Handle using var in redundant assignment removal (#75952)

Co-authored-by: Omar Bonnet <[email protected]>
dotnet · Nov 18, 2024 · 0a1a7c6 · 0a1a7c6
1 parent f6f0035
commit 0a1a7c6
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diff --git a/...nalyzers/CSharp/Tests/RemoveUnusedParametersAndValues/RemoveUnusedValueAssignmentTests.cs b/...nalyzers/CSharp/Tests/RemoveUnusedParametersAndValues/RemoveUnusedValueAssignmentTests.cs
@@ -10072,4 +10072,33 @@ public void Reset() {
             ReferenceAssemblies = ReferenceAssemblies.Net.Net80,
         }.RunAsync();
     }
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/72829")]
+    public async Task RemoveRedundantAssignment_PreservesUsingVar()
+    {
+        await TestInRegularAndScriptAsync(
+            """
+            class C
+            {
+                void M()
+                {
+                    {|FixAllInDocument:int items = 0;|}
+                    items = 42;
+                    System.Console.WriteLine(items);
+                    using var _ = System.IO.File.OpenRead("test.txt");
+                }
+            }
+            """,
+            """
+            class C
+            {
+                void M()
+                {
+                    int items = 42;
+                    System.Console.WriteLine(items);
+                    using var _ = System.IO.File.OpenRead("test.txt");
+                }
+            }
+            """);
+    }
 }
diff --git a/...rkspace/CSharp/LanguageServices/CSharpReplaceDiscardDeclarationsWithAssignmentsService.cs b/...rkspace/CSharp/LanguageServices/CSharpReplaceDiscardDeclarationsWithAssignmentsService.cs
@@ -49,6 +49,12 @@ public async Task<SyntaxNode> ReplaceAsync(
                 case LocalDeclarationStatementSyntax localDeclarationStatement:
                     if (localDeclarationStatement.Declaration.Variables.Any(IsDiscardDeclaration))
                     {
+                        // Skip replacing discard declarations in "using var"
+                        if (localDeclarationStatement.UsingKeyword != default)
+                        {
+                            continue;
+                        }
+
                         RemoveDiscardHelper.ProcessDeclarationStatement(localDeclarationStatement, editor);
                     }