[bcl] Dispose Cecil AssemblyDefinition after usage (#4900)

Follow-up to https://github.com/mono/mono/pull/4899. I audited
all the places in BCL where we made use of Cecil's AssemblyDefinition
and made sure we're properly disposing them and not keeping files
unnecessarily open.

I used InMemory=true in cases where tracking the lifetime would
be complicated. There are also some tests in mcs/tests which I
didn't bother to fix.

7 files changed, 116 insertions, 109 deletions

diff --git a/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Rewrite/Rewriter.cs b/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Rewrite/Rewriter.cs
index 5654252415d..66fb7f232c0 100644
--- a/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Rewrite/Rewriter.cs
+++ b/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Rewrite/Rewriter.cs
@@ -67,33 +67,34 @@ namespace Mono.CodeContracts.Rewrite {
 			if (options.Debug && options.WritePdbFile)
 				readerParameters.ReadSymbols = true;
 
-			var assembly = this.options.Assembly.IsFilename ?
+			using (var assembly = this.options.Assembly.IsFilename ?
 				AssemblyDefinition.ReadAssembly (options.Assembly.Filename, readerParameters) :
-				AssemblyDefinition.ReadAssembly (options.Assembly.Streams.Assembly, readerParameters);
+				AssemblyDefinition.ReadAssembly (options.Assembly.Streams.Assembly, readerParameters)) {
 			
-			if (this.options.ForceAssemblyRename != null) {
-				assembly.Name.Name = this.options.ForceAssemblyRename;
-			} else if (this.options.OutputFile.IsSet && this.options.OutputFile.IsFilename) {
-				assembly.Name.Name = Path.GetFileNameWithoutExtension(this.options.OutputFile.Filename);
-			}
+				if (this.options.ForceAssemblyRename != null) {
+					assembly.Name.Name = this.options.ForceAssemblyRename;
+				} else if (this.options.OutputFile.IsSet && this.options.OutputFile.IsFilename) {
+					assembly.Name.Name = Path.GetFileNameWithoutExtension(this.options.OutputFile.Filename);
+				}
 
-			var output = this.options.OutputFile.IsSet ? this.options.OutputFile : this.options.Assembly;
-			var writerParameters = new WriterParameters ();
-			if (options.WritePdbFile) {
-				if (!options.Debug) {
-					return RewriterResults.Error ("Must specify -debug if using -writePDBFile.");
+				var output = this.options.OutputFile.IsSet ? this.options.OutputFile : this.options.Assembly;
+				var writerParameters = new WriterParameters ();
+				if (options.WritePdbFile) {
+					if (!options.Debug) {
+						return RewriterResults.Error ("Must specify -debug if using -writePDBFile.");
+					}
+					
+					writerParameters.WriteSymbols = true;
 				}
 				
-				writerParameters.WriteSymbols = true;
-			}
-			
-			PerformRewrite rewriter = new PerformRewrite (this.options);
-			rewriter.Rewrite (assembly);
+				PerformRewrite rewriter = new PerformRewrite (this.options);
+				rewriter.Rewrite (assembly);
 
-			if (output.IsFilename) {
-				assembly.Write (output.Filename, writerParameters);
-			} else {
-				assembly.Write (output.Streams.Assembly, writerParameters);
+				if (output.IsFilename) {
+					assembly.Write (output.Filename, writerParameters);
+				} else {
+					assembly.Write (output.Streams.Assembly, writerParameters);
+				}
 			}
 		
 			return new RewriterResults (warnings, errors);
diff --git a/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.AST/AssemblyNode.cs b/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.AST/AssemblyNode.cs
index 04c7c6e0bac..adc51def4e2 100644
--- a/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.AST/AssemblyNode.cs
+++ b/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.AST/AssemblyNode.cs
@@ -72,7 +72,7 @@ namespace Mono.CodeContracts.Static.AST {
 
 		public static AssemblyNode ReadAssembly (string filename)
 		{
-			var readerParameters = new ReaderParameters ();
+			var readerParameters = new ReaderParameters () { InMemory = true };
 			AssemblyDefinition definition = AssemblyDefinition.ReadAssembly (filename, readerParameters);
 
 			return new AssemblyNode (definition);
diff --git a/mcs/tools/corcompare/AssemblyResolver.cs b/mcs/tools/corcompare/AssemblyResolver.cs
index 56000ca6777..063a688d47a 100644
--- a/mcs/tools/corcompare/AssemblyResolver.cs
+++ b/mcs/tools/corcompare/AssemblyResolver.cs
@@ -44,7 +44,7 @@ namespace GuiCompare {
 		AssemblyDefinition ProcessFile (string file)
 		{
 			AddSearchDirectory (Path.GetDirectoryName (file));
-			var assembly = AssemblyDefinition.ReadAssembly (file, new ReaderParameters { AssemblyResolver = this });
+			var assembly = AssemblyDefinition.ReadAssembly (file, new ReaderParameters { AssemblyResolver = this, InMemory = true });
 			RegisterAssembly (assembly);
 
 			return assembly;
diff --git a/mcs/tools/mdbdump/mdbdump.cs b/mcs/tools/mdbdump/mdbdump.cs
index 559bc2b9b3f..4042f07d6b1 100644
--- a/mcs/tools/mdbdump/mdbdump.cs
+++ b/mcs/tools/mdbdump/mdbdump.cs
@@ -15,10 +15,11 @@ public class MdbDump
 			return 1;
 		}
 
