From a2febc49d6c3bfd7546038091538810742671309 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Thu, 15 Nov 2012 08:36:43 +0100
Subject: [PATCH] Fixed #4318 (False positive: 'unreadVariable')

---
 lib/checkunusedvar.cpp | 11 ++++++-----
 test/testunusedvar.cpp |  6 ++++++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
index 68ad423fb..3e307cbca 100644
--- a/lib/checkunusedvar.cpp
+++ b/lib/checkunusedvar.cpp
@@ -735,9 +735,8 @@ void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const
             variables.use(tok->tokAt(2)->varId(), tok);
         }
         // assignment
-        else if (!Token::Match(tok->tokAt(-2), "[;{}.] %var% (") &&
-                 (Token::Match(tok, "*| ++|--| %var% ++|--| =") ||
-                  Token::Match(tok, "*| ( const| %type% *| ) %var% ="))) {
+        else if (Token::Match(tok, "*| ++|--| %var% ++|--| =") ||
+                 Token::Match(tok, "*| ( const| %type% *| ) %var% =")) {
             bool dereference = false;
             bool pre = false;
             bool post = false;
@@ -762,7 +761,7 @@ void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const
                 post = true;
 
             const unsigned int varid1 = tok->varId();
-            const Token *start = tok;
+            const Token * const start = tok;
 
             tok = doAssignment(variables, tok, dereference, scope);
 
@@ -777,7 +776,9 @@ void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const
                 variables.read(varid1, tok);
             } else {
                 Variables::VariableUsage *var = variables.find(varid1);
-                if (var && var->_type == Variables::reference) {
+                if (var && Token::simpleMatch(start->previous(), ",")) {
+                    variables.use(varid1, tok);
+                } else if (var && var->_type == Variables::reference) {
                     variables.writeAliases(varid1, tok);
                     variables.read(varid1, tok);
                 }
diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
index 6ce2a7fcc..4910b0799 100644
--- a/test/testunusedvar.cpp
+++ b/test/testunusedvar.cpp
@@ -1494,6 +1494,12 @@ private:
                               "    return a + b;\n"
                               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("int f() {\n" // ticket #4318
+                              "    int a,b;\n"
+                              "    x(a, b=2);\n"  // <- if param2 is passed-by-reference then b might be used in x
+                              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void localvar37() { // ticket #3078