C#: Make @local_function @modifiable, make LocalFunction extend Modifiable, and extract modifiers for local functions.

calumgrant · calumgrant · commit 599a5b1eef0f · 2019-06-04T18:10:49.000+01:00
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/LocalFunction.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/LocalFunction.cs
@@ -1,4 +1,6 @@
 ﻿using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using System.Linq;
 
 namespace Semmle.Extraction.CSharp.Entities
 {
@@ -39,6 +41,18 @@ class LocalFunctionFactory : ICachedEntityFactory<IMethodSymbol, LocalFunction>
         public override void Populate()
         {
             PopulateMethod();
+
+            // There is a "bug" in Roslyn whereby the IMethodSymbol associated with the local function symbol
+            // is always static, so we need to go to the syntax reference of the local function to see whether
+            // the "static" modifier is present.
+            if (symbol.DeclaringSyntaxReferences.SingleOrDefault().GetSyntax() is LocalFunctionStatementSyntax fn)
+            {
+                foreach(var modifier in fn.Modifiers)
+                {
+                    Modifier.HasModifier(Context, this, modifier.Text);
+                }
+            }
+
             var originalDefinition = IsSourceDeclaration ? this : Create(Context, symbol.OriginalDefinition);
             var returnType = Type.Create(Context, symbol.ReturnType);
             Context.Emit(Tuples.local_functions(this, symbol.Name, returnType, originalDefinition));
diff --git a/csharp/ql/src/semmle/code/csharp/Callable.qll b/csharp/ql/src/semmle/code/csharp/Callable.qll
@@ -903,7 +903,7 @@ class ExplicitConversionOperator extends ConversionOperator {
  * }
  * ```
  */
-class LocalFunction extends Callable, @local_function {
+class LocalFunction extends Callable, Modifiable, @local_function {
   override string getName() { local_functions(this, result, _, _) }
 
   override LocalFunction getSourceDeclaration() { local_functions(this, _, _, result) }
diff --git a/csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.cs b/csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.cs
@@ -0,0 +1,13 @@
+// semmle-extractor-options: /langversion:8.0
+
+using System;
+
+class StaticLocalFunctions
+{
+    int Fn(int x)
+    {
+        static int I(int y) => y;
+        int J(int y) => x+y;
+        return I(x) + J(x);
+    }
+}
diff --git a/csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.expected b/csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.expected
@@ -0,0 +1 @@
+| StaticLocalFunctions.cs:9:9:9:33 | I | static |
diff --git a/csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.ql b/csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.ql
@@ -0,0 +1,5 @@
+import csharp
+
+from LocalFunction fn, string modifier
+where fn.hasModifier(modifier)
+select fn, modifier

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+\| StaticLocalFunctions.cs:9:9:9:33 \| I \| static \|`