C#: Address review comments

Author: hvitved

csharp/extractor/Semmle.Extraction.CSharp/Entities/PreprocessorDirectives/ElifDirective.cs

@@ -22,6 +22,8 @@ public override void WriteId(EscapingTextWriter trapFile)
             trapFile.WriteSubId(Context.CreateLocation(ReportingLocation));
             trapFile.Write(Symbol.IsActive);
             trapFile.Write(',');
+            trapFile.Write(Symbol.BranchTaken);
+            trapFile.Write(',');
             trapFile.Write(Symbol.ConditionValue);
             trapFile.Write(";trivia");
         }

csharp/extractor/Semmle.Extraction.CSharp/Entities/PreprocessorDirectives/ElseDirective.cs

@@ -15,6 +15,15 @@ private ElseDirective(Context cx, ElseDirectiveTriviaSyntax trivia, IfDirective
             this.index = index;
         }
 
+        public override void WriteId(EscapingTextWriter trapFile)
+        {
+            trapFile.WriteSubId(Context.CreateLocation(ReportingLocation));
+            trapFile.Write(Symbol.IsActive);
+            trapFile.Write(',');
+            trapFile.Write(Symbol.BranchTaken);
+            trapFile.Write(";trivia");
+        }
+
         protected override void PopulatePreprocessor(TextWriter trapFile)
         {
             trapFile.directive_elses(this, Symbol.BranchTaken, start, index);

csharp/extractor/Semmle.Extraction.CSharp/Entities/PreprocessorDirectives/IfDirective.cs

@@ -17,6 +17,8 @@ public override void WriteId(EscapingTextWriter trapFile)
             trapFile.WriteSubId(Context.CreateLocation(ReportingLocation));
             trapFile.Write(Symbol.IsActive);
             trapFile.Write(',');
+            trapFile.Write(Symbol.BranchTaken);
+            trapFile.Write(',');
             trapFile.Write(Symbol.ConditionValue);
             trapFile.Write(";trivia");
         }

csharp/extractor/Semmle.Extraction.CSharp/Extractor/Analyser.cs

@@ -214,9 +214,9 @@ private void DoExtractTree(SyntaxTree tree)
                         var csNode = (CSharpSyntaxNode)root;
                         var directiveVisitor = new DirectiveVisitor(cx);
                         csNode.Accept(directiveVisitor);
-                        foreach (var condition in directiveVisitor.ActiveConditions)
+                        foreach (var branch in directiveVisitor.BranchesTaken)
                         {
-                            cx.TrapStackSuffix.Add(condition);
+                            cx.TrapStackSuffix.Add(branch);
                         }
                         csNode.Accept(new CompilationUnitVisitor(cx));
                         cx.PopulateAll();

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

@@ -9,13 +9,13 @@ namespace Semmle.Extraction.CSharp.Populators
     internal class DirectiveVisitor : CSharpSyntaxWalker
     {
         private readonly Context cx;
-        private readonly List<IEntity> activeConditions = new();
+        private readonly List<IEntity> branchesTaken = new();
 
         /// <summary>
-        /// Gets a list of `#if` and `#elif` entities that are active, and where
-        /// the condition is `true`.
+        /// Gets a list of `#if`, `#elif`, and `#else` entities where the branch
+        /// is taken.
         /// </summary>
-        public IEnumerable<IEntity> ActiveConditions => activeConditions;
+        public IEnumerable<IEntity> BranchesTaken => branchesTaken;
 
         public DirectiveVisitor(Context cx) : base(SyntaxWalkerDepth.StructuredTrivia)
         {
@@ -101,8 +101,8 @@ public override void VisitIfDirectiveTrivia(IfDirectiveTriviaSyntax node)
         {
             var ifStart = Entities.IfDirective.Create(cx, node);
             ifStarts.Push(new IfDirectiveStackElement(ifStart));
-            if (node.IsActive && node.ConditionValue)
-                activeConditions.Add(ifStart);
+            if (node.BranchTaken)
+                branchesTaken.Add(ifStart);
         }
 
         public override void VisitEndIfDirectiveTrivia(EndIfDirectiveTriviaSyntax node)
@@ -129,8 +129,8 @@ public override void VisitElifDirectiveTrivia(ElifDirectiveTriviaSyntax node)
 
             var start = ifStarts.Peek();
             var elIf = Entities.ElifDirective.Create(cx, node, start.Entity, start.SiblingCount++);
-            if (node.IsActive && node.ConditionValue)
-                activeConditions.Add(elIf);
+            if (node.BranchTaken)
+                branchesTaken.Add(elIf);
         }
 
         public override void VisitElseDirectiveTrivia(ElseDirectiveTriviaSyntax node)
@@ -143,7 +143,9 @@ public override void VisitElseDirectiveTrivia(ElseDirectiveTriviaSyntax node)
             }
 
             var start = ifStarts.Peek();
-            Entities.ElseDirective.Create(cx, node, start.Entity, start.SiblingCount++);
+            var @else = Entities.ElseDirective.Create(cx, node, start.Entity, start.SiblingCount++);
+            if (node.BranchTaken)
+                branchesTaken.Add(@else);
         }
     }
 }