Thread-safety for LoadedAssembly.GetTypeSystemOrNull()

ILSpy/LoadedAssembly.cs

@@ -146,7 +146,7 @@ namespace ICSharpCode.ILSpy
 		ICompilation typeSystem;
 
 		/// <summary>
-		/// Gets a type system containing all types from this assembly + primitve types from mscorlib.
+		/// Gets a type system containing all types from this assembly + primitive types from mscorlib.
 		/// Returns null in case of load errors.
 		/// </summary>
 		/// <remarks>
@@ -154,20 +154,23 @@ namespace ICSharpCode.ILSpy
 		/// </remarks>
 		public ICompilation GetTypeSystemOrNull()
 		{
-			if (typeSystem != null)
+			return LazyInitializer.EnsureInitialized(ref this.typeSystem, () => {
-				return typeSystem;
 				var module = GetPEFileOrNull();
 				if (module == null)
 					return null;
-			return typeSystem = new SimpleCompilation(
+				return new SimpleCompilation(
 					module.WithOptions(TypeSystemOptions.Default | TypeSystemOptions.Uncached | TypeSystemOptions.KeepModifiers),
 					MinimalCorlib.Instance);
+			});
 		}
 
+		readonly object typeSystemWithOptionsLockObj = new object();
 		ICompilation typeSystemWithOptions;
 		TypeSystemOptions currentTypeSystemOptions;
 
 		public ICompilation GetTypeSystemOrNull(TypeSystemOptions options)
+		{
+			lock (typeSystemWithOptionsLockObj)
 			{
 				if (typeSystemWithOptions != null && options == currentTypeSystemOptions)
 					return typeSystemWithOptions;
@@ -179,6 +182,7 @@ namespace ICSharpCode.ILSpy
 					module.WithOptions(options | TypeSystemOptions.Uncached | TypeSystemOptions.KeepModifiers),
 					MinimalCorlib.Instance);
 			}
+		}
 
 		public AssemblyList AssemblyList => assemblyList;