From 9465dca5833562008d4104f513eff048cc09a500 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Mon, 4 Sep 2017 09:34:03 +0200
Subject: [PATCH] CheckCondition: Fix FPs for aliased variables (daca)

---
 lib/checkcondition.cpp | 19 +++++++++++++++----
 lib/checkcondition.h   |  2 +-
 test/testcondition.cpp | 15 +++++++++++++++
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/lib/checkcondition.cpp b/lib/checkcondition.cpp
index 27999245a..f37a9c36b 100644
--- a/lib/checkcondition.cpp
+++ b/lib/checkcondition.cpp
@@ -51,6 +51,13 @@ namespace {
     CheckCondition instance;
 }
 
+bool CheckCondition::isAliased(const std::set<unsigned int> &vars) const {
+    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
+		if (Token::Match(tok, "= & %var% ;") && vars.find(tok->tokAt(2)->varId()) != vars.end())
+			return true;
+	}
+	return false;
+}
 
 void CheckCondition::assignIf()
 {
@@ -516,11 +523,15 @@ void CheckCondition::multiCondition2()
                 const Token *cond2 = tok->next()->astOperand2();
 
                 if (type == MULTICONDITIONTYPE::INNER) {
-                    if (isOppositeCond(false, _tokenizer->isCPP(), cond1, cond2, _settings->library, true))
-                        oppositeInnerConditionError(cond1, cond2);
+                    if (isOppositeCond(false, _tokenizer->isCPP(), cond1, cond2, _settings->library, true)) {
+						if (!isAliased(vars))
+							oppositeInnerConditionError(cond1, cond2);
+                    }
                 } else {
-                    if (isSameExpression(_tokenizer->isCPP(), true, cond1, cond2, _settings->library, true))
-                        sameConditionAfterEarlyExitError(cond1, cond2);
+                    if (isSameExpression(_tokenizer->isCPP(), true, cond1, cond2, _settings->library, true)) {
+                        if (!isAliased(vars))
+							sameConditionAfterEarlyExitError(cond1, cond2);
+					}
                 }
 
             }
diff --git a/lib/checkcondition.h b/lib/checkcondition.h
index cf8a135bc..ff077b4f6 100644
--- a/lib/checkcondition.h
+++ b/lib/checkcondition.h
@@ -114,7 +114,7 @@ public:
     void checkInvalidTestForOverflow();
 
 private:
-
+	bool isAliased(const std::set<unsigned int> &vars) const;
     bool isOverlappingCond(const Token * const cond1, const Token * const cond2, bool pure) const;
     void assignIfError(const Token *tok1, const Token *tok2, const std::string &condition, bool result);
     void mismatchingBitAndError(const Token *tok1, const MathLib::bigint num1, const Token *tok2, const MathLib::bigint num2);
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index 8cce0d1e6..ad94819cf 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -76,6 +76,7 @@ private:
         TEST_CASE(modulo);
 
         TEST_CASE(oppositeInnerCondition);
+        TEST_CASE(oppositeInnerConditionAlias);
         TEST_CASE(oppositeInnerCondition2);
         TEST_CASE(oppositeInnerConditionAnd);
 
@@ -1597,6 +1598,20 @@ private:
         ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Opposite inner 'if' condition leads to a dead code block.\n", errout.str());
     }
 
+    void oppositeInnerConditionAlias() {
+        check("void f() {\n"
+              "  struct S s;\n"
+              "  bool hasFailed = false;\n"
+              "  s.status = &hasFailed;\n"
+              "\n"
+              "  if (! hasFailed) {\n"
+              "    doStuff(&s);\n"
+              "    if (hasFailed) {}\n"
+              "  }\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void oppositeInnerCondition2() {
         // first comparison: <
         check("void f(int x) {\n"