From d5442280b10d99743786d8808e18eaaba231686b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <danielm77@spray.se>
Date: Tue, 1 May 2012 07:06:14 +0200
Subject: [PATCH] Fixed #3597 (Errors in evaluation of chained assignment
 operators)

---
 lib/checknullpointer.cpp | 19 ++++++++++++++++++-
 test/testnullpointer.cpp |  8 ++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
index 24e28915f..c8224b3bc 100644
--- a/lib/checknullpointer.cpp
+++ b/lib/checknullpointer.cpp
@@ -863,7 +863,24 @@ void CheckNullPointer::nullPointerByDeRefAndChec()
                     //           uncertain
                     bool unknown = _settings->inconclusive;
 
-                    if (Token::Match(tok1->tokAt(-2), "%varid% = %varid% .", varid)) {
+                    // reassign : is the pointer reassigned like this:
+                    //            tok = tok->next();
+                    bool reassign = false;
+                    if (Token::Match(tok1->previous(), "= %varid% .", varid)) {
+                        const Token *back = tok1->tokAt(-2);
+                        while (back) {
+                            if (back->varId() == varid) {
+                                reassign = true;
+                                break;
+                            }
+                            if (Token::Match(back, "[{};,(]")) {
+                                break;
+                            }
+                            back = back->previous();
+                        }
+                    }
+
+                    if (reassign) {
                         break;
                     } else if (Token::simpleMatch(tok1->tokAt(-2), "* )") &&
                                Token::Match(tok1->linkAt(-1)->tokAt(-2), "%varid% = (", tok1->varId())) {
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index 520a946af..41846aef8 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -653,6 +653,14 @@ private:
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("void foo(x *p)\n"
+              "{\n"
+              "    p = *p2 = p->next;\n"
+              "    if (!p)\n"
+              "        ;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         check("void foo(struct ABC *abc)\n"
               "{\n"
               "    abc = abc ? abc->next : 0;\n"