Update per code review comments.

docs/features/patterns.md

@@ -82,7 +82,7 @@ property_subpattern
     ;
 ```
 
-> Note: There is technically an ambiguity between *type* in an `is-expression` and *constant_pattern*, either of which might be a valid parse of a qualified identifier. For compatibility we try to bind it as a type for compatibility with previous versions of the language; only if that fails do we resolve it as we do in other contexts, to the first thing found (which must be either a constant or a type).
+> Note: There is technically an ambiguity between *type* in an `is-expression` and *constant_pattern*, either of which might be a valid parse of a qualified identifier. We try to bind it as a type for compatibility with previous versions of the language; only if that fails do we resolve it as we do in other contexts, to the first thing found (which must be either a constant or a type). This ambiguity is only present on the right-hand-side of an `is` expression.
 
 ### Type Pattern
 

src/Compilers/CSharp/Portable/CSharpResources.Designer.cs

@@ -6866,7 +6866,7 @@ internal class CSharpResources {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to No &apos;operator is&apos; declaration in &apos;{0}&apos; was found with {1} out parameters.
+        ///   Looks up a localized string similar to No &apos;operator is&apos; declaration in &apos;{0}&apos; was found with {1} out parameter(s).
         /// </summary>
         internal static string ERR_OperatorIsParameterCount {
             get {

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -4861,7 +4861,7 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
     <value>Ambiguous 'operator is' declarations found in type '{0}'.</value>
   </data>
   <data name="ERR_OperatorIsParameterCount" xml:space="preserve">
-    <value>No 'operator is' declaration in '{0}' was found with {1} out parameters</value>
+    <value>No 'operator is' declaration in '{0}' was found with {1} out parameter(s)</value>
   </data>
   <data name="ERR_OperatorIsRequiresOut" xml:space="preserve">
     <value>All but the first parameter of user-defined 'operator is' require the 'out' modifier.</value>

src/Compilers/CSharp/Portable/Syntax/LambdaUtilities.cs

@@ -353,7 +353,8 @@ internal static bool IsQueryPairLambda(SyntaxNode syntax)
         }
 
         /// <summary>
-        /// Returns true if the specified node is a kind could represent a closure scope -- that is a scope of a captured variable.
+        /// Returns true if the specified node is of a kind that could represent a closure scope -- that
+        /// is, a scope of a captured variable.
         /// Doesn't check whether or not the node actually declares any captured variable.
         /// </summary>
         internal static bool IsClosureScope(SyntaxNode node)

src/Compilers/CSharp/Test/Semantic/Diagnostics/OperationAnalyzerTests.cs

@@ -178,10 +178,10 @@ public void M1(object o)
 ";
             CreateCompilationWithMscorlib45(source, options: TestOptions.DebugExe, parseOptions: patternParseOptions)
             .VerifyDiagnostics(
-                // (13,18): error CS8157: No 'operator is' declaration in 'ArrayList' was found with 1 out parameters
+                // (13,18): error CS8157: No 'operator is' declaration in 'ArrayList' was found with 1 out parameter(s)
                 //             case System.Collections.ArrayList(2):
                 Diagnostic(ErrorCode.ERR_OperatorIsParameterCount, "System.Collections.ArrayList(2)").WithArguments("System.Collections.ArrayList", "1").WithLocation(13, 18),
-                // (20,18): error CS8157: No 'operator is' declaration in 'ArrayList' was found with 1 out parameters
+                // (20,18): error CS8157: No 'operator is' declaration in 'ArrayList' was found with 1 out parameter(s)
                 //             case System.Collections.ArrayList(2): x
                 Diagnostic(ErrorCode.ERR_OperatorIsParameterCount, "System.Collections.ArrayList(2)").WithArguments("System.Collections.ArrayList", "1").WithLocation(20, 18)
                 )

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTests.cs

@@ -101,7 +101,7 @@ public static void Main()
                 // (12,17): error CS0103: The name 'i4' does not exist in the current context
                 //         let var i4 = 3; // let
                 Diagnostic(ErrorCode.ERR_NameNotInContext, "i4").WithArguments("i4").WithLocation(12, 17),
-                // (15,18): error CS8157: No 'operator is' declaration in 'Vec' was found with 1 out parameters
+                // (15,18): error CS8157: No 'operator is' declaration in 'Vec' was found with 1 out parameter(s)
                 //         if (q is Vec(3)) {} // recursive pattern
                 Diagnostic(ErrorCode.ERR_OperatorIsParameterCount, "Vec(3)").WithArguments("Vec", "1").WithLocation(15, 18),
                 // (12,13): warning CS0168: The variable 'var' is declared but never used
@@ -134,7 +134,7 @@ public static void Main()
                 // (12,17): error CS0103: The name 'i4' does not exist in the current context
                 //         let var i4 = 3; // let
                 Diagnostic(ErrorCode.ERR_NameNotInContext, "i4").WithArguments("i4").WithLocation(12, 17),
-                // (15,18): error CS8157: No 'operator is' declaration in 'Vec' was found with 1 out parameters
+                // (15,18): error CS8157: No 'operator is' declaration in 'Vec' was found with 1 out parameter(s)
                 //         if (q is Vec(3)) {} // recursive pattern
                 Diagnostic(ErrorCode.ERR_OperatorIsParameterCount, "Vec(3)").WithArguments("Vec", "1").WithLocation(15, 18),
                 // (8,13): warning CS0219: The variable 'i2' is assigned but its value is never used
@@ -152,7 +152,7 @@ public static void Main()
             var experimentalParseOptions = regularParseOptions
                 .WithPreprocessorSymbols(new[] { "__DEMO_EXPERIMENTAL__" });
             CreateCompilationWithMscorlib45(source, options: TestOptions.DebugExe, parseOptions: experimentalParseOptions).VerifyDiagnostics(
-                // (15,18): error CS8157: No 'operator is' declaration in 'Vec' was found with 1 out parameters
+                // (15,18): error CS8157: No 'operator is' declaration in 'Vec' was found with 1 out parameter(s)
                 //         if (q is Vec(3)) {} // recursive pattern
                 Diagnostic(ErrorCode.ERR_OperatorIsParameterCount, "Vec(3)").WithArguments("Vec", "1").WithLocation(15, 18),
                 // (8,13): warning CS0219: The variable 'i2' is assigned but its value is never used