From c6bd624372257b2c271d16bbafe9783156dfef86 Mon Sep 17 00:00:00 2001
From: Marek Safar <marek.safar@gmail.com>
Date: Tue, 21 Jan 2014 16:31:50 +0100
Subject: [PATCH] [mcs] Check for initially unassigned struct instance
 variables of unassigned structs.

---
 mcs/errors/cs0165-44.cs         | 21 ++++++++++++++++++
 mcs/errors/known-issues-net_4_5 |  5 -----
 mcs/mcs/ecore.cs                | 39 +++++++++++++++++++++------------
 mcs/tests/test-829.cs           | 12 ++++++++++
 mcs/tests/ver-il-net_4_5.xml    |  3 +++
 5 files changed, 61 insertions(+), 19 deletions(-)
 create mode 100644 mcs/errors/cs0165-44.cs

diff --git a/mcs/errors/cs0165-44.cs b/mcs/errors/cs0165-44.cs
new file mode 100644
index 00000000000..d4b6988c467
--- /dev/null
+++ b/mcs/errors/cs0165-44.cs
@@ -0,0 +1,21 @@
+// CS0165: Use of unassigned local variable `x'
+// Line: 19
+
+struct S
+{
+	public object O;
+}
+
+class X
+{
+	public S s;
+}
+
+class C
+{
+	public static void Main ()
+	{
+		X x;
+		x.s.O = 2;
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/known-issues-net_4_5 b/mcs/errors/known-issues-net_4_5
index a59413c220f..1e07f7c667e 100644
--- a/mcs/errors/known-issues-net_4_5
+++ b/mcs/errors/known-issues-net_4_5
@@ -17,8 +17,3 @@ cs0080.cs
 # Operators
 cs0457-2.cs
 cs0457.cs
-
-cs1060.cs NO ERROR
-cs1060-2.cs NO ERROR
-cs1060-3.cs NO ERROR
-cs1060-4.cs
diff --git a/mcs/mcs/ecore.cs b/mcs/mcs/ecore.cs
index 36b2ee930d1..3bad645c309 100644
--- a/mcs/mcs/ecore.cs
+++ b/mcs/mcs/ecore.cs
@@ -5814,25 +5814,36 @@ namespace Mono.CSharp {
 			}
 
 			var fe = InstanceExpression as FieldExpr;
-			if (fe != null || lvalue_instance) {
-				if (fe == null)
-					return;
+			if (fe != null) {
+				Expression instance;
 
-				/*
-				while (fe.InstanceExpression is FieldExpr) {
-					fe = (FieldExpr) fe.InstanceExpression;
-					if (!fe.Spec.DeclaringType.IsStruct)
-						continue;
+				do {
+					instance = fe.InstanceExpression;
+					var fe_instance = instance as FieldExpr;
+					if ((fe_instance != null && !fe_instance.IsStatic) || instance is LocalVariableReference) {
+						if (TypeSpec.IsReferenceType (fe.Type) && instance.Type.IsStruct) {
+							var var = InstanceExpression as IVariableReference;
+							if (var != null && var.VariableInfo == null) {
+								var var_inst = instance as IVariableReference;
+								if (var_inst == null || (var_inst.VariableInfo != null && !fc.IsDefinitelyAssigned (var_inst.VariableInfo)))
+									fc.Report.Warning (1060, 1, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
+							}
+						}
 
-					if (fe.VariableInfo != null && fc.IsStructFieldDefinitelyAssigned (fe.VariableInfo, fe.Name)) {
-						fc.Report.Warning (1060, 1, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
+						if (fe_instance != null) {
+							fe = fe_instance;
+							continue;
+						}
 					}
-				}
 
-				fe.InstanceExpression.FlowAnalysis (fc);
-				*/
+					break;
+				} while (true);
+
+				if (instance != null && TypeSpec.IsReferenceType (instance.Type))
+					instance.FlowAnalysis (fc);
 			} else {
-				InstanceExpression.FlowAnalysis (fc);
+				if (TypeSpec.IsReferenceType (InstanceExpression.Type))
+					InstanceExpression.FlowAnalysis (fc);
 			}
 		}
 
diff --git a/mcs/tests/test-829.cs b/mcs/tests/test-829.cs
index 6a7e2c8a9c5..d5c83a033f9 100644
--- a/mcs/tests/test-829.cs
+++ b/mcs/tests/test-829.cs
@@ -23,6 +23,18 @@ class C
 			s.F = 1.0f;
 		}
 	}
+
+	static void Test2 (bool b)
+	{
+		S s;
+		if (b) {
+			s.s2 = new S2 ();
+			s.F = 1.0f;
+		} else {
+			s.s2.f1 = 2.1f;
+			s.F = 1.0f;
+		}
+	}
 	
 	public static int Main ()
 	{
diff --git a/mcs/tests/ver-il-net_4_5.xml b/mcs/tests/ver-il-net_4_5.xml
index c76dd77f542..3e2ae6cfb51 100644
--- a/mcs/tests/ver-il-net_4_5.xml
+++ b/mcs/tests/ver-il-net_4_5.xml
@@ -47563,6 +47563,9 @@
       <method name="Void .ctor()" attrs="6278">
         <size>7</size>
       </method>
+      <method name="Void Test2(Boolean)" attrs="145">
+        <size>74</size>
+      </method>
     </type>
   </test>
   <test name="test-83.cs">
-- 
2.25.1