Separate storing underlying types in delegates from property map underlying types.

Author: BlaiseD

Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <Authors>Jimmy Bogard</Authors>
     <LangVersion>latest</LangVersion>
-    <VersionPrefix>1.0.5-preview01</VersionPrefix>
+    <VersionPrefix>1.0.5-preview02</VersionPrefix>
     <WarningsAsErrors>true</WarningsAsErrors>
     <NoWarn>$(NoWarn);1701;1702;1591</NoWarn>
   </PropertyGroup>

src/AutoMapper.Extensions.ExpressionMapping/MapperExtensions.cs

@@ -256,7 +256,7 @@ private static Dictionary<Type, Type> AddTypeMappingsFromDelegates(this Dictiona
             if (typeMappings == null)
                 throw new ArgumentException(Resource.typeMappingsDictionaryIsNull);
 
-            typeMappings.DoAddTypeMappings
+            typeMappings.DoAddTypeMappingsFromDelegates
             (
                 configurationProvider,
                 sourceType.GetGenericArguments().ToList(),
@@ -266,7 +266,7 @@ private static Dictionary<Type, Type> AddTypeMappingsFromDelegates(this Dictiona
             return typeMappings;
         }
 
-        private static void DoAddTypeMappings(this Dictionary<Type, Type> typeMappings, IConfigurationProvider configurationProvider, List<Type> sourceArguments, List<Type> destArguments)
+        private static void DoAddTypeMappingsFromDelegates(this Dictionary<Type, Type> typeMappings, IConfigurationProvider configurationProvider, List<Type> sourceArguments, List<Type> destArguments)
         {
             if (sourceArguments.Count != destArguments.Count)
                 throw new ArgumentException(Resource.invalidArgumentCount);
@@ -278,6 +278,18 @@ private static void DoAddTypeMappings(this Dictionary<Type, Type> typeMappings,
             }
         }
 
+        private static void DoAddTypeMappings(this Dictionary<Type, Type> typeMappings, IConfigurationProvider configurationProvider, List<Type> sourceArguments, List<Type> destArguments)
+        {
+            if (sourceArguments.Count != destArguments.Count)
+                return;
+
+            for (int i = 0; i < sourceArguments.Count; i++)
+            {
+                if (!typeMappings.ContainsKey(sourceArguments[i]) && sourceArguments[i] != destArguments[i])
+                    typeMappings.AddTypeMapping(configurationProvider, sourceArguments[i], destArguments[i]);
+            }
+        }
+
         private static void FindChildPropertyTypeMaps(this Dictionary<Type, Type> typeMappings, IConfigurationProvider ConfigurationProvider, Type source, Type dest)
         {
             //The destination becomes the source because to map a source expression to a destination expression,