[Fusion] Remove descriptions from field definitions in @fusion__ directives (#8679)

Author: tobias-tengler

src/HotChocolate/Fusion-vnext/src/Fusion.Composition/SourceSchemaMerger.cs

@@ -24,7 +24,7 @@ namespace HotChocolate.Fusion;
 
 internal sealed class SourceSchemaMerger
 {
-    private static readonly RemoveDirectiveNodesSyntaxRewriter s_removeDirectivesRewriter = new();
+    private static readonly FusionFieldDefinitionSyntaxRewriter s_fieldDefinitionRewriter = new();
     private readonly ImmutableSortedSet<MutableSchemaDefinition> _schemas;
     private readonly FrozenDictionary<MutableSchemaDefinition, string> _schemaConstantNames;
     private readonly SourceSchemaMergerOptions _options;
@@ -1026,7 +1026,7 @@ private void AddFusionLookupDirectives(
                 mergedSelectionSet.ToString(indented: false).AsSpan()[2..^2].ToString();
 
             var fieldArgument =
-                s_removeDirectivesRewriter
+                s_fieldDefinitionRewriter
                     .Rewrite(sourceField.ToSyntaxNode())!
                     .ToString(indented: false);
 
@@ -1111,7 +1111,7 @@ private void AddFusionRequiresDirectives(
                     mergedSelectionSet.ToString(indented: false).AsSpan()[2..^2].ToString();
 
                 var fieldArgument =
-                    s_removeDirectivesRewriter
+                    s_fieldDefinitionRewriter
                         .Rewrite(sourceField.ToSyntaxNode())!
                         .ToString(indented: false);
 

src/HotChocolate/Fusion-vnext/src/Fusion.Utilities/SyntaxRewriters/FusionFieldDefinitionSyntaxRewriter.cs

@@ -0,0 +1,30 @@
+using HotChocolate.Language;
+using HotChocolate.Language.Visitors;
+
+namespace HotChocolate.Fusion.SyntaxRewriters;
+
+/// <summary>
+/// Rewrites a field definition to remove any directives and descriptions.
+/// </summary>
+public sealed class FusionFieldDefinitionSyntaxRewriter : SyntaxRewriter<object?>
+{
+    protected override DirectiveNode? RewriteDirective(DirectiveNode node, object? context)
+    {
+        return null;
+    }
+
+    protected override FieldDefinitionNode? RewriteFieldDefinition(FieldDefinitionNode node, object? context)
+    {
+        var rewrittenNode = base.RewriteFieldDefinition(node, context);
+        return rewrittenNode?.WithDescription(null);
+    }
+
+    protected override InputValueDefinitionNode? RewriteInputValueDefinition(
+        InputValueDefinitionNode node,
+        object? context)
+    {
+        var rewrittenNode = base.RewriteInputValueDefinition(node, context);
+
+        return rewrittenNode?.WithDescription(null);
+    }
+}

src/HotChocolate/Fusion-vnext/src/Fusion.Utilities/SyntaxRewriters/RemoveDirectiveNodesSyntaxRewriter.cs

@@ -569,6 +569,41 @@ type Product
                         @fusion__field(schema: A)
                 }
                 """
+            },
+            // Lookup field and argument have a description
+            {
+                [
+                    """
+                    type Query {
+                        "Fetches a product"
+                        productById("The product id" id: ID!): Product @lookup
+                    }
+
+                    type Product @key(fields: "id") {
+                        id: ID!
+                    }
+                    """
+                ],
+                """
+                schema {
+                  query: Query
+                }
+
+                type Query
+                  @fusion__type(schema: A) {
+                  "Fetches a product"
+                  productById("The product id" id: ID!
+                    @fusion__inputField(schema: A)): Product
+                    @fusion__field(schema: A)
+                }
+
+                type Product
+                  @fusion__type(schema: A)
+                  @fusion__lookup(schema: A, key: "id", field: "productById(id: ID!): Product", map: [ "id" ], path: null, internal: false) {
+                  id: ID!
+                    @fusion__field(schema: A)
+                }
+                """
             }
         };
     }