Dispose of loaded assembly definitions

Not disposing of the assembly definitions leads to file access
exceptions.

This is not causing any issues today since there is nothing that runs
the linker multiple times within the same process.

However, the new test framework does, and the lack of assembly def
disposal leads to file access exceptions during all tests after the
first.

3 files changed, 106 insertions, 91 deletions

diff --git a/linker/Mono.Linker/AssemblyResolver.cs b/linker/Mono.Linker/AssemblyResolver.cs
index df8af103b..169d06f98 100644
--- a/linker/Mono.Linker/AssemblyResolver.cs
+++ b/linker/Mono.Linker/AssemblyResolver.cs
@@ -71,5 +71,14 @@ namespace Mono.Linker {
 			_assemblies [assembly.Name.Name] = assembly;
 			base.AddSearchDirectory (Path.GetDirectoryName (assembly.MainModule.FileName));
 		}
+
+		protected override void Dispose (bool disposing)
+		{
+			foreach (var asm in _assemblies.Values) {
+				asm.Dispose ();
+			}
+
+			_assemblies.Clear ();
+		}
 	}
 }
diff --git a/linker/Mono.Linker/Driver.cs b/linker/Mono.Linker/Driver.cs
index 141922a47..6d2bcb769 100644
--- a/linker/Mono.Linker/Driver.cs
+++ b/linker/Mono.Linker/Driver.cs
@@ -77,109 +77,110 @@ namespace Mono.Linker {
 		void Run ()
 		{
 			Pipeline p = GetStandardPipeline ();
-			LinkContext context = GetDefaultContext (p);
-			I18nAssemblies assemblies = I18nAssemblies.All;
-			var custom_steps = new List<string> ();
-
-			bool resolver = false;
-			while (HaveMoreTokens ()) {
-				string token = GetParam ();
-				if (token.Length < 2)
-					Usage ("Option is too short");
-
-				if (! (token [0] == '-' || token [1] == '/'))
-					Usage ("Expecting an option, got instead: " + token);
-
-				if (token [0] == '-' && token [1] == '-') {
-
-					if (token.Length < 3)
+			using (LinkContext context = GetDefaultContext (p)) {
+				I18nAssemblies assemblies = I18nAssemblies.All;
+				var custom_steps = new List<string> ();
+
+				bool resolver = false;
+				while (HaveMoreTokens ()) {
+					string token = GetParam ();
+					if (token.Length < 2)
 						Usage ("Option is too short");
 
-					switch (token [2]) {
-					case 'v':
-						Version ();
+					if (!(token [0] == '-' || token [1] == '/'))
+						Usage ("Expecting an option, got instead: " + token);
+
+					if (token [0] == '-' && token [1] == '-') {
+
+						if (token.Length < 3)
+							Usage ("Option is too short");
+
+						switch (token [2]) {
+						case 'v':
+							Version ();
+							break;
+						case 'a':
+							About ();
+							break;
+						default:
+							Usage (null);
+							break;
+						}
+					}
+
+					switch (token [1]) {
+					case 'd': {
+						DirectoryInfo info = new DirectoryInfo (GetParam ());
+						context.Resolver.AddSearchDirectory (info.FullName);
 						break;
+					}
+					case 'o':
+						context.OutputDirectory = GetParam ();
+						break;
+					case 'c':
+						context.CoreAction = ParseAssemblyAction (GetParam ());
+						break;
+					case 'p':
+						AssemblyAction action = ParseAssemblyAction (GetParam ());
+						context.Actions [GetParam ()] = action;
+						break;
+					case 's':
+						custom_steps.Add (GetParam ());
+						break;
+					case 't':
+						context.KeepTypeForwarderOnlyAssemblies = true;
+						break;
+					case 'x':
+						foreach (string file in GetFiles (GetParam ()))
+							p.PrependStep (new ResolveFromXmlStep (new XPathDocument (file)));
+						resolver = true;
+						break;
+					case 'r':
 					case 'a':
-						About ();
+						var rootVisibility = (token [1] == 'r')
+							? ResolveFromAssemblyStep.RootVisibility.PublicAndFamily
+							: ResolveFromAssemblyStep.RootVisibility.Any;
+						foreach (string file in GetFiles (GetParam ()))
+							p.PrependStep (new ResolveFromAssemblyStep (file, rootVisibility));
+						resolver = true;
+						break;
+					case 'i':
+						foreach (string file in GetFiles (GetParam ()))
+							p.PrependStep (new ResolveFromXApiStep (new XPathDocument (file)));
+						resolver = true;
+						break;
+					case 'l':
+						assemblies = ParseI18n (GetParam ());
+						break;
+					case 'm':
+						context.SetParameter (GetParam (), GetParam ());
+						break;
+					case 'b':
+						context.LinkSymbols = bool.Parse (GetParam ());
+						break;
+					case 'g':
+						if (!bool.Parse (GetParam ()))
+							p.RemoveStep (typeof (RegenerateGuidStep));
+						break;
+					case 'v':
+						context.KeepMembersForDebuggerAttributes = bool.Parse (GetParam ());
 						break;
 					default:
-						Usage (null);
+						Usage ("Unknown option: `" + token [1] + "'");
 						break;
 					}
 				}
 
