From 25497f5308b801d72fd1e1ed090bf08c42456fb5 Mon Sep 17 00:00:00 2001
From: Marek Safar <marek.safar@gmail.com>
Date: Fri, 18 Dec 2015 21:12:34 +0100
Subject: [PATCH] [mcs] Propagate null operator flag during standalone to
 extension methods promotion. Fixes #37080

---
 mcs/mcs/ecore.cs                   |  1 +
 mcs/tests/test-null-operator-22.cs | 33 ++++++++++++++++++++++++++++++
 mcs/tests/ver-il-net_4_x.xml       | 29 ++++++++++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 mcs/tests/test-null-operator-22.cs

diff --git a/mcs/mcs/ecore.cs b/mcs/mcs/ecore.cs
index 08bce8a9d70..b74da01e65c 100644
--- a/mcs/mcs/ecore.cs
+++ b/mcs/mcs/ecore.cs
@@ -4255,6 +4255,7 @@ namespace Mono.CSharp {
 
 			var emg = new ExtensionMethodGroupExpr (methods, InstanceExpression, loc);
 			emg.SetTypeArguments (rc, type_arguments);
+			emg.ConditionalAccess = ConditionalAccess;
 			return emg;
 		}
 
diff --git a/mcs/tests/test-null-operator-22.cs b/mcs/tests/test-null-operator-22.cs
new file mode 100644
index 00000000000..04115f9385e
--- /dev/null
+++ b/mcs/tests/test-null-operator-22.cs
@@ -0,0 +1,33 @@
+class A
+{
+	public A this [string arg] {
+		get {
+			return new A ();
+		}
+		set {
+		}
+	}
+
+	public int Count (string a)
+	{
+		return 1;
+	}
+}
+
+static class B
+{
+	public static string Count (this A arg)
+	{
+		return "x";
+	}
+}
+
+class X
+{
+	public static void Main ()
+	{
+		var a = new A ();
+		var b = a ["b"]?.Count ();
+		System.Console.WriteLine (b);
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/ver-il-net_4_x.xml b/mcs/tests/ver-il-net_4_x.xml
index d543f197bd7..b2352089203 100644
--- a/mcs/tests/ver-il-net_4_x.xml
+++ b/mcs/tests/ver-il-net_4_x.xml
@@ -69665,6 +69665,35 @@
       </method>
     </type>
   </test>
+  <test name="test-null-operator-22.cs">
+    <type name="A">
+      <method name="A get_Item(System.String)" attrs="2182">
+        <size>14</size>
+      </method>
+      <method name="Void set_Item(System.String, A)" attrs="2182">
+        <size>2</size>
+      </method>
+      <method name="Int32 Count(System.String)" attrs="134">
+        <size>10</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+    <type name="B">
+      <method name="System.String Count(A)" attrs="150">
+        <size>14</size>
+      </method>
+    </type>
+    <type name="X">
+      <method name="Void Main()" attrs="150">
+        <size>41</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-partial-01.cs">
     <type name="Foo.Hello">
       <method name="Void .ctor()" attrs="6278">
-- 
2.25.1