-		var assembly = AssemblyDefinition.ReadAssembly (args[0]);
+		using (var assembly = AssemblyDefinition.ReadAssembly (args[0])) {
 
-		var f = MonoSymbolFile.ReadSymbolFile (args[0] + ".mdb");
-		DumpSymbolFile (assembly, f, Console.Out);
+			var f = MonoSymbolFile.ReadSymbolFile (args[0] + ".mdb");
+			DumpSymbolFile (assembly, f, Console.Out);
+		}
 
 		return 0;
 	}
diff --git a/mcs/tools/mono-symbolicate/LocationProvider.cs b/mcs/tools/mono-symbolicate/LocationProvider.cs
index f03adfdee58..8a0f6ece91b 100644
--- a/mcs/tools/mono-symbolicate/LocationProvider.cs
+++ b/mcs/tools/mono-symbolicate/LocationProvider.cs
@@ -11,7 +11,7 @@ namespace Mono
 {
 	class AssemblyLocationProvider
 	{
-		AssemblyDefinition assembly;
+		string assemblyFullPath;
 		Logger logger;
 
 		public AssemblyLocationProvider (string assemblyPath, Logger logger)
@@ -22,85 +22,88 @@ namespace Mono
 			if (!File.Exists (assemblyPath))
 				throw new ArgumentException ("assemblyPath does not exist: "+ assemblyPath);
 
-			var readerParameters = new ReaderParameters { ReadSymbols = true };
-			assembly = AssemblyDefinition.ReadAssembly (assemblyPath, readerParameters);
+			assemblyFullPath = assemblyPath;
 		}
 
 		public bool TryResolveLocation (StackFrameData sfData, SeqPointInfo seqPointInfo)
 		{
-			if (!assembly.MainModule.HasSymbols)
-				return false;
+			var readerParameters = new ReaderParameters { ReadSymbols = true };
+			using (var assembly = AssemblyDefinition.ReadAssembly (assemblyFullPath, readerParameters)) {
 
-			TypeDefinition type = null;
-			string[] nested;
-			if (sfData.TypeFullName.IndexOf ('/') >= 0)
-				 nested = sfData.TypeFullName.Split ('/');
-			else
-				nested = sfData.TypeFullName.Split ('+');
-
-			var types = assembly.MainModule.Types;
-			foreach (var ntype in nested) {
-				if (type == null) {
-					// Use namespace first time.
-					type = types.FirstOrDefault (t => t.FullName == ntype);
-				} else {
-					type = types.FirstOrDefault (t => t.Name == ntype);
+				if (!assembly.MainModule.HasSymbols)
+					return false;
+
+				TypeDefinition type = null;
+				string[] nested;
+				if (sfData.TypeFullName.IndexOf ('/') >= 0)
+					nested = sfData.TypeFullName.Split ('/');
+				else
+					nested = sfData.TypeFullName.Split ('+');
+
+				var types = assembly.MainModule.Types;
+				foreach (var ntype in nested) {
+					if (type == null) {
+						// Use namespace first time.
+						type = types.FirstOrDefault (t => t.FullName == ntype);
+					} else {
+						type = types.FirstOrDefault (t => t.Name == ntype);
+					}
+
+					if (type == null) {
+						logger.LogWarning ("Could not find type: {0}", ntype);
+						return false;
+					}
+
+					types = type.NestedTypes;
 				}
 
-				if (type == null) {
-					logger.LogWarning ("Could not find type: {0}", ntype);
+				var parensStart = sfData.MethodSignature.IndexOf ('(');
+				var methodName = sfData.MethodSignature.Substring (0, parensStart).TrimEnd ();
+				var methodParameters = sfData.MethodSignature.Substring (parensStart);
+				var methods = type.Methods.Where (m => CompareName (m, methodName) && CompareParameters (m.Parameters, methodParameters)).ToArray ();
+				if (methods.Length == 0) {
+					logger.LogWarning ("Could not find method: {0}", methodName);
+					return false;
+				}
+				if (methods.Length > 1) {
+					logger.LogWarning ("Ambiguous match for method: {0}", sfData.MethodSignature);
 					return false;
 				}
+				var method = methods [0];
 
-				types = type.NestedTypes;
-			}
+				int ilOffset;
+				if (sfData.IsILOffset) {
+					ilOffset = sfData.Offset;
+				} else {
+					if (seqPointInfo == null)
+						return false;
 
