From b85dda77daee7b0ce51585c1bb75523caa03aa4f Mon Sep 17 00:00:00 2001
From: Paul Fultz II <pfultz2@yahoo.com>
Date: Sun, 8 Apr 2018 01:13:44 -0500
Subject: [PATCH] Add a check for identical inner conditions (#1156)

---
 lib/checkcondition.cpp | 14 ++++++++++++++
 lib/checkcondition.h   |  3 +++
 test/testcondition.cpp | 10 ++++++++++
 3 files changed, 27 insertions(+)

diff --git a/lib/checkcondition.cpp b/lib/checkcondition.cpp
index d68ef40db..3d6a4ef02 100644
--- a/lib/checkcondition.cpp
+++ b/lib/checkcondition.cpp
@@ -585,6 +585,8 @@ void CheckCondition::multiCondition2()
                         } else if (isOppositeCond(false, _tokenizer->isCPP(), firstCondition, cond2, _settings->library, true)) {
                             if (!isAliased(vars))
                                 oppositeInnerConditionError(firstCondition, cond2);
+                        } else if(isSameExpression(_tokenizer->isCPP(), true, firstCondition, cond2, _settings->library, true)) {
+                            identicalInnerConditionError(firstCondition, cond2);
                         }
                     }
                 } else {
@@ -693,6 +695,18 @@ void CheckCondition::oppositeInnerConditionError(const Token *tok1, const Token*
     reportError(errorPath, Severity::warning, "oppositeInnerCondition", msg, CWE398, false);
 }
 
+void CheckCondition::identicalInnerConditionError(const Token *tok1, const Token* tok2)
+{
+    const std::string s1(tok1 ? tok1->expressionString() : "x");
+    const std::string s2(tok2 ? tok2->expressionString() : "x");
+    ErrorPath errorPath;
+    errorPath.push_back(ErrorPathItem(tok1, "outer condition: " + s1));
+    errorPath.push_back(ErrorPathItem(tok2, "identical inner condition: " + s2));
+    const std::string msg("Identical inner 'if' condition is always true.\n"
+                          "Identical inner 'if' condition is always true (outer condition is '" + s1 + "' and inner condition is '" + s2 + "').");
+    reportError(errorPath, Severity::warning, "identicalInnerCondition", msg, CWE398, false);
+}
+
 void CheckCondition::identicalConditionAfterEarlyExitError(const Token *cond1, const Token* cond2)
 {
     const std::string cond(cond1 ? cond1->expressionString() : "x");
diff --git a/lib/checkcondition.h b/lib/checkcondition.h
index e330d471f..d05c277ef 100644
--- a/lib/checkcondition.h
+++ b/lib/checkcondition.h
@@ -133,6 +133,8 @@ private:
 
     void oppositeInnerConditionError(const Token *tok1, const Token* tok2);
 
+    void identicalInnerConditionError(const Token *tok1, const Token* tok2);
+
     void identicalConditionAfterEarlyExitError(const Token *cond1, const Token *cond2);
 
     void incorrectLogicOperatorError(const Token *tok, const std::string &condition, bool always, bool inconclusive);
@@ -156,6 +158,7 @@ private:
         c.multiConditionError(nullptr,1);
         c.mismatchingBitAndError(nullptr, 0xf0, nullptr, 1);
         c.oppositeInnerConditionError(nullptr, nullptr);
+        c.identicalInnerConditionError(nullptr, nullptr);
         c.identicalConditionAfterEarlyExitError(nullptr, nullptr);
         c.incorrectLogicOperatorError(nullptr, "foo > 3 && foo < 4", true, false);
         c.redundantConditionError(nullptr, "If x > 11 the condition x > 10 is always true.", false);
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index 9bd2cf354..8229f4942 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -87,6 +87,8 @@ private:
         TEST_CASE(oppositeInnerConditionAnd);
         TEST_CASE(oppositeInnerConditionEmpty);
 
+        TEST_CASE(identicalInnerCondition);
+
         TEST_CASE(identicalConditionAfterEarlyExit);
 
         TEST_CASE(clarifyCondition1);     // if (a = b() < 0)
@@ -1876,6 +1878,14 @@ private:
         check("void f1(const std::string v[10]) { if(v[0].size() > 42) if(v[1].empty()) {}} ");
         ASSERT_EQUALS("", errout.str());
     }
+    
+    void identicalInnerCondition() {
+        check("void f1(int a, int b) { if(a==b) if(a==b) {}}");
+        ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:1]: (warning) Identical inner 'if' condition is always true.\n", errout.str());
+
+        check("void f2(int a, int b) { if(a!=b) if(a!=b) {}}");
+        ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:1]: (warning) Identical inner 'if' condition is always true.\n", errout.str());
+    }
 
     void identicalConditionAfterEarlyExit() {
         check("void f(int x) {\n"