C#: Add support for init only accessors

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

@@ -76,6 +76,11 @@ namespace Semmle.Extraction.CSharp.Entities
             {
                 trapFile.compiler_generated(this);
             }
+
+            if (symbol.IsInitOnly)
+            {
+                trapFile.init_only_accessors(this);
+            }
         }
 
         public static new Accessor Create(Context cx, IMethodSymbol symbol) =>

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

@@ -26,6 +26,11 @@ namespace Semmle.Extraction.CSharp
             trapFile.WriteTuple("accessors", accessorKey, kind, name, propKey, unboundAccessor);
         }
 
+        internal static void init_only_accessors(this TextWriter trapFile, Accessor accessorKey)
+        {
+            trapFile.WriteTuple("init_only_accessors", accessorKey);
+        }
+
         internal static void array_element_type(this TextWriter trapFile, ArrayType array, int dimension, int rank, Type elementType)
         {
             trapFile.WriteTuple("array_element_type", array, dimension, rank, elementType);

csharp/ql/src/semmle/code/csharp/Property.qll

@@ -472,6 +472,9 @@ class Setter extends Accessor, @setter {
     result = Accessor.super.getDeclaration()
   }
 
+  /** Holds if this setter is an `init`-only accessor. */
+  predicate isInitOnly() { init_only_accessors(this) }
+
   override string getAPrimaryQlClass() { result = "Setter" }
 }
 

csharp/ql/src/semmlecode.csharp.dbscheme

@@ -604,6 +604,9 @@ case @accessor.kind of
 | 2 = @setter
   ;
 
+init_only_accessors(
+  unique int id: @accessor ref);
+
 accessor_location(
   int id: @accessor ref,
   int loc: @location ref);

csharp/ql/test/library-tests/csharp9/InitOnlyProperty.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    public sealed class IsExternalInit
+    {
+    }
+}
+
+public class Base
+{
+    public int Prop0 { get { return 1; } init { Prop1 = value; } }
+    public virtual int Prop1 { get; init; }
+    public virtual int Prop2 { get; set; }
+
+}
+
+public class Derived : Base
+{
+    public override int Prop1 { get; init; }
+    public int Prop2
+    {
+        get { return 0; }
+        init
+        {
+            System.Console.WriteLine(value);
+            Prop1 = value;
+            Prop0 = value;
+        }
+    }
+}
+
+public class C1
+{
+    public void M1()
+    {
+        var d = new Derived
+        {
+            Prop1 = 1,
+            Prop2 = 2,
+            Prop0 = 0
+        };
+    }
+}

