From 1c84dc814c0b398e1e0e7f55c5590d8332998eac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <danielm77@spray.se>
Date: Wed, 27 Jan 2010 19:16:32 +0100
Subject: [PATCH] Auto variables: Improved handling of temporaries

---
 lib/checkautovariables.cpp | 34 ++++++++++++++++++++++++++++++++++
 lib/checkautovariables.h   | 13 +++++++++++--
 test/testautovariables.cpp |  6 ++----
 3 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/lib/checkautovariables.cpp b/lib/checkautovariables.cpp
index 110c32e80..fc27070a5 100644
--- a/lib/checkautovariables.cpp
+++ b/lib/checkautovariables.cpp
@@ -307,6 +307,16 @@ void CheckAutoVariables::errorAutoVariableAssignment(const Token *tok)
 }
 
 
+
+// return temporary?
+bool CheckAutoVariables::returnTemporary(const Token *tok) const
+{
+    if (!Token::Match(tok, "return %var% ("))
+        return false;
+    return bool(0 != Token::findmatch(_tokenizer->tokens(), ("std :: string " + tok->next()->str() + " (").c_str()));
+}
+
+
 void CheckAutoVariables::returnReference()
 {
     // locate function that returns a reference..
@@ -381,6 +391,13 @@ void CheckAutoVariables::returnReference()
                             errorReturnReference(tok2);
                         }
                     }
+
+                    // return reference to temporary..
+                    else if (returnTemporary(tok2))
+                    {
+                        // report error..
+                        errorReturnTempReference(tok2);
+                    }
                 }
             }
         }
@@ -392,6 +409,11 @@ void CheckAutoVariables::errorReturnReference(const Token *tok)
     reportError(tok, Severity::error, "returnReference", "Returning reference to auto variable");
 }
 
+void CheckAutoVariables::errorReturnTempReference(const Token *tok)
+{
+    reportError(tok, Severity::error, "returnTempReference", "Returning reference to temporary");
+}
+
 
 // Return c_str
 void CheckAutoVariables::returncstr()
@@ -465,6 +487,13 @@ void CheckAutoVariables::returncstr()
                             errorReturnAutocstr(tok2);
                         }
                     }
+
+                    // return pointer to temporary..
+                    else if (returnTemporary(tok2))
+                    {
+                        // report error..
+                        errorReturnTempPointer(tok2);
+                    }
                 }
             }
         }
@@ -476,5 +505,10 @@ void CheckAutoVariables::errorReturnAutocstr(const Token *tok)
     reportError(tok, Severity::error, "returnAutocstr", "Returning pointer to auto variable");
 }
 
+void CheckAutoVariables::errorReturnTempPointer(const Token *tok)
+{
+    reportError(tok, Severity::error, "returnTempPointer", "Returning pointer to temporary");
+}
+
 
 
diff --git a/lib/checkautovariables.h b/lib/checkautovariables.h
index c63cfdf93..e6baa9102 100644
--- a/lib/checkautovariables.h
+++ b/lib/checkautovariables.h
@@ -72,19 +72,28 @@ private:
     void addVD(unsigned int varId);
     void addVDA(unsigned int varId);
 
-
+    /**
+     * Returning a temporary object?
+     * @param tok pointing at the "return" token
+     * @return true if a temporary object is returned
+     */
+    bool returnTemporary(const Token *tok) const;
 
     void errorReturnPointerToLocalArray(const Token *tok);
     void errorAutoVariableAssignment(const Token *tok);
     void errorReturnReference(const Token *tok);
+    void errorReturnTempReference(const Token *tok);
     void errorReturnAutocstr(const Token *tok);
+    void errorReturnTempPointer(const Token *tok);
 
     void getErrorMessages()
     {
         errorAutoVariableAssignment(0);
         errorReturnPointerToLocalArray(0);
         errorReturnReference(0);
+        errorReturnTempReference(0);
         errorReturnAutocstr(0);
+        errorReturnTempPointer(0);
     }
 
     std::string name() const
@@ -96,7 +105,7 @@ private:
     {
         return "A pointer to a variable is only valid as long as the variable is in scope.\n"
                "Check:\n"
-               "* returning a pointer to auto variable\n"
+               "* returning a pointer to auto or temporary variable\n"
                "* assigning address of an variable to an effective parameter of a function\n"
                "* returning reference to local/temporary variable\n";
     }
diff --git a/test/testautovariables.cpp b/test/testautovariables.cpp
index f402eadc6..ad34a641d 100644
--- a/test/testautovariables.cpp
+++ b/test/testautovariables.cpp
@@ -201,8 +201,7 @@ private:
               "{\n"
               "    return hello();\n"
               "}\n");
-        ASSERT_EQUALS("", errout.str());
-        TODO_ASSERT_EQUALS("[test.cpp:5]: (error) Returning reference to temporary\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:8]: (error) Returning reference to temporary\n", errout.str());
     }
 
     void returncstr()
@@ -223,8 +222,7 @@ private:
               "{\n"
               "    return hello().c_str();\n"
               "}\n");
-        ASSERT_EQUALS("", errout.str());
-        TODO_ASSERT_EQUALS("[test.cpp:5]: (error) Returning pointer to temporary\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:8]: (error) Returning pointer to temporary\n", errout.str());
     }
 
 };