[Analyzer] Only warn when there is a minimum deployment target mismatch

CHANGELOG.md

@@ -17,6 +17,11 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   `pod repo list`.  
   [Kyle Fuller](https://github.com/kylef)
 
+* Only show a warning when there is a minimum deployment target mismatch
+  between target and spec, instead of throwing a hard error.  
+  [Samuel Giddins](https://github.com/segiddins)
+  [#1241](https://github.com/CocoaPods/CocoaPods/issues/1241)
+
 ##### Bug Fixes
 
 * Do not pass code-sign arguments to xcodebuild when linting OS X targets.  

lib/cocoapods/installer/analyzer.rb

@@ -55,7 +55,7 @@ module Pod
 
         store_existing_checkout_options
         fetch_external_sources if allow_fetches
-        @result.specs_by_target = resolve_dependencies
+        @result.specs_by_target = validate_platforms(resolve_dependencies)
         @result.specifications  = generate_specifications
         @result.targets         = generate_targets
         @result.sandbox_state   = generate_sandbox_state
@@ -431,6 +431,26 @@ module Pod
         specs_by_target
       end
 
+      # Warns for any specification that is incompatible with its target.
+      #
+      # @param  [Hash{TargetDefinition => Array<Spec>}] specs_by_target
+      #         the specifications grouped by target.
+      #
+      # @return [Hash{TargetDefinition => Array<Spec>}] the specifications
+      #         grouped by target.
+      #
+      def validate_platforms(specs_by_target)
+        specs_by_target.each do |target, specs|
+          specs.each do |spec|
+            unless spec.available_platforms.any? { |p| target.platform.supports?(p) }
+              UI.warn "The platform of the target `#{target.name}` "     \
+                "(#{target.platform}) may not be compatible with `#{spec}` which has "  \
+                "a minimum requirement of #{spec.available_platforms.join(' - ')}."
+            end
+          end
+        end
+      end
+
       # Returns the list of all the resolved the resolved specifications.
       #
       # @return [Array<Specification>] the list of the specifications.

lib/cocoapods/resolver.rb

@@ -355,16 +355,13 @@ module Pod
     #
     # @raise  If the specification is not supported by the target.
     #
-    # @todo   This step is not specific to the resolution process and should be
-    #         performed later in the analysis.
-    #
     # @return [void]
     #
     def validate_platform(spec, target)
-      unless spec.available_platforms.any? { |p| target.platform.supports?(p) }
+      unless spec.available_platforms.any? { |p| target.platform.to_sym == p.to_sym }
         raise Informative, "The platform of the target `#{target.name}` "     \
-          "(#{target.platform}) is not compatible with `#{spec}` which has "  \
-          "a minimum requirement of #{spec.available_platforms.join(' - ')}."
+          "(#{target.platform}) is not compatible with `#{spec}`, which does "  \
+          "not support `#{target.platform.name}`."
       end
     end
 

spec/unit/installer/analyzer_spec.rb

@@ -271,6 +271,12 @@ module Pod
         ]
       end
 
+      it 'warns once any of the dependencies does not match the platform of its podfile target' do
+        Specification.any_instance.stubs(:available_platforms).returns([Platform.new(:ios, '999')])
+        @analyzer.analyze
+        UI.warnings.should.match(/platform .* may not be compatible/)
+      end
+
       xit 'removes the specifications of the changed pods to prevent confusion in the resolution process' do
         @analyzer.allow_pre_downloads = true
         podspec = @analyzer.sandbox.root + 'Local Podspecs/JSONKit.podspec'

spec/unit/resolver_spec.rb

@@ -169,12 +169,6 @@ module Pod
         ].sort_by(&:name)
       end
 
-      it 'raises once any of the dependencies does not match the platform of its podfile target' do
-        Specification.any_instance.stubs(:available_platforms).returns([Platform.new(:ios, '999')])
-        e = lambda { @resolver.resolve }.should.raise Informative
-        e.message.should.match(/platform .* not compatible/)
-      end
-
       it 'raises when a resolved dependency has a platform incompatibility' do
         @podfile = Podfile.new do
           platform :osx, '10.7'