From dd155b57e4222b13e2a4849dde3c046a0bf49d46 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Wed, 20 Mar 2013 06:38:53 +0100
Subject: [PATCH] Fixed #4487 (False positive: variable is not assigned a value
 (pointer alias))

---
 lib/checkunusedvar.cpp | 10 ++++++++++
 test/testunusedvar.cpp | 17 +++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
index 0844745f4..e429758f0 100644
--- a/lib/checkunusedvar.cpp
+++ b/lib/checkunusedvar.cpp
@@ -605,6 +605,16 @@ static const Token* doAssignment(Variables &variables, const Token *tok, bool de
         }
     }
 
+    // Possible pointer alias
+    else if (Token::Match(tok, "%var% = %var% ;")) {
+        const unsigned int varid2 = tok->tokAt(2)->varId();
+        Variables::VariableUsage *var2 = variables.find(varid2);
+        if (var2 && (var2->_type == Variables::array ||
+                     var2->_type == Variables::pointer)) {
+            variables.use(varid2,tok);
+        }
+    }
+
     return tok;
 }
 
diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
index f957c78e2..69114d4a2 100644
--- a/test/testunusedvar.cpp
+++ b/test/testunusedvar.cpp
@@ -104,6 +104,7 @@ private:
         TEST_CASE(localvaralias10); // ticket #2004
         TEST_CASE(localvaralias11); // ticket #4423 - iterator
         TEST_CASE(localvaralias12); // ticket #4394
+        TEST_CASE(localvaralias13); // ticket #4487
         TEST_CASE(localvarasm);
         TEST_CASE(localvarstatic);
         TEST_CASE(localvarextern);
@@ -2744,6 +2745,22 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void localvaralias13() { // #4487
+        functionVariableUsage("void f(char *p) {\n"
+                              "    char a[4];\n"
+                              "    p = a;\n"
+                              "    strcpy(p, \"x\");\n"
+                              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("void f(char *p) {\n"
+                              "    char a[4];\n"
+                              "    p = a;\n"
+                              "    strcpy(p, \"x\");\n"
+                              "}");
+        TODO_ASSERT_EQUALS("a is assigned value that is never used", "", errout.str());
+    }
+
     void localvarasm() {
         functionVariableUsage("void foo(int &b)\n"
                               "{\n"