Fix AvoidUninstantiatedInternalClassesRule when no ctor are present

* AvoidUninstantiatedInternalClassesRule.cs: Return false (no NRE)
when no .ctor are found (e.g. struct)
* Test/AvoidUninstantiatedInternalClassesTest.cs: Test case for above

Found/patch by Antoine Vandecreme  <avandecreme@sopragroup.com>

2 files changed, 40 insertions, 0 deletions

diff --git a/gendarme/rules/Gendarme.Rules.Performance/AvoidUninstantiatedInternalClassesRule.cs b/gendarme/rules/Gendarme.Rules.Performance/AvoidUninstantiatedInternalClassesRule.cs
index 94e63e41..518a4519 100644
--- a/gendarme/rules/Gendarme.Rules.Performance/AvoidUninstantiatedInternalClassesRule.cs
+++ b/gendarme/rules/Gendarme.Rules.Performance/AvoidUninstantiatedInternalClassesRule.cs
@@ -200,6 +200,10 @@ namespace Gendarme.Rules.Performance {
 					return false; // more than one ctor
 				constructor = method;
 			}
+
+			if (constructor == null)
+				return false;
+
 			return (constructor.IsPrivate && !constructor.HasParameters);
 		}
 
diff --git a/gendarme/rules/Gendarme.Rules.Performance/Test/AvoidUninstantiatedInternalClassesTest.cs b/gendarme/rules/Gendarme.Rules.Performance/Test/AvoidUninstantiatedInternalClassesTest.cs
index 27105cbb..dae35a2a 100644
--- a/gendarme/rules/Gendarme.Rules.Performance/Test/AvoidUninstantiatedInternalClassesTest.cs
+++ b/gendarme/rules/Gendarme.Rules.Performance/Test/AvoidUninstantiatedInternalClassesTest.cs
@@ -90,6 +90,30 @@ namespace Test.Rules.Performance {
 		}
 	}
 
+	internal struct InternalUninstantiatedStruct {
+
+		public void display ()
+		{
+		}
+
+		public static void Main (string [] args)
+		{
+		}
+	}
+
+	internal struct InternalInstantiatedStruct {
+
+		public void display ()
+		{
+		}
+
+		public static void Main (string [] args)
+		{
+			InternalInstantiatedStruct i = new InternalInstantiatedStruct ();
+			i.display ();
+		}
+	}
+
 	// people may use the following two patterns to have
 	// static classes in C# 1.
 	internal sealed class InternalSealedClassWithPrivateCtor {
@@ -300,6 +324,18 @@ namespace Test.Rules.Performance {
 		}
 
 		[Test]
+		public void InternalInstantiatedStructTest ()
+		{
+			AssertRuleSuccess<InternalInstantiatedStruct> ();
+		}
+
+		[Test]
+		public void InternalUninstantiatedStructTest ()
+		{
+			AssertRuleFailure<InternalUninstantiatedStruct> ();
+		}
+
+		[Test]
 		public void InternalSealedClassWithPrivateCtor ()
 		{
 			AssertRuleDoesNotApply<InternalSealedClassWithPrivateCtor> ();