Enhance: Inline variable in CA1854 (IDictionary.TryGetValue)

src/NetAnalyzers/CSharp/Microsoft.NetCore.Analyzers/Performance/CSharpPreferDictionaryTryMethodsOverContainsKeyGuardFixer.cs

@@ -58,19 +58,26 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
             var dictionaryAccessors = new List<SyntaxNode>();
             ExpressionStatementSyntax? addStatementNode = null;
             SyntaxNode? changedValueNode = null;
+            string? valueName = null;
+            LocalDeclarationStatementSyntax? localDeclarationStatement = null;
+            VariableDeclaratorSyntax? variableDeclarator = null;
+            var additionalNodes = 0;
+            SyntaxNode? typeNode = null;
             foreach (var location in diagnostic.AdditionalLocations)
             {
                 var node = root.FindNode(location.SourceSpan, getInnermostNodeForTie: true);
                 switch (node)
                 {
                     case ElementAccessExpressionSyntax:
                         dictionaryAccessors.Add(node);
+                        typeNode ??= node;
                         break;
                     case ExpressionStatementSyntax exp:
                         if (addStatementNode != null)
                             return null;
 
                         addStatementNode = exp;
+                        additionalNodes++;
                         switch (addStatementNode.Expression)
                         {
                             case AssignmentExpressionSyntax assign:
@@ -83,15 +90,34 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                                 return null;
                         }
 
+                        break;
+                    case LocalDeclarationStatementSyntax local:
+                        localDeclarationStatement = local;
+                        valueName = local.Declaration.Variables[0].Identifier.ValueText;
+                        additionalNodes++;
+                        typeNode ??= local.Declaration.Type;
+                        break;
+                    case VariableDeclaratorSyntax
+                    {
+                        Parent: VariableDeclarationSyntax
+                        {
+                            Parent: LocalDeclarationStatementSyntax local
+                        }
+                    } declarator:
+                        variableDeclarator = declarator;
+                        localDeclarationStatement = local;
+                        valueName = declarator.Identifier.ValueText;
+                        additionalNodes++;
+                        typeNode ??= local.Declaration.Type;
                         break;
                 }
             }
 
-            if (diagnostic.AdditionalLocations.Count != dictionaryAccessors.Count + (addStatementNode != null ? 1 : 0))
+            if (diagnostic.AdditionalLocations.Count != dictionaryAccessors.Count + additionalNodes)
                 return null;
 
             var model = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
-            var type = model.GetTypeInfo(dictionaryAccessors[0], cancellationToken).Type;
+            var type = model.GetTypeInfo(typeNode!, cancellationToken).Type;
 
             return CodeAction.Create(PreferDictionaryTryGetValueCodeFixTitle, async ct =>
             {
@@ -122,13 +148,13 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                 var outArgument = generator.Argument(RefKind.Out,
                     DeclarationExpression(
                         typeSyntax,
-                        SingleVariableDesignation(Identifier(Value))
+                        SingleVariableDesignation(Identifier(valueName ?? Value))
                     )
                 );
                 var tryGetValueInvocation = generator.InvocationExpression(tryGetValueAccess, keyArgument, outArgument);
                 editor.ReplaceNode(containsKeyInvocation, tryGetValueInvocation);
 
-                var identifierName = (IdentifierNameSyntax)generator.IdentifierName(Value);
+                var identifierName = (IdentifierNameSyntax)generator.IdentifierName(valueName ?? Value);
                 if (addStatementNode != null)
                 {
                     editor.InsertBefore(addStatementNode,
@@ -160,6 +186,18 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                     }
                 }
 
+                if (localDeclarationStatement is not null)
+                {
+                    if (variableDeclarator is null)
+                    {
+                        editor.RemoveNode(localDeclarationStatement);
+                    }
+                    else
+                    {
+                        editor.RemoveNode(variableDeclarator);
+                    }
+                }
+
                 return editor.GetChangedDocument();
             }, PreferDictionaryTryGetValueCodeFixTitle);
         }

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/Performance/PreferDictionaryTryMethodsOverContainsKeyGuardAnalyzer.cs

@@ -368,6 +368,20 @@ private static bool FindUsages(IOperation operation, ref DictionaryUsageContext
                                 case IIncrementOrDecrementOperation inc when inc.Target == indexer &&
                                                                              inc.Parent is not IExpressionStatementOperation:
                                     return false;
+                                case IVariableInitializerOperation
+                                {
+                                    Parent: IVariableDeclaratorOperation
+                                    {
+                                        Parent: IVariableDeclarationOperation
+                                        {
+                                            Parent: IVariableDeclarationGroupOperation declarationGroup
+                                        } declaration
+                                    } declarator
+                                } init when init.Value == indexer:
+                                    usageContext.UsageLocations.Add(declaration.Children.Count() is 1
+                                        ? declarationGroup.Syntax.GetLocation()
+                                        : declarator.Syntax.GetLocation());
+                                    continue;
                             }
 
                             usageContext.UsageLocations.Add(indexer.Syntax.GetLocation());

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/Performance/PreferDictionaryTryMethodsOverContainsKeyGuardFixer.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.CodeFixes;

src/NetAnalyzers/UnitTests/Microsoft.NetCore.Analyzers/Performance/PreferDictionaryTryGetValueMethodsTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System.Collections.Generic;
 using System.Globalization;
@@ -463,6 +463,41 @@ bool GetDict(out IDictionary<string, int> dict)
 
             return 0;";
 
+        private const string GuardedInlineVariable = @"
+            string key = ""key"";
+            var data = new Dictionary<string, string>();
+            if ({|#0:data.ContainsKey(key)|})
+            {
+                {|#1:var a = data[key];|}
+            }
+            return 0;";
+
+        private const string GuardedInlineVariableFixed = @"
+            string key = ""key"";
+            var data = new Dictionary<string, string>();
+            if (data.TryGetValue(key, out string a))
+            {
+            }
+            return 0;";
+
+        private const string GuardedInlineVariable2 = @"
+            string key = ""key"";
+            var data = new Dictionary<string, string>();
+            if ({|#0:data.ContainsKey(key)|})
+            {
+                string {|#1:a = data[key]|}, b = """";
+            }
+            return 0;";
+
+        private const string GuardedInlineVariable2Fixed = @"
+            string key = ""key"";
+            var data = new Dictionary<string, string>();
+            if (data.TryGetValue(key, out string a))
+            {
+                string b = """";
+            }
+            return 0;";
+
         #region NoDiagnostic
 
         private const string InvalidModifiedBeforeUse = @"
@@ -1225,6 +1260,8 @@ End If
         [InlineData(GuardedIndexerInSimpleAssignment, GuardedIndexerInSimpleAssignmentFixed)]
         [InlineData(GuardedIndexerInCompoundAssignment, GuardedIndexerInCompoundAssignmentFixed)]
         [InlineData(GuardedKeyInSimpleAssignment, GuardedKeyInSimpleAssignmentFixed)]
+        [InlineData(GuardedInlineVariable, GuardedInlineVariableFixed)]
+        [InlineData(GuardedInlineVariable2, GuardedInlineVariable2Fixed)]
         public Task ShouldReportDiagnostic(string codeSnippet, string fixedCodeSnippet, int additionalLocations = 1)
         {
             string testCode = CreateCSharpCode(codeSnippet);