-			var parensStart = sfData.MethodSignature.IndexOf ('(');
-			var methodName = sfData.MethodSignature.Substring (0, parensStart).TrimEnd ();
-			var methodParameters = sfData.MethodSignature.Substring (parensStart);
-			var methods = type.Methods.Where (m => CompareName (m, methodName) && CompareParameters (m.Parameters, methodParameters)).ToArray ();
-			if (methods.Length == 0) {
-				logger.LogWarning ("Could not find method: {0}", methodName);
-				return false;
-			}
-			if (methods.Length > 1) {
-				logger.LogWarning ("Ambiguous match for method: {0}", sfData.MethodSignature);
-				return false;
-			}
-			var method = methods [0];
+					ilOffset = seqPointInfo.GetILOffset (method.MetadataToken.ToInt32 (), sfData.MethodIndex, sfData.Offset);
+				}
 
-			int ilOffset;
-			if (sfData.IsILOffset) {
-				ilOffset = sfData.Offset;
-			} else {
-				if (seqPointInfo == null)
+				if (ilOffset < 0)
 					return false;
 
-				ilOffset = seqPointInfo.GetILOffset (method.MetadataToken.ToInt32 (), sfData.MethodIndex, sfData.Offset);
-			}
+				if (!method.DebugInformation.HasSequencePoints)
+					return false;
 
-			if (ilOffset < 0)
-				return false;
+				SequencePoint prev = null;
+				foreach (var sp in method.DebugInformation.SequencePoints.OrderBy (l => l.Offset)) {
+					if (sp.Offset >= ilOffset) {
+						sfData.SetLocation (sp.Document.Url, sp.StartLine);
+						return true;
+					}
 
-			if (!method.DebugInformation.HasSequencePoints)
-				return false;
+					prev = sp;
+				}
 
-			SequencePoint prev = null;
-			foreach (var sp in method.DebugInformation.SequencePoints.OrderBy (l => l.Offset)) {
-				if (sp.Offset >= ilOffset) {
-					sfData.SetLocation (sp.Document.Url, sp.StartLine);
+				if (prev != null) {
+					sfData.SetLocation (prev.Document.Url, prev.StartLine);
 					return true;
 				}
 
-				prev = sp;
-			}
-
-			if (prev != null) {
-				sfData.SetLocation (prev.Document.Url, prev.StartLine);
-				return true;
+				return false;
 			}
-
-			return false;
 		}
 
 		static bool CompareName (MethodDefinition candidate, string expected)
diff --git a/mcs/tools/mono-symbolicate/SymbolManager.cs b/mcs/tools/mono-symbolicate/SymbolManager.cs
index a204788306b..eb06043a823 100644
--- a/mcs/tools/mono-symbolicate/SymbolManager.cs
+++ b/mcs/tools/mono-symbolicate/SymbolManager.cs
@@ -107,10 +107,11 @@ namespace Mono
 						continue;
 					}
 
-					var assembly = AssemblyDefinition.ReadAssembly (assemblyPath);
-
-					var mvid = assembly.MainModule.Mvid.ToString ("N");
-					var mvidDir = Path.Combine (msymDir, mvid);
+					string mvidDir;
+					using (var assembly = AssemblyDefinition.ReadAssembly (assemblyPath)) {
+						var mvid = assembly.MainModule.Mvid.ToString ("N");
+						mvidDir = Path.Combine (msymDir, mvid);
+					}
 
 					if (Directory.Exists (mvidDir)) {
 						try {
diff --git a/mcs/tools/security/permview.cs b/mcs/tools/security/permview.cs
index 422de82f621..257a814925b 100644
--- a/mcs/tools/security/permview.cs
+++ b/mcs/tools/security/permview.cs
@@ -375,28 +375,29 @@ namespace Mono.Tools {
 					return 0;
 
 				string assemblyName = args [args.Length - 1];
-				AssemblyDefinition ad = AssemblyDefinition.ReadAssembly (assemblyName);
-				if (ad != null) {
-					bool complete = false;
-					
-					if (declarative) {
-						// full output (assembly+classes+methods)
-						complete = ProcessAssemblyComplete (tw, ad);
-					} else if (xmloutput) {
-						// full output in XML (for easier diffs after c14n)
-						complete = ProcessAssemblyXml (tw, ad);
-					} else {
-						// default (assembly only)
-						complete = ProcessAssemblyOnly (tw, ad);
-					}
+				using (AssemblyDefinition ad = AssemblyDefinition.ReadAssembly (assemblyName)) {
+					if (ad != null) {
+						bool complete = false;
+
+						if (declarative) {
+							// full output (assembly+classes+methods)
+							complete = ProcessAssemblyComplete (tw, ad);
+						} else if (xmloutput) {
+							// full output in XML (for easier diffs after c14n)
+							complete = ProcessAssemblyXml (tw, ad);
+						} else {
+							// default (assembly only)
+							complete = ProcessAssemblyOnly (tw, ad);
+						}
 
-					if (!complete) {
-						Console.Error.WriteLine ("Couldn't reflect informations.");
-						return 1;
+						if (!complete) {
+							Console.Error.WriteLine ("Couldn't reflect informations.");
+							return 1;
+						}
+					} else {
+						Console.Error.WriteLine ("Couldn't load assembly '{0}'.", assemblyName);
+						return 2;
 					}
-				} else {
-					Console.Error.WriteLine ("Couldn't load assembly '{0}'.", assemblyName);
-					return 2;
 				}
 				tw.Close ();
 			}