Merge pull request #4952 from tamasvajk/feature/type-mention-nullable

C#: Fix type mention extraction of named types with nullability enabled

csharp/extractor/Semmle.Extraction.CSharp/SymbolExtensions.cs

@@ -497,13 +497,13 @@ namespace Semmle.Extraction.CSharp
         /// <summary>
         /// Holds if this symbol is a source declaration.
         /// </summary>
-        public static bool IsSourceDeclaration(this ISymbol symbol) => SymbolEqualityComparer.Default.Equals(symbol, symbol.OriginalDefinition);
+        public static bool IsSourceDeclaration(this ISymbol symbol) => SymbolEqualityComparer.IncludeNullability.Equals(symbol, symbol.OriginalDefinition);
 
         /// <summary>
         /// Holds if this method is a source declaration.
         /// </summary>
         public static bool IsSourceDeclaration(this IMethodSymbol method) =>
-            IsSourceDeclaration((ISymbol)method) && SymbolEqualityComparer.Default.Equals(method, method.ConstructedFrom) && method.ReducedFrom == null;
+            IsSourceDeclaration((ISymbol)method) && SymbolEqualityComparer.IncludeNullability.Equals(method, method.ConstructedFrom) && method.ReducedFrom == null;
 
         /// <summary>
         /// Holds if this parameter is a source declaration.

csharp/ql/test/library-tests/typeMentions/NullableDisabled.cs

@@ -0,0 +1,22 @@
+using System;
+
+#nullable disable
+
+public class Base { }
+public class Derived : Base { }
+public interface I0 { }
+public interface I1 : I0 { }
+public struct Str : I1 { }
+
+public class C1
+{
+    public void M1()
+    {
+        Derived? d0 = new Derived();
+        Derived d1 = new Derived();
+        Str? s0 = new Str();
+        Str s1 = new Str();
+        I1? i0 = new Str();
+        I1 i1 = new Str();
+    }
+}

csharp/ql/test/library-tests/typeMentions/NullableEnabled.cs

@@ -0,0 +1,24 @@
+using System;
+
+#nullable enable
+
+public class Base { }
+public class Derived : Base { }
+public interface I0 { }
+public interface I1 : I0 { }
+public struct Str : I1 { }
+
+public class C1
+{
+    public void M1()
+    {
+        Derived? d0 = new Derived();
+        Derived d1 = new Derived();
+        Str? s0 = new Str();
+        Str s1 = new Str();
+        I1? i0 = new Str();
+        I1 i1 = new Str();
+    }
+}
+
+// semmle-extractor-options: --separate-compilation

csharp/ql/test/library-tests/typeMentions/TypeMentions.expected

@@ -0,0 +1,37 @@
+typeMentions
+| NullableDisabled.cs:6:24:6:27 | Base |
+| NullableDisabled.cs:8:23:8:24 | I0 |
+| NullableDisabled.cs:9:21:9:22 | I1 |
+| NullableDisabled.cs:13:12:13:15 | Void |
+| NullableDisabled.cs:15:9:15:15 | Derived |
+| NullableDisabled.cs:15:27:15:33 | Derived |
+| NullableDisabled.cs:16:9:16:15 | Derived |
+| NullableDisabled.cs:16:26:16:32 | Derived |
+| NullableDisabled.cs:17:9:17:11 | Str |
+| NullableDisabled.cs:17:9:17:12 | Nullable<Str> |
+| NullableDisabled.cs:17:23:17:25 | Str |
+| NullableDisabled.cs:18:9:18:11 | Str |
+| NullableDisabled.cs:18:22:18:24 | Str |
+| NullableDisabled.cs:19:9:19:10 | I1 |
+| NullableDisabled.cs:19:22:19:24 | Str |
+| NullableDisabled.cs:20:9:20:10 | I1 |
+| NullableDisabled.cs:20:21:20:23 | Str |
+| NullableEnabled.cs:6:24:6:27 | Base |
+| NullableEnabled.cs:8:23:8:24 | I0 |
+| NullableEnabled.cs:9:21:9:22 | I1 |
+| NullableEnabled.cs:13:12:13:15 | Void |
+| NullableEnabled.cs:15:9:15:15 | Derived |
+| NullableEnabled.cs:15:27:15:33 | Derived |
+| NullableEnabled.cs:16:9:16:15 | Derived |
+| NullableEnabled.cs:16:26:16:32 | Derived |
+| NullableEnabled.cs:17:9:17:11 | Str |
+| NullableEnabled.cs:17:9:17:12 | Nullable<Str> |
+| NullableEnabled.cs:17:23:17:25 | Str |
+| NullableEnabled.cs:18:9:18:11 | Str |
+| NullableEnabled.cs:18:22:18:24 | Str |
+| NullableEnabled.cs:19:9:19:10 | I1 |
+| NullableEnabled.cs:19:22:19:24 | Str |
+| NullableEnabled.cs:20:9:20:10 | I1 |
+| NullableEnabled.cs:20:21:20:23 | Str |
+duplicates
+diff

csharp/ql/test/library-tests/typeMentions/TypeMentions.ql

@@ -0,0 +1,29 @@
+import csharp
+
+private predicate matchingLineLoc(TypeMention tm0, TypeMention tm1) {
+  tm0.getLocation().getStartLine() = tm1.getLocation().getStartLine() and
+  tm0.getLocation().getEndLine() = tm1.getLocation().getEndLine() and
+  tm0.getLocation().getStartColumn() = tm1.getLocation().getStartColumn() and
+  tm0.getLocation().getEndColumn() = tm1.getLocation().getEndColumn()
+}
+
+private predicate matchingFile(TypeMention tm0, TypeMention tm1) {
+  tm0.getLocation().getFile().getStem() = tm1.getLocation().getFile().getStem()
+}
+
+query predicate typeMentions(TypeMention tm) { any() }
+
+query predicate duplicates(TypeMention tm) {
+  exists(TypeMention other |
+    matchingLineLoc(other, tm) and
+    matchingFile(other, tm) and
+    other != tm
+  )
+}
+
+query predicate diff(TypeMention tm) {
+  not exists(TypeMention other |
+    matchingLineLoc(other, tm) and
+    not matchingFile(other, tm)
+  )
+}