C#: Cache the Block and ExpressionBody and streamline implementation too look for both when checking whether a body is available.

Author: michaelnebel

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

@@ -70,7 +70,7 @@ public override void Populate(TextWriter trapFile)
 
             Overrides(trapFile);
 
-            if (Symbol.FromSource() && Block is null)
+            if (Symbol.FromSource() && !HasBody)
             {
                 trapFile.compiler_generated(this);
             }

csharp/extractor/Semmle.Extraction.CSharp/Entities/Base/CachedSymbol.cs

@@ -9,9 +9,14 @@ namespace Semmle.Extraction.CSharp.Entities
 {
     internal abstract class CachedSymbol<T> : CachedEntity<T> where T : class, ISymbol
     {
+        private readonly Lazy<BlockSyntax?> blockLazy;
+        private readonly Lazy<ExpressionSyntax?> expressionBodyLazy;
+
         protected CachedSymbol(Context cx, T init)
             : base(cx, init)
         {
+            blockLazy = new Lazy<BlockSyntax?>(() => GetBlock(BodyDeclaringSymbol));
+            expressionBodyLazy = new Lazy<ExpressionSyntax?>(() => GetExpressionBody(BodyDeclaringSymbol));
         }
 
         public virtual Type? ContainingType => Symbol.ContainingType is not null
@@ -89,29 +94,29 @@ protected void BindComments()
 
         protected virtual T BodyDeclaringSymbol => Symbol;
 
-        public BlockSyntax? Block
+        private static BlockSyntax? GetBlock(T symbol)
         {
-            get
-            {
-                return BodyDeclaringSymbol.DeclaringSyntaxReferences
+            return symbol.DeclaringSyntaxReferences
                     .SelectMany(r => r.GetSyntax().ChildNodes())
                     .OfType<BlockSyntax>()
                     .FirstOrDefault();
-            }
         }
 
-        public ExpressionSyntax? ExpressionBody
+        private static ExpressionSyntax? GetExpressionBody(T symbol)
         {
-            get
-            {
-                return BodyDeclaringSymbol.DeclaringSyntaxReferences
+            return symbol.DeclaringSyntaxReferences
                     .SelectMany(r => r.GetSyntax().ChildNodes())
                     .OfType<ArrowExpressionClauseSyntax>()
                     .Select(arrow => arrow.Expression)
                     .FirstOrDefault();
-            }
         }
 
+        public BlockSyntax? Block => blockLazy.Value;
+
+        public ExpressionSyntax? ExpressionBody => expressionBodyLazy.Value;
+
+        public bool HasBody => Block is not null || ExpressionBody is not null;
+
         public virtual bool IsSourceDeclaration => Symbol.IsSourceDeclaration();
 
         public override bool NeedsPopulation => Context.Defines(Symbol);

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

@@ -42,7 +42,7 @@ public override void Populate(TextWriter trapFile)
                 return;
             }
 
-            if (MakeSynthetic)
+            if (MakeSyntheticBody)
             {
                 // Create a synthetic empty body for primary and default constructors.
                 Statements.SyntheticEmptyBlock.Create(Context, this, 0, Location);
@@ -60,7 +60,7 @@ protected override void ExtractInitializers(TextWriter trapFile)
             // Do not extract initializers for constructed types.
             // Extract initializers for constructors with a body, primary constructors
             // and default constructors for classes and structs declared in source code.
-            if (Block is null && ExpressionBody is null && !MakeSynthetic || Context.OnlyScaffold)
+            if (!HasBody && !MakeSyntheticBody || Context.OnlyScaffold)
             {
                 return;
             }
@@ -211,7 +211,7 @@ Symbol.ContainingType.TypeKind is TypeKind.Class or TypeKind.Struct &&
         /// </summary>
         private bool IsBestSourceLocation => ReportingLocation is not null && Context.IsLocationInContext(ReportingLocation);
 
-        private bool MakeSynthetic => (IsPrimary || (IsDefault && IsBestSourceLocation)) && !Context.OnlyScaffold;
+        private bool MakeSyntheticBody => (IsPrimary || (IsDefault && IsBestSourceLocation)) && !Context.OnlyScaffold;
 
         [return: NotNullIfNotNull(nameof(constructor))]
         public static new Constructor? Create(Context cx, IMethodSymbol? constructor)

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

@@ -59,7 +59,7 @@ public override void Populate(TextWriter trapFile)
 
             Overrides(trapFile);
 
-            if (Symbol.FromSource() && Block is null)
+            if (Symbol.FromSource() && !HasBody)
             {
                 trapFile.compiler_generated(this);
             }