-				switch (token [1]) {
-				case 'd': {
-					DirectoryInfo info = new DirectoryInfo (GetParam ());
-					context.Resolver.AddSearchDirectory (info.FullName);
-					break;
-				}
-				case 'o':
-					context.OutputDirectory = GetParam ();
-					break;
-				case 'c':
-					context.CoreAction = ParseAssemblyAction (GetParam ());
-					break;
-				case 'p':
-					AssemblyAction action = ParseAssemblyAction (GetParam ());
-					context.Actions [GetParam ()] = action;
-					break;
-				case 's':
-					custom_steps.Add (GetParam ());
-					break;
-				case 't':
-					context.KeepTypeForwarderOnlyAssemblies = true;
-					break;
-				case 'x':
-					foreach (string file in GetFiles (GetParam ()))
-						p.PrependStep (new ResolveFromXmlStep (new XPathDocument (file)));
-					resolver = true;
-					break;
-				case 'r':
-				case 'a':
-					var rootVisibility = (token[1] == 'r')
-							? ResolveFromAssemblyStep.RootVisibility.PublicAndFamily
-							: ResolveFromAssemblyStep.RootVisibility.Any;
-					foreach (string file in GetFiles (GetParam ()))
-						p.PrependStep (new ResolveFromAssemblyStep (file, rootVisibility));
-					resolver = true;
-					break;
-				case 'i':
-					foreach (string file in GetFiles (GetParam ()))
-						p.PrependStep (new ResolveFromXApiStep (new XPathDocument (file)));
-					resolver = true;
-					break;
-				case 'l':
-					assemblies = ParseI18n (GetParam ());
-					break;
-				case 'm':
-					context.SetParameter (GetParam (), GetParam ());
-					break;
-				case 'b':
-					context.LinkSymbols = bool.Parse (GetParam ());
-					break;
-				case 'g':
-					if (!bool.Parse (GetParam ()))
-						p.RemoveStep (typeof (RegenerateGuidStep));
-					break;
-				case 'v':
-					context.KeepMembersForDebuggerAttributes = bool.Parse (GetParam ());
-					break;
-				default:
-					Usage ("Unknown option: `" + token [1] + "'");
-					break;
-				}
-			}
-
-			if (!resolver)
-				Usage ("No resolver was created (use -x, -a or -i)");
+				if (!resolver)
+					Usage ("No resolver was created (use -x, -a or -i)");
 
-			foreach (string custom_step in custom_steps)
-				AddCustomStep (p, custom_step);
+				foreach (string custom_step in custom_steps)
+					AddCustomStep (p, custom_step);
 
-			p.AddStepAfter (typeof (LoadReferencesStep), new LoadI18nAssemblies (assemblies));
+				p.AddStepAfter (typeof (LoadReferencesStep), new LoadI18nAssemblies (assemblies));
 
-			p.Process (context);
+				p.Process (context);
+			}
 		}
 
 		protected static void AddCustomStep (Pipeline pipeline, string arg)
diff --git a/linker/Mono.Linker/LinkContext.cs b/linker/Mono.Linker/LinkContext.cs
index dbb0b7f44..6a4ae5d8d 100644
--- a/linker/Mono.Linker/LinkContext.cs
+++ b/linker/Mono.Linker/LinkContext.cs
@@ -34,7 +34,7 @@ using Mono.Cecil.Cil;
 
 namespace Mono.Linker {
 
-	public class LinkContext {
+	public class LinkContext : IDisposable {
 
 		Pipeline _pipeline;
 		AssemblyAction _coreAction;
@@ -296,5 +296,10 @@ namespace Mono.Linker {
 			_parameters.TryGetValue (key, out val);
 			return val;
 		}
+
+		public void Dispose ()
+		{
+			_resolver.Dispose ();
+		}
 	}
 }