Made ValueSource.Description nullable

Author: KathleenDollard

src/System.CommandLine.Subsystems/Validation/RangeValidator.cs

@@ -20,7 +20,7 @@ public override void Validate(object? value, CliValueSymbol valueSymbol,
         }
         if (valueCondition.MustHaveValidator)
         {
-            validationContext.PipelineResult.AddError(new ParseError($"Range validator missing for {valueResult.ValueSymbol.Name}"));
+            validationContext.PipelineResult.AddError(new ParseError($"Range validator missing for {valueSymbol.Name}"));
         }
     }
 

src/System.CommandLine.Subsystems/ValueSources/AggregateValueSource.cs

@@ -7,7 +7,7 @@ public class AggregateValueSource : ValueSource
 {
     private List<ValueSource> valueSources = [];
 
-    public override string Description { get; }
+    public override string? Description { get; }
 
     public override (bool success, object? value) GetValue(PipelineResult pipelineResult)
     {

src/System.CommandLine.Subsystems/ValueSources/CalculatedValueSource.cs

@@ -7,7 +7,7 @@ namespace System.CommandLine.ValueSources;
 public class CalculatedValueSource<T>(Func<(bool success, T? value)> calculation, string? description = null)
     : ValueSource<T>
 {
-    public override string Description { get; } = description;
+    public override string? Description { get; } = description;
 
     public override (bool success, T? value) GetTypedValue(PipelineResult pipelineResult)
         => calculation();

src/System.CommandLine.Subsystems/ValueSources/RelativeToEnvironmentVariableValueSource.cs

@@ -8,7 +8,7 @@ public class RelativeToEnvironmentVariableValueSource<T>(string environmentVaria
                                                          string? description = null)
     : ValueSource<T>
 {
-    public override string Description { get; } = description;
+    public override string? Description { get; } = description;
 
     public override (bool success, T? value) GetTypedValue(PipelineResult pipelineResult)
     {

src/System.CommandLine.Subsystems/ValueSources/RelativeToSymbolValueSource.cs

@@ -8,7 +8,7 @@ public class RelativeToSymbolValueSource<T>(CliValueSymbol otherSymbol,
                                             string? description = null)
     : ValueSource<T>
 {
-    public override string Description { get; } = description;
+    public override string? Description { get; } = description;
 
     public override (bool success, T? value) GetTypedValue(PipelineResult pipelineResult)
         => calculation is null

src/System.CommandLine.Subsystems/ValueSources/SimpleValueSource.cs

@@ -6,7 +6,7 @@ namespace System.CommandLine.ValueSources;
 public class SimpleValueSource<T>(T value, string? description = null)
     : ValueSource<T>
 {
-    public override string Description { get; } = description;
+    public override string? Description { get; } = description;
 
     public override (bool success, T? value) GetTypedValue(PipelineResult pipelineResult)
         => (true, value);

src/System.CommandLine.Subsystems/ValueSources/ValueSource.cs

@@ -8,7 +8,7 @@ public abstract class ValueSource
     public abstract (bool success, object? value) GetValue(PipelineResult pipelineResult);
 
     // TODO: Should we use ToString() here?
-    public abstract string Description { get; }
+    public abstract string? Description { get; }
     public static ValueSource<T> Create<T>(T value, string? description = null)
         => new SimpleValueSource<T>(value, description);