C#: Add body of partial methods

Author: tamasvajk

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

@@ -80,7 +80,7 @@ void PopulateMethodBody(TextWriter trapFile)
                         else
                             Expression.Create(Context, expr, this, 0);
 
-                        Context.NumberOfLines(trapFile, symbol, this);
+                        Context.NumberOfLines(trapFile, BodyDeclaringSymbol, this);
                     });
         }
 
@@ -126,7 +126,7 @@ protected static void BuildMethodId(Method m, TextWriter trapFile)
                 {
                     trapFile.Write('<');
                     // Encode the nullability of the type arguments in the label.
-                    // Type arguments with different nullability can result in 
+                    // Type arguments with different nullability can result in
                     // a constructed method with different nullability of its parameters and return type,
                     // so we need to create a distinct database entity for it.
                     trapFile.BuildList(",", m.symbol.GetAnnotatedTypeArguments(), (ta, tb0) => { AddSignatureTypeToId(m.Context, tb0, m.symbol, ta.Symbol); trapFile.Write((int)ta.Nullability); });

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

@@ -13,6 +13,8 @@ class OrdinaryMethod : Method
 
         public override string Name => symbol.GetName();
 
+        protected override IMethodSymbol BodyDeclaringSymbol => symbol.PartialImplementationPart ?? symbol;
+
         public IMethodSymbol SourceDeclaration
         {
             get

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

@@ -95,14 +95,15 @@ protected void BindComments()
                 Context.BindComments(this, FullLocation);
         }
 
+        protected virtual T BodyDeclaringSymbol => symbol;
+
         public BlockSyntax Block
         {
             get
             {
-                return symbol.
+                return BodyDeclaringSymbol.
                     DeclaringSyntaxReferences.
-                    Select(r => r.GetSyntax()).
-                    SelectMany(n => n.ChildNodes()).
+                    SelectMany(r => r.GetSyntax().ChildNodes()).
                     OfType<BlockSyntax>().
                     FirstOrDefault();
             }
@@ -112,7 +113,7 @@ public ExpressionSyntax ExpressionBody
         {
             get
             {
-                return symbol.
+                return BodyDeclaringSymbol.
                     DeclaringSyntaxReferences.
                     SelectMany(r => r.GetSyntax().ChildNodes()).
                     OfType<ArrowExpressionClauseSyntax>().