Merge pull request #45999 from diryboy/qqe

Classify ??= as an operator.

Author: 333fred

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

@@ -145,7 +145,7 @@ public static IEnumerable<SyntaxKind> GetPreprocessorKeywordKinds()
 
         public static bool IsPunctuation(SyntaxKind kind)
         {
-            return kind >= SyntaxKind.TildeToken && kind <= SyntaxKind.PercentEqualsToken;
+            return kind >= SyntaxKind.TildeToken && kind <= SyntaxKind.QuestionQuestionEqualsToken;
         }
 
         public static bool IsLanguagePunctuation(SyntaxKind kind)

src/EditorFeatures/CSharpTest/Classification/SyntacticClassifierTests.cs

@@ -3141,6 +3141,7 @@ public void method()
         i ^= i;
         i <<= i;
         i >>= i;
+        i ??= i;
         object s = x => x + 1;
         Point point;
         unsafe
@@ -3374,6 +3375,10 @@ public void method()
                 Operators.GreaterThanGreaterThanEquals,
                 Identifier("i"),
                 Punctuation.Semicolon,
+                Identifier("i"),
+                Operators.QuestionQuestionEquals,
+                Identifier("i"),
+                Punctuation.Semicolon,
                 Keyword("object"),
                 Local("s"),
                 Operators.Equals,

src/EditorFeatures/TestUtilities/Classification/FormattedClassifications.Operators.cs

@@ -53,6 +53,7 @@ private static FormattedClassification New(string text)
             public static FormattedClassification PlusEquals { get; } = New("+=");
             public static FormattedClassification PlusPlus { get; } = New("++");
             public static FormattedClassification QuestionMark { get; } = New("?");
+            public static FormattedClassification QuestionQuestionEquals { get; } = New("??=");
             public static FormattedClassification Slash { get; } = New("/");
             public static FormattedClassification SlashEquals { get; } = New("/=");
             public static FormattedClassification Tilde { get; } = New("~");

src/Workspaces/CSharp/Portable/Classification/ClassificationHelpers.cs

@@ -440,6 +440,7 @@ private static bool IsOperator(this SyntaxKind kind)
                 case SyntaxKind.MinusEqualsToken:
                 case SyntaxKind.CaretEqualsToken:
                 case SyntaxKind.PercentEqualsToken:
+                case SyntaxKind.QuestionQuestionEqualsToken:
                     return true;
 
                 default: