[Core] Support facade assemblies from a custom location

Added a OnGetFacadeAssemblies method to the DotNetProjectExtension
that allows a project extension to provide the facade assemblies
for a project if the default behaviour does not work for the project.
This can be used by the Xamarin.Mac project extension to provide
the facade assemblies when the project uses Xamarin.Mac full. A
Xamarin.Mac full project will use a custom facades directory at
build time but the project has a target framework of .NET Framework
so the default facades assembly resolution logic will return the
wrong facade assemblies that are included with Mono.

2 files changed, 32 insertions, 8 deletions

diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs
index 07b2ca1735..8186af470c 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProject.cs
@@ -972,19 +972,33 @@ namespace MonoDevelop.Projects
 			}
 
 			if (addFacadeAssemblies) {
-				var runtime = TargetRuntime ?? MonoDevelop.Core.Runtime.SystemAssemblyService.DefaultRuntime;
-				var facades = runtime.FindFacadeAssembliesForPCL (TargetFramework);
-				foreach (var facade in facades) {
-					if (!File.Exists (facade))
-						continue;
-					var ar = new AssemblyReference (facade);
-					if (!result.Contains (ar))
-						result.Add (ar);
+				var facades = await ProjectExtension.OnGetFacadeAssemblies ();
+				if (facades != null) {
+					foreach (var facade in facades) {
+						if (!result.Contains (facade))
+							result.Add (facade);
+					}
 				}
 			}
 			return result;
 		}
 
+		internal protected virtual Task<List<AssemblyReference>> OnGetFacadeAssemblies ()
+		{
+			List<AssemblyReference> result = null;
+			var runtime = TargetRuntime ?? Runtime.SystemAssemblyService.DefaultRuntime;
+			var facades = runtime.FindFacadeAssembliesForPCL (TargetFramework);
+			foreach (var facade in facades) {
+				if (!File.Exists (facade))
+					continue;
+				if (result == null)
+					result = new List<AssemblyReference> ();
+				var ar = new AssemblyReference (facade);
+				result.Add (ar);
+			}
+			return Task.FromResult (result);
+		}
+
 		AsyncCriticalSection referenceCacheLock = new AsyncCriticalSection ();
 		ImmutableDictionary<string, List<AssemblyReference>> referenceCache = ImmutableDictionary<string, List<AssemblyReference>>.Empty;
 		bool referenceCacheNeedsRefresh;
@@ -2030,6 +2044,11 @@ namespace MonoDevelop.Projects
 				return Project.OnGetReferencedAssemblyProjects (configuration);
 			}
 
+			internal protected override Task<List<AssemblyReference>> OnGetFacadeAssemblies ()
+			{
+				return Project.OnGetFacadeAssemblies ();
+			}
+
 #pragma warning disable 672 // Member overrides obsolete member
 			internal protected override ExecutionCommand OnCreateExecutionCommand (ConfigurationSelector configSel, DotNetProjectConfiguration configuration)
 			{
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProjectExtension.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProjectExtension.cs
index 3737d95c64..62106c0508 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProjectExtension.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/DotNetProjectExtension.cs
@@ -88,6 +88,11 @@ namespace MonoDevelop.Projects
 			return next.OnGetReferencedAssemblyProjects (configuration);
 		}
 
+		internal protected virtual Task<List<AssemblyReference>> OnGetFacadeAssemblies ()
+		{
+			return next.OnGetFacadeAssemblies ();
+		}
+
 		[Obsolete("User overload that takes a RunConfiguration")]
 		internal protected virtual ExecutionCommand OnCreateExecutionCommand (ConfigurationSelector configSel, DotNetProjectConfiguration configuration)
 		{