C#: Teach guards library about object.GetType()

Author: hvitved

csharp/ql/src/semmle/code/csharp/controlflow/Guards.qll

@@ -682,6 +682,11 @@ module Internal {
     or
     e instanceof AddExpr and
     e.getType() instanceof StringType
+    or
+    e = any(MethodCall mc |
+      mc.getTarget() = any(SystemObjectClass c).getGetTypeMethod() and
+      not mc.isConditional()
+    )
   }
 
   /** Holds if expression `e2` is a non-`null` value whenever `e1` is. */

csharp/ql/test/library-tests/controlflow/guards/BooleanGuardedExpr.expected

@@ -68,6 +68,8 @@
 | Guards.cs:198:31:198:31 | access to parameter s | Guards.cs:197:14:197:29 | call to method NullTestWrong | Guards.cs:197:28:197:28 | access to parameter s | false |
 | Guards.cs:205:13:205:13 | access to parameter o | Guards.cs:203:13:203:21 | ... != ... | Guards.cs:203:13:203:13 | access to parameter o | true |
 | Guards.cs:208:17:208:17 | access to parameter o | Guards.cs:203:13:203:21 | ... != ... | Guards.cs:203:13:203:13 | access to parameter o | true |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:13:268:41 | call to operator == | Guards.cs:268:13:268:14 | access to parameter o1 | true |
+| Guards.cs:271:11:271:12 | access to parameter o1 | Guards.cs:270:13:270:42 | call to operator == | Guards.cs:270:13:270:14 | access to parameter o1 | true |
 | Splitting.cs:13:17:13:17 | access to parameter o | Splitting.cs:12:17:12:25 | ... != ... | Splitting.cs:12:17:12:17 | access to parameter o | true |
 | Splitting.cs:23:24:23:24 | access to parameter o | Splitting.cs:22:17:22:25 | ... != ... | Splitting.cs:22:17:22:17 | access to parameter o | true |
 | Splitting.cs:25:13:25:13 | access to parameter o | Splitting.cs:22:17:22:25 | ... != ... | Splitting.cs:22:17:22:17 | access to parameter o | false |

csharp/ql/test/library-tests/controlflow/guards/GuardedControlFlowNode.expected

@@ -164,6 +164,10 @@
 | Guards.cs:205:13:205:13 | access to parameter o | Guards.cs:203:13:203:21 | ... != ... | Guards.cs:203:13:203:13 | access to parameter o | true |
 | Guards.cs:208:17:208:17 | access to parameter o | Guards.cs:203:13:203:13 | access to parameter o | Guards.cs:203:13:203:13 | access to parameter o | non-null |
 | Guards.cs:208:17:208:17 | access to parameter o | Guards.cs:203:13:203:21 | ... != ... | Guards.cs:203:13:203:13 | access to parameter o | true |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:13:268:14 | access to parameter o1 | Guards.cs:268:13:268:14 | access to parameter o1 | non-null |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:13:268:41 | call to operator == | Guards.cs:268:13:268:14 | access to parameter o1 | true |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:16:268:25 | call to method GetType | Guards.cs:268:13:268:14 | access to parameter o1 | non-null |
+| Guards.cs:271:11:271:12 | access to parameter o1 | Guards.cs:270:13:270:42 | call to operator == | Guards.cs:270:13:270:14 | access to parameter o1 | true |
 | Splitting.cs:13:17:13:17 | [b (line 9): true] access to parameter o | Splitting.cs:12:17:12:17 | access to parameter o | Splitting.cs:12:17:12:17 | access to parameter o | non-null |
 | Splitting.cs:13:17:13:17 | [b (line 9): true] access to parameter o | Splitting.cs:12:17:12:25 | ... != ... | Splitting.cs:12:17:12:17 | access to parameter o | true |
 | Splitting.cs:14:13:14:13 | [b (line 9): false] access to parameter b | Splitting.cs:11:13:11:13 | access to parameter b | Splitting.cs:11:13:11:13 | access to parameter b | false |

