From 938d1f6ae8d81097c1b62280bcaa42f3c59d05c0 Mon Sep 17 00:00:00 2001
From: David Wengier <david.wengier@microsoft.com>
Date: Sat, 1 Aug 2020 08:35:11 +1000
Subject: [PATCH] Don't offer Use Explicit Type for target typed new (#46469)

---
 .../UseImplicitTypeTests.cs                      | 16 ++++++++++++++++
 .../TypeStyle/CSharpUseImplicitTypeHelper.cs     | 10 ++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/Analyzers/CSharp/Tests/UseImplicitOrExplicitType/UseImplicitTypeTests.cs b/src/Analyzers/CSharp/Tests/UseImplicitOrExplicitType/UseImplicitTypeTests.cs
index 3fb01362b06..fc66247d3b8 100644
--- a/src/Analyzers/CSharp/Tests/UseImplicitOrExplicitType/UseImplicitTypeTests.cs
+++ b/src/Analyzers/CSharp/Tests/UseImplicitOrExplicitType/UseImplicitTypeTests.cs
@@ -2793,5 +2793,21 @@ private void M(object sender, EventArgs e)
     private readonly Action<object, EventArgs> f2;
 }", parameters: new TestParameters(options: ImplicitTypeEverywhere()));
         }
+
+        [WpfFact, Trait(Traits.Feature, Traits.Features.CodeActionsUseImplicitType)]
+        public async Task DoNotSuggestVarForTargetTypedNew()
+        {
+            await TestMissingInRegularAndScriptAsync(
+@"using System;
+
+class Program
+{
+    void Method()
+    {
+        [|string|] p = new('c', 1);
+    }
+
+}", new TestParameters(options: ImplicitTypeEverywhere()));
+        }
     }
 }
diff --git a/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Utilities/TypeStyle/CSharpUseImplicitTypeHelper.cs b/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Utilities/TypeStyle/CSharpUseImplicitTypeHelper.cs
index 0642c63d59c..e67bf339841 100644
--- a/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Utilities/TypeStyle/CSharpUseImplicitTypeHelper.cs
+++ b/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Utilities/TypeStyle/CSharpUseImplicitTypeHelper.cs
@@ -286,6 +286,16 @@ private static bool IsSafeToSwitchToVarWithoutNeedingSpeculation(DeclarationExpr
                 return false;
             }
 
+            // var cannot be used with target typed new
+#if CODE_STYLE
+            if (expression.IsKind(Formatting.SyntaxKindEx.ImplicitObjectCreationExpression))
+#else
+            if (expression.IsKind(SyntaxKind.ImplicitObjectCreationExpression))
+#endif
+            {
+                return false;
+            }
+
             // cannot use implicit typing on method group or on dynamic
             var declaredType = semanticModel.GetTypeInfo(typeName.StripRefIfNeeded(), cancellationToken).Type;
             if (declaredType != null && declaredType.TypeKind == TypeKind.Dynamic)
-- 
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