Add check to Xcode action to prevent multiple target kinds per project (not supported by Xcode)

src/actions/xcode/_xcode.lua

@@ -39,4 +39,15 @@
 		oncleanproject = function(prj)
 			premake.clean.directory(prj, "%%.xcodeproj")
 		end,
+		
+		oncheckproject = function(prj)
+			-- Xcode can't mix target kinds within a project
+			local last
+			for cfg in premake.eachconfig(prj) do
+				if last and last ~= cfg.kind then
+					error("Project '" .. prj.name .. "' uses more than one target kind; not supported by Xcode", 0)
+				end
+				last = cfg.kind
+			end
+		end,
 	}

src/base/validate.lua

@@ -6,7 +6,7 @@
 
 
 --
--- Performs a sanity check all all of the solutions and projects 
+-- Performs a sanity check of all of the solutions and projects 
 -- in the session to be sure they meet some minimum requirements.
 --
 
@@ -54,6 +54,12 @@
 					end
 					
 				end
+				
+				-- some actions have custom validation logic
+				if action.oncheckproject then
+					action.oncheckproject(prj)
+				end
+				
 			end
 		end		
 		return true