csharp/ql/test/library-tests/controlflow/guards/GuardedExpr.expected

@@ -164,6 +164,10 @@
 | Guards.cs:205:13:205:13 | access to parameter o | Guards.cs:203:13:203:21 | ... != ... | Guards.cs:203:13:203:13 | access to parameter o | true |
 | Guards.cs:208:17:208:17 | access to parameter o | Guards.cs:203:13:203:13 | access to parameter o | Guards.cs:203:13:203:13 | access to parameter o | non-null |
 | Guards.cs:208:17:208:17 | access to parameter o | Guards.cs:203:13:203:21 | ... != ... | Guards.cs:203:13:203:13 | access to parameter o | true |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:13:268:14 | access to parameter o1 | Guards.cs:268:13:268:14 | access to parameter o1 | non-null |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:13:268:41 | call to operator == | Guards.cs:268:13:268:14 | access to parameter o1 | true |
+| Guards.cs:269:11:269:12 | access to parameter o1 | Guards.cs:268:16:268:25 | call to method GetType | Guards.cs:268:13:268:14 | access to parameter o1 | non-null |
+| Guards.cs:271:11:271:12 | access to parameter o1 | Guards.cs:270:13:270:42 | call to operator == | Guards.cs:270:13:270:14 | access to parameter o1 | true |
 | Splitting.cs:13:17:13:17 | access to parameter o | Splitting.cs:12:17:12:17 | access to parameter o | Splitting.cs:12:17:12:17 | access to parameter o | non-null |
 | Splitting.cs:13:17:13:17 | access to parameter o | Splitting.cs:12:17:12:25 | ... != ... | Splitting.cs:12:17:12:17 | access to parameter o | true |
 | Splitting.cs:23:24:23:24 | access to parameter o | Splitting.cs:22:17:22:17 | access to parameter o | Splitting.cs:22:17:22:17 | access to parameter o | non-null |

csharp/ql/test/library-tests/controlflow/guards/Implications.expected

@@ -345,6 +345,10 @@
 | Guards.cs:258:17:258:17 | access to local variable e | match case ...: | Guards.cs:256:13:256:13 | access to parameter b | true |
 | Guards.cs:258:17:258:17 | access to local variable e | match case ...: | Guards.cs:258:17:258:17 | access to local variable e | 1 |
 | Guards.cs:258:17:258:17 | access to local variable e | non-match case ...: | Guards.cs:256:13:256:13 | access to parameter b | false |
+| Guards.cs:268:13:268:41 | call to operator == | true | Guards.cs:268:16:268:25 | call to method GetType | non-null |
+| Guards.cs:268:16:268:25 | call to method GetType | non-null | Guards.cs:268:13:268:14 | access to parameter o1 | non-null |
+| Guards.cs:270:16:270:25 | call to method GetType | non-null | Guards.cs:270:13:270:14 | access to parameter o1 | non-null |
+| Guards.cs:270:33:270:42 | call to method GetType | non-null | Guards.cs:270:30:270:31 | access to parameter o2 | non-null |
 | Splitting.cs:12:17:12:25 | ... != ... | false | Splitting.cs:12:17:12:17 | access to parameter o | null |
 | Splitting.cs:12:17:12:25 | ... != ... | true | Splitting.cs:12:17:12:17 | access to parameter o | non-null |
 | Splitting.cs:22:17:22:25 | ... != ... | false | Splitting.cs:22:17:22:17 | access to parameter o | null |

csharp/ql/test/library-tests/controlflow/guards/NullGuardedExpr.expected

@@ -41,6 +41,7 @@
 | Guards.cs:196:31:196:31 | access to parameter s |
 | Guards.cs:205:13:205:13 | access to parameter o |
 | Guards.cs:208:17:208:17 | access to parameter o |
+| Guards.cs:269:11:269:12 | access to parameter o1 |
 | Splitting.cs:13:17:13:17 | access to parameter o |
 | Splitting.cs:23:24:23:24 | access to parameter o |
 | Splitting.cs:35:13:35:13 | access to parameter o |