From 7388034eef7d9a04318618b8597f4f52d31ebd3e Mon Sep 17 00:00:00 2001
From: hjk <qtc-committer@nokia.com>
Date: Mon, 7 May 2012 13:15:48 +0200
Subject: [PATCH] debugger: recognize null references explicitly.

Change-Id: Ie315997363d9f591526ea8c122759f59d808fae5
Reviewed-by: hjk <qthjk@ovi.com>
---
 share/qtcreator/dumper/dumper.py              |  9 +++++++
 .../debugger/simple/simple_test_app.cpp       | 26 +++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/share/qtcreator/dumper/dumper.py b/share/qtcreator/dumper/dumper.py
index 9eb1b9dbd59..c5cc107fa4b 100644
--- a/share/qtcreator/dumper/dumper.py
+++ b/share/qtcreator/dumper/dumper.py
@@ -1408,6 +1408,15 @@ class Dumper:
         #warn("REAL VALUE: %s " % value)
 
         if type.code == ReferenceCode:
+            try:
+                # Try to recognize null references explicitly.
+                if long(value.address) == 0:
+                    self.putValue("<null reference>")
+                    self.putType(typeName)
+                    self.putNumChild(0)
+                    return
+            except:
+                pass
             try:
                 # FIXME: This throws "RuntimeError: Attempt to dereference a
                 # generic pointer." with MinGW's gcc 4.5 when it "identifies"
diff --git a/tests/manual/debugger/simple/simple_test_app.cpp b/tests/manual/debugger/simple/simple_test_app.cpp
index 155424967ac..2d633f469c7 100644
--- a/tests/manual/debugger/simple/simple_test_app.cpp
+++ b/tests/manual/debugger/simple/simple_test_app.cpp
@@ -2100,6 +2100,31 @@ namespace final {
         dummyStatement(&app);
     }
 
+    void testNullReferenceHelper(int &i, int &j)
+    {
+        i += 1;
+        j += 1;
+    }
+
+    void testNullReference()
+    {
+        int i = 21;
+        int *p = &i;
+        int *q = 0;
+        int &pp = *p;
+        int &qq = *q;
+        BREAK_HERE;
+        // Check i 21 int.
+        // CheckType p int.
+        // Check p 21 int.
+        // Check q 0x0 int *.
+        // Check qq <null reference> int.
+        // Continue.
+        return; // Uncomment.
+        testNullReferenceHelper(pp, qq);
+        dummyStatement(p, q, &i);
+    }
+
     void testFinal(QCoreApplication *app)
     {
         // This contains all "final" tests that do not allow proceeding
@@ -2108,6 +2133,7 @@ namespace final {
         // Continue.
         testQSettings();
         testNullPointerDeref();
+        testNullReference();
         testEndlessLoop();
         testEndlessRecursion();
         testUncaughtException();