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Unused Symbol Detection

Identify and eliminate dead code with unused symbol highlighting.

Overview​

Unused symbol detection automatically highlights code that isn't being used anywhere in your project.

What Gets Detected​

Private Methods​

Private methods with no references:

private void UnusedMethod() // Appears grayed out
{
    // This method is never called
}

Properties​

Public and private properties not accessed:

private string UnusedProperty { get; set; } // Grayed out

Fields​

Fields that are declared but never used:

private int _unusedField; // Grayed out

Events​

Events that are never subscribed to or raised:

private event EventHandler UnusedEvent; // Grayed out

Visual Indication​

Unused symbols appear with reduced opacity (grayed out), making them easy to spot.

Configuration​

Enable/Disable​

  1. Open Settings (Ctrl+,)
  2. Search for csharp-dev-tools.editor.highlightUnusedSymbols
  3. Toggle on/off

Or use Command Palette: "Toggle Unused Symbol Highlighting"

Adjust Opacity​

Control how grayed out unused symbols appear:

  1. Search for csharp-dev-tools.editor.unusedSymbolOpacity
  2. Set value between 0.1 (very faint) and 1.0 (normal)

Detection Method​

The extension uses:

  1. Primary: C# Language Server diagnostics (IDE0051, etc.)
  2. Fallback: Reference counting for larger files
  3. Scope: File-level detection for performance

Exclusions​

Public Methods​

Public methods are excluded from detection as they might be:

  • API endpoints
  • Library methods
  • Called from external projects
  • Used via reflection

Interface Implementations​

Methods implementing interfaces are excluded even if not directly called.

Virtual/Override Methods​

Virtual and override methods are excluded as they may be called via polymorphism.

Use Cases​

Code Cleanup​

  • Identify methods to remove
  • Find unused properties
  • Eliminate dead code
  • Reduce technical debt

Refactoring​

  • Safely remove unused code
  • Simplify classes
  • Improve maintainability

Code Review​

  • Spot accidentally unused code
  • Find leftover experimental code
  • Identify incomplete refactorings

Best Practices​

  • Review grayed out code before deleting
  • Check if code is intentionally unused (future use)
  • Consider making unused public methods private
  • Remove truly dead code to reduce complexity

Troubleshooting​

False Positives​

If actively used code appears unused:

  • May be called via reflection
  • Used in other projects/assemblies
  • Called from markup (Blazor, XAML)
  • Toggle off the feature for those files

Not Detecting Unused Code​

  • Ensure C# Language Server is running
  • Check file is part of project
  • Verify diagnostic level includes information
  • Rebuild project if needed

Performance​

  • Lightweight detection
  • Incremental updates
  • Optimized for large files
  • Minimal performance impact