Fixed cppcheck-opensource#6168 (False positive: sign conversion for inner calculation)

danmar · danmar · commit d354cdc02cf1 · 2014-09-14T10:29:58.000+02:00
diff --git a/lib/checktype.cpp b/lib/checktype.cpp
@@ -238,7 +238,8 @@ void CheckType::checkSignConversion()
 
             // Check if there are signed operands that can be negative..
             std::stack<const Token *> tokens;
-            tokens.push(tok);
+            tokens.push(tok->astOperand1());
+            tokens.push(tok->astOperand2());
             while (!tokens.empty()) {
                 const Token *tok1 = tokens.top();
                 tokens.pop();
@@ -268,8 +269,6 @@ void CheckType::checkSignConversion()
                         break;
                     }
                 }
-                tokens.push(tok1->astOperand1());
-                tokens.push(tok1->astOperand2());
             }
         }
     }
diff --git a/test/testtype.cpp b/test/testtype.cpp
@@ -117,6 +117,12 @@ class TestType : public TestFixture {
               "void f2() { f1(-4); }");
         ASSERT_EQUALS("[test.cpp:1]: (warning) Suspicious code: sign conversion of x in calculation, even though x can have a negative value\n", errout.str());
 
+        check("unsigned int f1(int x) {" // #6168: FP for inner calculation
+              "  return 5U * (1234 - x);\n" // <- signed subtraction, x is not sign converted
+              "}\n"
+              "void f2() { f1(-4); }");
+        ASSERT_EQUALS("", errout.str());
+
         // Dont warn for + and -
         check("void f1(int x) {"
               "  a = x + 5U;\n"

Original file line number	Diff line number	Diff line change
`@@ -238,7 +238,8 @@ void CheckType::checkSignConversion()`
`238`	`238`
`239`	`239`	`// Check if there are signed operands that can be negative..`
`240`	`240`	`std::stack<const Token *> tokens;`
`241`		`- tokens.push(tok);`
	`241`	`+ tokens.push(tok->astOperand1());`
	`242`	`+ tokens.push(tok->astOperand2());`
`242`	`243`	`while (!tokens.empty()) {`
`243`	`244`	`const Token *tok1 = tokens.top();`
`244`	`245`	`tokens.pop();`
`@@ -268,8 +269,6 @@ void CheckType::checkSignConversion()`
`268`	`269`	`break;`
`269`	`270`	`}`
`270`	`271`	`}`
`271`		`- tokens.push(tok1->astOperand1());`
`272`		`- tokens.push(tok1->astOperand2());`
`273`	`272`	`}`
`274`	`273`	`}`
`275`	`274`	`}`