Merge pull request #3256 from NextTurn/sa1119

Update SA1119 for stackalloc expressions

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp8/MaintainabilityRules/SA1119CSharp8UnitTests.cs

@@ -148,6 +148,24 @@ public unsafe string TestMethod(int n, byte* a, byte* b)
         return (n switch { 1 => a, 2 => b })->ToString();
     }
 }
+";
+
+            await VerifyCSharpDiagnosticAsync(LanguageVersion.CSharp8, testCode, DiagnosticResult.EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);
+        }
+
+        [Fact]
+        public async Task TestStackAllocExpressionInExpressionAsync()
+        {
+            const string testCode = @"public class TestClass
+{
+    public unsafe void TestMethod()
+    {
+        var ptr1 = stackalloc byte[1];
+        var span1 = (stackalloc byte[1]);
+        var ptr2 = stackalloc[] { 0 };
+        var span2 = (stackalloc[] { 0 });
+    }
+}
 ";
 
             await VerifyCSharpDiagnosticAsync(LanguageVersion.CSharp8, testCode, DiagnosticResult.EmptyDiagnosticResults, CancellationToken.None).ConfigureAwait(false);

StyleCop.Analyzers/StyleCop.Analyzers/MaintainabilityRules/SA1119StatementMustNotUseUnnecessaryParenthesis.cs

@@ -137,6 +137,13 @@ private static void HandleParenthesizedExpression(SyntaxNodeAnalysisContext cont
                         return;
                     }
 
+                    if ((node.Expression.IsKind(SyntaxKind.StackAllocArrayCreationExpression)
+                        || node.Expression.IsKind(SyntaxKindEx.ImplicitStackAllocArrayCreationExpression))
+                        && node.Parent.IsKind(SyntaxKind.EqualsValueClause))
+                    {
+                        return;
+                    }
+
                     ReportDiagnostic(context, node);
                 }
                 else