Fix issue #70183: adjust the plural for expression collection

src/Compilers/CSharp/Portable/BoundTree/Formatting.cs

@@ -170,7 +170,7 @@ public override object Display
     internal partial class BoundUnconvertedCollectionExpression
     {
         public override object Display
-            => (Type is null) ? MessageID.IDS_FeatureCollectionExpressions.Localize() : base.Display;
+            => (Type is null) ? MessageID.IDS_CollectionExpression.Localize() : base.Display;
     }
 
     internal partial class BoundPassByCopy

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -6850,6 +6850,9 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="IDS_FeatureCollectionExpressions" xml:space="preserve">
     <value>collection expressions</value>
   </data>
+  <data name="IDS_CollectionExpression" xml:space="preserve">
+    <value>collection expression</value>
+  </data>
   <data name="ERR_CollectionExpressionTargetTypeNotConstructible" xml:space="preserve">
     <value>Cannot initialize type '{0}' with a collection expression because the type is not constructible.</value>
   </data>

src/Compilers/CSharp/Portable/Errors/MessageID.cs

@@ -302,6 +302,7 @@ internal enum MessageID
         IDS_FeatureExtensions = MessageBase + 12853,
         IDS_FeatureNullConditionalAssignment = MessageBase + 12854,
         IDS_FeatureExpressionOptionalAndNamedArguments = MessageBase + 12855,
+        IDS_CollectionExpression = MessageBase + 12856,
     }
 
     // Message IDs may refer to strings that need to be localized.

src/Compilers/CSharp/Test/Emit3/Semantics/CollectionExpressionTests.cs

@@ -3311,9 +3311,9 @@ static void Main(string[] args)
                 """;
             var comp = CreateCompilation(source);
             comp.VerifyEmitDiagnostics(
-                // (6,17): error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'collection expressions' and 'collection expressions'
+                // (6,17): error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'collection expression' and 'collection expression'
                 //         var y = b ? [new int[0]] : [[1, 2, 3]];
-                Diagnostic(ErrorCode.ERR_InvalidQM, "b ? [new int[0]] : [[1, 2, 3]]").WithArguments("collection expressions", "collection expressions").WithLocation(6, 17));
+                Diagnostic(ErrorCode.ERR_InvalidQM, "b ? [new int[0]] : [[1, 2, 3]]").WithArguments("collection expression", "collection expression").WithLocation(6, 17));
         }
 
         [Fact]
@@ -3436,9 +3436,9 @@ static void Main()
                 """;
             var comp = CreateCompilation(new[] { source, s_collectionExtensions });
             comp.VerifyEmitDiagnostics(
-                // 0.cs(9,29): error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'collection expressions' and 'collection expressions'
+                // 0.cs(9,29): error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'collection expression' and 'collection expression'
                 //         var a = AsArray([.. b ? [x] : [y]]);
-                Diagnostic(ErrorCode.ERR_InvalidQM, "b ? [x] : [y]").WithArguments("collection expressions", "collection expressions").WithLocation(9, 29));
+                Diagnostic(ErrorCode.ERR_InvalidQM, "b ? [x] : [y]").WithArguments("collection expression", "collection expression").WithLocation(9, 29));
         }
 
         [Fact]
@@ -9763,9 +9763,9 @@ static string[] Append(string a, string b, bool c)
                 """;
             var comp = CreateCompilation(source);
             comp.VerifyEmitDiagnostics(
-                // (5,26): error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'collection expressions' and 'collection expressions'
+                // (5,26): error CS0173: Type of conditional expression cannot be determined because there is no implicit conversion between 'collection expression' and 'collection expression'
                 //         return [a, b, .. c ? [null] : []];
-                Diagnostic(ErrorCode.ERR_InvalidQM, "c ? [null] : []").WithArguments("collection expressions", "collection expressions").WithLocation(5, 26));
+                Diagnostic(ErrorCode.ERR_InvalidQM, "c ? [null] : []").WithArguments("collection expression", "collection expression").WithLocation(5, 26));
         }
 
         [Fact]
@@ -28022,9 +28022,9 @@ static void Main(List<int> list)
                 }
                 """;
             CreateCompilation(source).VerifyEmitDiagnostics(
-                // (7,9): error CS0019: Operator '+' cannot be applied to operands of type 'collection expressions' and 'List<int>'
+                // (7,9): error CS0019: Operator '+' cannot be applied to operands of type 'collection expression' and 'List<int>'
                 //         [] + list;
-                Diagnostic(ErrorCode.ERR_BadBinaryOps, "[] + list").WithArguments("+", "collection expressions", "System.Collections.Generic.List<int>").WithLocation(7, 9),
+                Diagnostic(ErrorCode.ERR_BadBinaryOps, "[] + list").WithArguments("+", "collection expression", "System.Collections.Generic.List<int>").WithLocation(7, 9),
                 // (7,9): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
                 //         [] + list;
                 Diagnostic(ErrorCode.ERR_IllegalStatement, "[] + list").WithLocation(7, 9));