From 67e40a85e5fbe01aac206e55b7349a0d7899c8c7 Mon Sep 17 00:00:00 2001
From: Arpit Chaudhary <arpchaudhary@paypal.com>
Date: Tue, 4 Sep 2012 16:06:00 +0530
Subject: [PATCH] Improved check for shifting by negative values and removed
 false positives

---
 lib/checkother.cpp | 14 +++++++++++---
 test/testother.cpp | 20 ++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 9928e779f..a809e76be 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -3329,10 +3329,18 @@ void CheckOther::redundantCopyError(const Token *tok,const std::string& varname)
 
 void CheckOther::checkNegativeBitwiseShift()
 {
+    const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
+
     for (const Token *tok = _tokenizer->tokens(); tok ; tok = tok->next()) {
-        if (Token::Match(tok,"%var% >>|<< %num%") || Token::Match(tok,"%num >>|<< %num%")) {
-            if ((tok->strAt(2))[0] == '-')
-                negativeBitwiseShiftError(tok);
+        if ((Token::Match(tok,"%var% >>|<< %num%") || Token::Match(tok,"%num% >>|<< %num%")) && !Token::Match(tok->previous(),">>|<<")) {
+            if (tok->isName()) {
+                const Variable* var = symbolDatabase->getVariableFromVarId(tok->varId());
+                if (var && var->typeStartToken()->isStandardType() && (tok->strAt(2))[0] == '-')
+                    negativeBitwiseShiftError(tok);
+            } else {
+                if ((tok->strAt(2))[0] == '-')
+                    negativeBitwiseShiftError(tok);
+            }
         }
     }
 }
diff --git a/test/testother.cpp b/test/testother.cpp
index 61982eb1e..82a9520ca 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -6111,6 +6111,26 @@ private:
               "   a >>= -1;\n"
               "}");
         ASSERT_EQUALS("[test.cpp:4]: (error) Shifting by a negative value.\n", errout.str());
+        check("void foo()\n"
+              "{\n"
+              "   int a = 123 << -1;\n"
+              "}");
+        TODO_ASSERT_EQUALS("[test.cpp:3]: (error) Shifting by a negative value.\n", "", errout.str());
+        check("void foo()\n"
+              "{\n"
+              "   std::cout << -1;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+        check("void foo()\n"
+              "{\n"
+              "   std::cout << a << -1 ;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+        check("void foo()\n"
+              "{\n"
+              "   std::cout << 3 << -1 ;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void incompleteArrayFill() {