))
           @target = AggregateTarget.new(@pod_target.target_definition, config.sandbox)
+          @target.stubs(:requires_frameworks?).returns(true)
           @target.pod_targets = [@pod_target]
         end
 

spec/unit/target/pod_target_spec.rb

@@ -178,6 +178,7 @@ module Pod
       describe 'With frameworks' do
         before do
           @pod_target = fixture_pod_target('orange-framework/OrangeFramework.podspec')
+          @pod_target.host_requires_frameworks = true
         end
 
         it 'returns that it uses swift' do

spec/unit/validator_spec.rb

@@ -448,6 +448,7 @@ module Pod
         podspec.gsub!(/.*license.*$/, '"license": "Public Domain",')
         file = write_podspec(podspec)
 
+        Podfile::TargetDefinition.any_instance.stubs(:uses_frameworks?).returns(true)
         Pod::Sandbox::FileAccessor.any_instance.stubs(:source_files).returns([Pathname.new('/Foo.swift')])
         validator = Validator.new(file, SourcesManager.master.map(&:url))
         validator.stubs(:build_pod)