From 739b6a93e244aa1d27366cc5dfba1a2ce262ae6a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <danielm77@spray.se>
Date: Sat, 16 Apr 2011 12:07:56 +0200
Subject: [PATCH] Fixed #2713 (False positive (Redundant assignment))

---
 lib/tokenize.cpp            | 16 ++++++++++++++++
 lib/tokenize.h              |  3 ++-
 test/testother.cpp          | 12 ++++++++++++
 test/testsimplifytokens.cpp | 19 +++++++++++++++----
 4 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 6eeaef283..1406816d5 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -6213,6 +6213,22 @@ void Tokenizer::simplifyIfNotNull()
     {
         Token *deleteFrom = NULL;
 
+        // Remove 'x = (x != 0)'
+        if (Token::simpleMatch(tok, "= ("))
+        {
+            if (Token::Match(tok->tokAt(-2), "[;{}] %var%"))
+            {
+                const unsigned int varid = tok->previous()->varId();
+                if (Token::Match(tok, "= ( %varid% != 0 ) ;", varid) ||
+                    Token::Match(tok, "= ( 0 != %varid% ) ;", varid))
+                {
+                    tok = tok->tokAt(-2);
+                    Token::eraseTokens(tok, tok->tokAt(9));
+                }
+            }
+            continue;
+        }
+
         if (Token::Match(tok, "(|&&|%oror%"))
         {
             tok = tok->next();
diff --git a/lib/tokenize.h b/lib/tokenize.h
index fb1eefc20..1a1377325 100644
--- a/lib/tokenize.h
+++ b/lib/tokenize.h
@@ -253,7 +253,8 @@ public:
 
     /**
      * simplify if-not NULL
-     * - "if(0!=x);" => "if(x);"
+     * Example: "if(0!=x);" => "if(x);"
+     * Special case: 'x = (0 != x);' is removed.
      */
     void simplifyIfNotNull();
 
diff --git a/test/testother.cpp b/test/testother.cpp
index e65f6a025..2fd0006c1 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -1582,6 +1582,18 @@ private:
               "        Fred fred; fred = fred;\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("void f(int x) {\n"
+              "    x = (x == 0);"
+              "    func(x);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void f(int x) {\n"
+              "    x = (x != 0);"
+              "    func(x);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void testScanf1()
diff --git a/test/testsimplifytokens.cpp b/test/testsimplifytokens.cpp
index 345354679..05419b35c 100644
--- a/test/testsimplifytokens.cpp
+++ b/test/testsimplifytokens.cpp
@@ -6727,11 +6727,22 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
-    void simplifyIfNotNull() // ticket # 2601 segmentation fault
+    void simplifyIfNotNull()
     {
-        const char code[] = "|| #if #define <=";
-        tok(code, false);
-        ASSERT_EQUALS("", errout.str());
+        {
+            // ticket # 2601 segmentation fault
+            const char code[] = "|| #if #define <=";
+            tok(code, false);
+            ASSERT_EQUALS("", errout.str());
+        }
+
+        {
+            const char code[] = "void f(int x) {\n"
+                                "    x = (x != 0);\n"
+                                "}";
+            ASSERT_EQUALS("void f ( int x ) { }", tok(code, false));
+        }
+
     }
 };