From 8812f2651713fe4832ee9cbb87e4d130fa4adca7 Mon Sep 17 00:00:00 2001
From: Tom Hvitved <tom@semmle.com>
Date: Wed, 6 Feb 2019 13:17:47 +0100
Subject: [PATCH] C#: Address review comments

---
 csharp/ql/src/Useless code/DefaultToString.ql         | 2 +-
 csharp/ql/src/semmle/code/csharp/ExprOrStmtParent.qll | 2 +-
 csharp/ql/src/semmle/code/csharp/Location.qll         | 3 +++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/csharp/ql/src/Useless code/DefaultToString.ql b/csharp/ql/src/Useless code/DefaultToString.ql
index 4bf9e3d92ec..656baac410c 100644
--- a/csharp/ql/src/Useless code/DefaultToString.ql	
+++ b/csharp/ql/src/Useless code/DefaultToString.ql	
@@ -72,7 +72,7 @@ class DefaultToStringType extends ValueOrRefType {
     result instanceof SourceLocation
     or
     not super.getLocation() instanceof SourceLocation and
-    result.hasLocationInfo("", 0, 0, 0, 0)
+    result instanceof EmptyLocation
   }
 }
 
diff --git a/csharp/ql/src/semmle/code/csharp/ExprOrStmtParent.qll b/csharp/ql/src/semmle/code/csharp/ExprOrStmtParent.qll
index 361e08d0975..602a2cadbb6 100644
--- a/csharp/ql/src/semmle/code/csharp/ExprOrStmtParent.qll
+++ b/csharp/ql/src/semmle/code/csharp/ExprOrStmtParent.qll
@@ -372,7 +372,7 @@ module ExprOrStmtParentCached {
     result = min(Location l | l = e.getALocation() | l order by l.getFile().toString())
     or
     not exists(e.getALocation()) and
-    result.hasLocationInfo("", 0, 0, 0, 0)
+    result instanceof EmptyLocation
   }
 }
 private import ExprOrStmtParentCached
diff --git a/csharp/ql/src/semmle/code/csharp/Location.qll b/csharp/ql/src/semmle/code/csharp/Location.qll
index 220a92bfa83..c217e51a432 100644
--- a/csharp/ql/src/semmle/code/csharp/Location.qll
+++ b/csharp/ql/src/semmle/code/csharp/Location.qll
@@ -51,6 +51,9 @@ class Location extends @location {
   final int getEndColumn() { this.hasLocationInfo(_, _, _, _, result) }
 }
 
+/** An empty location. */
+class EmptyLocation extends Location { EmptyLocation() { this.hasLocationInfo("", 0, 0, 0, 0) } }
+
 /**
  * A location in source code, comprising of a source file and a segment of text
  * within the file.