C#: Address comments

Author: hvitved

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs

@@ -128,7 +128,7 @@ private static bool ContainsPattern(SyntaxNode node) =>
             node is PatternSyntax || node is VariableDesignationSyntax || node.ChildNodes().Any(ContainsPattern);
 
         /// <summary>
-        /// Creates a generated expression from a typed constant..
+        /// Creates a generated expression from a typed constant.
         /// </summary>
         public static Expression CreateGenerated(Context cx, TypedConstant constant, IExpressionParentEntity parent,
             int childIndex, Semmle.Extraction.Entities.Location ___location)

csharp/extractor/Semmle.Extraction.CSharp/Populators/CompilationUnit.cs

@@ -3,7 +3,9 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Semmle.Extraction.CSharp.Entities;
 using Semmle.Extraction.Entities;
+using Semmle.Util;
 using Semmle.Util.Logging;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -15,12 +17,23 @@ public class TypeContainerVisitor : CSharpSyntaxVisitor
         protected Context cx { get; }
         protected IEntity parent { get; }
         protected TextWriter trapFile { get; }
+        private readonly Lazy<Func<SyntaxNode, AttributeData>> attributeLookup;
 
         public TypeContainerVisitor(Context cx, TextWriter trapFile, IEntity parent)
         {
             this.cx = cx;
             this.parent = parent;
             this.trapFile = trapFile;
+            attributeLookup = new Lazy<Func<SyntaxNode, AttributeData>>(() =>
+                {
+                    var dict = new Dictionary<SyntaxNode, AttributeData>();
+                    foreach (var attributeData in cx.Compilation.Assembly.GetAttributes().Concat(cx.Compilation.Assembly.Modules.SelectMany(m => m.GetAttributes())))
+                    {
+                        if (attributeData.ApplicationSyntaxReference?.GetSyntax() is SyntaxNode syntax)
+                            dict.Add(syntax, attributeData);
+                    }
+                    return dict.GetValueOrDefault;
+                });
         }
 
         public override void DefaultVisit(SyntaxNode node)
@@ -59,17 +72,11 @@ public override void VisitAttributeList(AttributeListSyntax node)
                 return;
 
             var outputAssembly = Assembly.CreateOutputAssembly(cx);
-            var attributeLookup = new Dictionary<SyntaxNode, AttributeData>();
-            foreach (var attributeData in cx.Compilation.Assembly.GetAttributes().Concat(cx.Compilation.Assembly.Modules.SelectMany(m => m.GetAttributes())))
-            {
-                if (attributeData.ApplicationSyntaxReference?.GetSyntax() is SyntaxNode syntax)
-                    attributeLookup.Add(syntax, attributeData);
-            }
             foreach (var attribute in node.Attributes)
             {
-                if (attributeLookup.TryGetValue(attribute, out var attributeData))
+                if (attributeLookup.Value(attribute) is AttributeData attributeData)
                 {
-                    var ae = Attribute.Create(cx, attributeData, outputAssembly);
+                    var ae = Semmle.Extraction.CSharp.Entities.Attribute.Create(cx, attributeData, outputAssembly);
                     cx.BindComments(ae, attribute.GetLocation());
                 }
             }