#17923: Modules from ~/Bin and ~/Core have higher priority

Because of the way ASP.NET BuildManager works(*), we can't enable
dynamic compilation of a module if the module is already
present in ~/bin.

(*) When invoking the compiler, BuildManager automatically adds
references to all assemblies present in ~/bin. So, if you have module
"X" in "~/bin", there is no way to enable dynamic compilation of
module "X" by compiling "X.csproj", as there will be tons of
compilation errors with equivalent types defined in multiple
assemblies.

--HG--
branch : 1.x

src/Orchard/Environment/Extensions/ExtensionLoaderCoordinator.cs

@@ -247,7 +247,20 @@ namespace Orchard.Environment.Extensions {
         }
 
         private IEnumerable<ExtensionProbeEntry> SortExtensionProbeEntries(IEnumerable<ExtensionProbeEntry> entries, ConcurrentDictionary<string, DateTime> virtualPathModficationDates) {
-            return entries
+            // All "entries" are for the same extension ID, so we just need to filter/sort them by priority+ modification dates.
+            var groupByPriority = entries
+                .GroupBy(entry => entry.Priority)
+                .OrderByDescending(g => g.Key);
+
+            // Select highest priority group with at least one item
+            var firstNonEmptyGroup = groupByPriority.FirstOrDefault(g => g.Count() >= 1) ?? Enumerable.Empty<ExtensionProbeEntry>();
+
+            // No need for further sorting if only 1 item found
+            if (firstNonEmptyGroup.Count() <= 1)
+                return firstNonEmptyGroup;
+
+            // Sort by last modification date/loader order
+            return firstNonEmptyGroup
                 .OrderByDescending(probe => GetVirtualPathDepedenciesModificationTimeUtc(virtualPathModficationDates, probe))
                 .ThenBy(probe => probe.Loader.Order)
                 .ToList();

src/Orchard/Environment/Extensions/Loaders/CoreExtensionLoader.cs

@@ -32,6 +32,7 @@ namespace Orchard.Environment.Extensions.Loaders {
                 return new ExtensionProbeEntry {
                     Descriptor = descriptor,
                     Loader = this,
+                    Priority = 100, // Higher priority because assemblies in ~/bin always take precedence
                     VirtualPath = "~/Core/" + descriptor.Id,
                     VirtualPathDependencies = Enumerable.Empty<string>(),
                 };

src/Orchard/Environment/Extensions/Loaders/IExtensionLoader.cs

@@ -9,6 +9,7 @@ namespace Orchard.Environment.Extensions.Loaders {
     public class ExtensionProbeEntry {
         public ExtensionDescriptor Descriptor { get; set; }
         public IExtensionLoader Loader { get; set; }
+        public int Priority { get; set; }
         public string VirtualPath { get; set; }
         public IEnumerable<string> VirtualPathDependencies { get; set; }
     }

src/Orchard/Environment/Extensions/Loaders/ReferencedExtensionLoader.cs

@@ -1,4 +1,5 @@
-using System.IO;
+using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using Orchard.Environment.Extensions.Models;
 using Orchard.FileSystems.Dependencies;
@@ -59,6 +60,7 @@ namespace Orchard.Environment.Extensions.Loaders {
             return new ExtensionProbeEntry {
                 Descriptor = descriptor,
                 Loader = this,
+                Priority = 100, // Higher priority because assemblies in ~/bin always take precedence
                 VirtualPath = assemblyPath,
                 VirtualPathDependencies = new[] { assemblyPath },
             };