csharp/ql/test/library-tests/csharp9/PrintAst.expected

@@ -47,6 +47,88 @@ Discard.cs:
 #   10|             4: [BlockStmt] {...}
 #   10|               0: [ReturnStmt] return ...;
 #   10|                 0: [IntLiteral] 0
+InitOnlyProperty.cs:
+#    3| [NamespaceDeclaration] namespace ... { ... }
+#    5|   1: [Class] IsExternalInit
+#   10| [Class] Base
+#   12|   5: [Property] Prop0
+#   12|     -1: [TypeMention] int
+#   12|     3: [Getter] get_Prop0
+#   12|       4: [BlockStmt] {...}
+#   12|         0: [ReturnStmt] return ...;
+#   12|           0: [IntLiteral] 1
+#   12|     4: [Setter] set_Prop0
+#-----|       2: (Parameters)
+#   12|         0: [Parameter] value
+#   12|       4: [BlockStmt] {...}
+#   12|         0: [ExprStmt] ...;
+#   12|           0: [AssignExpr] ... = ...
+#   12|             0: [PropertyCall] access to property Prop1
+#   12|             1: [ParameterAccess] access to parameter value
+#   13|   6: [Property] Prop1
+#   13|     -1: [TypeMention] int
+#   13|     3: [Getter] get_Prop1
+#   13|     4: [Setter] set_Prop1
+#-----|       2: (Parameters)
+#   13|         0: [Parameter] value
+#   14|   7: [Property] Prop2
+#   14|     -1: [TypeMention] int
+#   14|     3: [Getter] get_Prop2
+#   14|     4: [Setter] set_Prop2
+#-----|       2: (Parameters)
+#   14|         0: [Parameter] value
+#   18| [Class] Derived
+#-----|   3: (Base types)
+#   18|     0: [TypeMention] Base
+#   20|   5: [Property] Prop1
+#   20|     -1: [TypeMention] int
+#   20|     3: [Getter] get_Prop1
+#   20|     4: [Setter] set_Prop1
+#-----|       2: (Parameters)
+#   20|         0: [Parameter] value
+#   21|   6: [Property] Prop2
+#   21|     -1: [TypeMention] int
+#   23|     3: [Getter] get_Prop2
+#   23|       4: [BlockStmt] {...}
+#   23|         0: [ReturnStmt] return ...;
+#   23|           0: [IntLiteral] 0
+#   24|     4: [Setter] set_Prop2
+#-----|       2: (Parameters)
+#   24|         0: [Parameter] value
+#   25|       4: [BlockStmt] {...}
+#   26|         0: [ExprStmt] ...;
+#   26|           0: [MethodCall] call to method WriteLine
+#   26|             -1: [TypeAccess] access to type Console
+#   26|               0: [TypeMention] Console
+#   26|             0: [ParameterAccess] access to parameter value
+#   27|         1: [ExprStmt] ...;
+#   27|           0: [AssignExpr] ... = ...
+#   27|             0: [PropertyCall] access to property Prop1
+#   27|             1: [ParameterAccess] access to parameter value
+#   28|         2: [ExprStmt] ...;
+#   28|           0: [AssignExpr] ... = ...
+#   28|             0: [PropertyCall] access to property Prop0
+#   28|             1: [ParameterAccess] access to parameter value
+#   33| [Class] C1
+#   35|   5: [Method] M1
+#   35|     -1: [TypeMention] Void
+#   36|     4: [BlockStmt] {...}
+#   37|       0: [LocalVariableDeclStmt] ... ...;
+#   37|         0: [LocalVariableDeclAndInitExpr] Derived d = ...
+#   37|           -1: [TypeMention] Derived
+#   37|           0: [LocalVariableAccess] access to local variable d
+#   37|           1: [ObjectCreation] object creation of type Derived
+#   37|             -2: [TypeMention] Derived
+#   38|             -1: [ObjectInitializer] { ..., ... }
+#   39|               0: [MemberInitializer] ... = ...
+#   39|                 0: [PropertyCall] access to property Prop1
+#   39|                 1: [IntLiteral] 1
+#   40|               1: [MemberInitializer] ... = ...
+#   40|                 0: [PropertyCall] access to property Prop2
+#   40|                 1: [IntLiteral] 2
+#   41|               2: [MemberInitializer] ... = ...
+#   41|                 0: [PropertyCall] access to property Prop0
+#   41|                 1: [IntLiteral] 0
 LambdaModifier.cs:
 #    4| [Class] Class1
 #    6|   5: [Method] M1

csharp/ql/test/library-tests/csharp9/initOnlyProperty.expected

@@ -0,0 +1,5 @@
+| InitOnlyProperty.cs:12:42:12:45 | set_Prop0 | init |
+| InitOnlyProperty.cs:13:37:13:40 | set_Prop1 | init |
+| InitOnlyProperty.cs:14:37:14:39 | set_Prop2 | set |
+| InitOnlyProperty.cs:20:38:20:41 | set_Prop1 | init |
+| InitOnlyProperty.cs:24:9:24:12 | set_Prop2 | init |

csharp/ql/test/library-tests/csharp9/initOnlyProperty.ql

@@ -0,0 +1,7 @@
+import csharp
+
+private string getType(Setter s) { if s.isInitOnly() then result = "init" else result = "set" }
+
+from Setter s
+where s.fromSource()
+select s, getType(s)

csharp/upgrades/TO_CHANGE/upgrade.properties

@@ -0,0 +1,2 @@
+description: Added 'init_only_accessors' relation.
+compatibility: backwards