[mcs] C# 7.2 non-trailing named arguments

8 files changed, 49 insertions, 11 deletions

diff --git a/mcs/errors/cs1738-2.cs b/mcs/errors/cs1738-2.cs
index f59221f4c7a..44b3f6d1b14 100644
--- a/mcs/errors/cs1738-2.cs
+++ b/mcs/errors/cs1738-2.cs
@@ -1,4 +1,4 @@
-// CS1738: Named arguments must appear after the positional arguments
+// CS1738: Named arguments must appear after the positional arguments when using language version older than 7.2
 // Line: 13
 
 using System;
diff --git a/mcs/errors/cs1738-3.cs b/mcs/errors/cs1738-3.cs
index 53c4efc3553..901ac0e5d59 100644
--- a/mcs/errors/cs1738-3.cs
+++ b/mcs/errors/cs1738-3.cs
@@ -1,4 +1,4 @@
-// CS1738: Named arguments must appear after the positional arguments
+// CS1738: Named arguments must appear after the positional arguments when using language version older than 7.2
 // Line: 14
 
 class C
diff --git a/mcs/errors/cs1738.cs b/mcs/errors/cs1738.cs
index dab9a61160b..537bc17b917 100644
--- a/mcs/errors/cs1738.cs
+++ b/mcs/errors/cs1738.cs
@@ -1,4 +1,4 @@
-// CS1738: Named arguments must appear after the positional arguments
+// CS1738: Named arguments must appear after the positional arguments when using language version older than 7.2
 // Line: 12
 
 class C
diff --git a/mcs/mcs/cs-parser.jay b/mcs/mcs/cs-parser.jay
index e33d869d563..e2118a23f0f 100644
--- a/mcs/mcs/cs-parser.jay
+++ b/mcs/mcs/cs-parser.jay
@@ -865,7 +865,7 @@ attribute_arguments
 		}
 		
 		Arguments args = ((Arguments) o [0]);
-		if (args.Count > 0 && !($3 is NamedArgument) && args [args.Count - 1] is NamedArgument)
+		if (lang_version < LanguageVersion.V_7_2 && args.Count > 0 && !($3 is NamedArgument) && args [args.Count - 1] is NamedArgument)
 			Error_NamedArgumentExpected ((NamedArgument) args [args.Count - 1]);
 		
 		args.Add ((Argument) $3);
@@ -3856,7 +3856,7 @@ argument_list
 	| argument_list COMMA argument
 	  {
 		Arguments list = (Arguments) $1;
-		if (list [list.Count - 1] is NamedArgument)
+		if (lang_version < LanguageVersion.V_7_2 && list [list.Count - 1] is NamedArgument)
 			Error_NamedArgumentExpected ((NamedArgument) list [list.Count - 1]);
 		
 		list.Add ((Argument) $3);
@@ -4001,7 +4001,7 @@ expression_list_arguments
 	| expression_list_arguments COMMA expression_list_argument
 	  {
 		Arguments args = (Arguments) $1;
-		if (args [args.Count - 1] is NamedArgument && !($3 is NamedArgument))
+		if (lang_version < LanguageVersion.V_7_2 && args [args.Count - 1] is NamedArgument && !($3 is NamedArgument))
 			Error_NamedArgumentExpected ((NamedArgument) args [args.Count - 1]);
 	  
 		args.Add ((Argument) $3);
@@ -4792,7 +4792,7 @@ pattern_list
 	| pattern_list COMMA pattern_argument
 	  {
 		Arguments args = (Arguments) $1;
-		if (args [args.Count - 1] is NamedArgument && !($3 is NamedArgument))
+		if (lang_version < LanguageVersion.V_7_2 && args [args.Count - 1] is NamedArgument && !($3 is NamedArgument))
 			Error_NamedArgumentExpected ((NamedArgument) args [args.Count - 1]);
 
 		args.Add ((Argument) $3);
@@ -7795,7 +7795,7 @@ void Warning_EmptyStatement (Location loc)
 
 void Error_NamedArgumentExpected (NamedArgument a)
 {
-	report.Error (1738, a.Location, "Named arguments must appear after the positional arguments");
+	report.Error (1738, a.Location, "Named arguments must appear after the positional arguments when using language version older than 7.2");
 }
 
 void Error_MissingInitializer (Location loc)
diff --git a/mcs/mcs/dynamic.cs b/mcs/mcs/dynamic.cs
index 32f361ba96a..f8314b2f3cd 100644
--- a/mcs/mcs/dynamic.cs
+++ b/mcs/mcs/dynamic.cs
@@ -279,6 +279,7 @@ namespace Mono.CSharp
 
 		protected bool DoResolveCore (ResolveContext rc)
 		{
+			int i = 0;
 			foreach (var arg in arguments) {
 				if (arg.Type == InternalType.VarOutType) {
 					// Should be special error message about dynamic dispatch
@@ -286,6 +287,11 @@ namespace Mono.CSharp
 				} else if (arg.Type == InternalType.DefaultType) {
 					rc.Report.Error (8311, arg.Expr.Location, "Cannot use a default literal as an argument to a dynamically dispatched operation");
 				}
+
+				// Forced limitation because Microsoft.CSharp needs to catch up
+				if (i > 0 && arguments [i - 1] is NamedArgument && !(arguments [i] is NamedArgument))
+					rc.Report.Error (8324, loc, "Named argument specifications must appear after all fixed arguments have been specified in a dynamic invocation");
+				++i;
 			}
 
 			if (rc.CurrentTypeParameters != null && rc.CurrentTypeParameters[0].IsMethodTypeParameter)
diff --git a/mcs/mcs/ecore.cs b/mcs/mcs/ecore.cs
index 4f7c6144cfa..9b40d8a2399 100644
--- a/mcs/mcs/ecore.cs
+++ b/mcs/mcs/ecore.cs
@@ -6084,9 +6084,15 @@ namespace Mono.CSharp {
 						else
 							ec.Report.SymbolRelatedToPreviousError (member);
 
-						ec.Report.Error (1744, na.Location,
-							"Named argument `{0}' cannot be used for a parameter which has positional argument specified",
-							na.Name);
+						if (name_index > a_idx) {
+							ec.Report.Error (8323, na.Location,
+								"Named argument `{0}' is used out of position but is followed by positional argument",
+								na.Name);
+						} else {
+							ec.Report.Error (1744, na.Location,
+								"Named argument `{0}' cannot be used for a parameter which has positional argument specified",
+								na.Name);
+						}
 					}
 				}
 				
diff --git a/mcs/tests/test-named-11.cs b/mcs/tests/test-named-11.cs
new file mode 100644
index 00000000000..a01d2883b9c
--- /dev/null
+++ b/mcs/tests/test-named-11.cs
@@ -0,0 +1,13 @@
+// Compiler options: -langversion:7.2
+
+class X
+{
+	public static void Main ()
+	{
+		Test (arg: 1, "");
+	}
+
+	static void Test (int arg, string str)
+	{
+	}
+}
\ 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 8f37458a29d..78e6782767e 100644
--- a/mcs/tests/ver-il-net_4_x.xml
+++ b/mcs/tests/ver-il-net_4_x.xml
@@ -70869,6 +70869,19 @@
       </method>
     </type>
   </test>
+  <test name="test-named-11.cs">
+    <type name="X">
+      <method name="Void Main()" attrs="150">
+        <size>13</size>
+      </method>
+      <method name="Void Test(Int32, System.String)" attrs="145">
+        <size>2</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-nameof-01.cs">
     <type name="X">
       <method name="Int32 Main()" attrs="150">