From 887b40e08b591eaa017c5be668932927e533d47d Mon Sep 17 00:00:00 2001
From: Paul Fultz II <pfultz2@yahoo.com>
Date: Sat, 26 Sep 2020 03:31:40 -0500
Subject: [PATCH] Fix issue 9916: False positive: duplicateAssignExpression
 when it's checked if variables have initial value later (#2825)

---
 lib/checkother.cpp | 41 +++++++++++++++++++++++++++++++----------
 test/testother.cpp | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 10 deletions(-)

diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 3103bfee3..7d1046ccf 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -2050,19 +2050,40 @@ void CheckOther::checkDuplicateExpression()
                         isSameExpression(mTokenizer->isCPP(), true, tok->next(), nextAssign->next(), mSettings->library, true, false) &&
                         isSameExpression(mTokenizer->isCPP(), true, tok->astOperand2(), nextAssign->astOperand2(), mSettings->library, true, false) &&
                         tok->astOperand2()->expressionString() == nextAssign->astOperand2()->expressionString()) {
-                        bool assigned = false;
+                        bool differentDomain = false;
                         const Scope * varScope = var1->scope() ? var1->scope() : scope;
                         for (const Token *assignTok = Token::findsimplematch(var2, ";"); assignTok && assignTok != varScope->bodyEnd; assignTok = assignTok->next()) {
-                            if (Token::Match(assignTok, "%varid% = %var%", var1->varId()) && Token::Match(assignTok, "%var% = %varid%", var2->varId())) {
-                                assigned = true;
-                                break;
-                            }
-                            if (Token::Match(assignTok, "%varid% = %var%", var2->varId()) && Token::Match(assignTok, "%var% = %varid%", var1->varId())) {
-                                assigned = true;
-                                break;
-                            }
+                            if (!Token::Match(assignTok, "%assign%|%comp%"))
+                                continue;
+                            if (!assignTok->astOperand1())
+                                continue;
+                            if (!assignTok->astOperand2())
+                                continue;
+
+                            if (assignTok->astOperand1()->varId() != var1->varId() &&
+                                assignTok->astOperand1()->varId() != var2->varId() &&
+                                !isSameExpression(mTokenizer->isCPP(),
+                                                  true,
+                                                  tok->astOperand2(),
+                                                  assignTok->astOperand1(),
+                                                  mSettings->library,
+                                                  true,
+                                                  true))
+                                continue;
+                            if (assignTok->astOperand2()->varId() != var1->varId() &&
+                                assignTok->astOperand2()->varId() != var2->varId() &&
+                                !isSameExpression(mTokenizer->isCPP(),
+                                                  true,
+                                                  tok->astOperand2(),
+                                                  assignTok->astOperand2(),
+                                                  mSettings->library,
+                                                  true,
+                                                  true))
+                                continue;
+                            differentDomain = true;
+                            break;
                         }
-                        if (!assigned && !isUniqueExpression(tok->astOperand2()))
+                        if (!differentDomain && !isUniqueExpression(tok->astOperand2()))
                             duplicateAssignExpressionError(var1, var2, false);
                         else if (mSettings->inconclusive)
                             duplicateAssignExpressionError(var1, var2, true);
diff --git a/test/testother.cpp b/test/testother.cpp
index 40833c093..f85cca9d6 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -5694,6 +5694,42 @@ private:
               "}");
         ASSERT_EQUALS("[test.cpp:4] -> [test.cpp:3]: (style, inconclusive) Same expression used in consecutive assignments of 'i' and 'j'.\n", errout.str());
 
+        check("struct A { int x; int y; };"
+              "void use(int);\n"
+              "void test(A a) {\n"
+              "    int i = a.x;\n"
+              "    int j = a.x;\n"
+              "    use(j);\n"
+              "    if (i == j) {}\n"
+              "}");
+        ASSERT_EQUALS(
+            "[test.cpp:4] -> [test.cpp:3]: (style, inconclusive) Same expression used in consecutive assignments of 'i' and 'j'.\n",
+            errout.str());
+
+        check("struct A { int x; int y; };"
+              "void use(int);\n"
+              "void test(A a) {\n"
+              "    int i = a.x;\n"
+              "    int j = a.x;\n"
+              "    use(j);\n"
+              "    if (i == a.x) {}\n"
+              "}");
+        ASSERT_EQUALS(
+            "[test.cpp:4] -> [test.cpp:3]: (style, inconclusive) Same expression used in consecutive assignments of 'i' and 'j'.\n",
+            errout.str());
+
+        check("struct A { int x; int y; };"
+              "void use(int);\n"
+              "void test(A a) {\n"
+              "    int i = a.x;\n"
+              "    int j = a.x;\n"
+              "    use(i);\n"
+              "    if (j == a.x) {}\n"
+              "}");
+        ASSERT_EQUALS(
+            "[test.cpp:4] -> [test.cpp:3]: (style, inconclusive) Same expression used in consecutive assignments of 'i' and 'j'.\n",
+            errout.str());
+
         // Issue #8612
         check("struct P\n"
               "{\n"