Fix #11082 FN badBitmaskCheck for binary or with 0 (#4170)

* Fix #11082 FN badBitmaskCheck for binary or with 0

* Add test for #10703

lib/checkcondition.cpp

@@ -310,12 +310,21 @@ void CheckCondition::checkBadBitmaskCheck()
 
             if (isBoolean && isTrue)
                 badBitmaskCheckError(tok);
+
+            const bool isNoOp = (tok->astOperand1()->hasKnownIntValue() && tok->astOperand1()->values().front().intvalue == 0) ||
+                                (tok->astOperand2()->hasKnownIntValue() && tok->astOperand2()->values().front().intvalue == 0);
+
+            if (isNoOp)
+                badBitmaskCheckError(tok, isNoOp);
         }
     }
 }
 
-void CheckCondition::badBitmaskCheckError(const Token *tok)
+void CheckCondition::badBitmaskCheckError(const Token *tok, bool isNoOp)
 {
+    if (isNoOp)
+        reportError(tok, Severity::warning, "badBitmaskCheck", "Operator '|' with one operand equal to zero is redundant.", CWE571, Certainty::normal);
+    else
         reportError(tok, Severity::warning, "badBitmaskCheck", "Result of operator '|' is always true if one operand is non-zero. Did you intend to use '&'?", CWE571, Certainty::normal);
 }
 

lib/checkcondition.h

@@ -136,7 +136,7 @@ private:
     bool isOverlappingCond(const Token * const cond1, const Token * const cond2, bool pure) const;
     void assignIfError(const Token *tok1, const Token *tok2, const std::string &condition, bool result);
     void mismatchingBitAndError(const Token *tok1, const MathLib::bigint num1, const Token *tok2, const MathLib::bigint num2);
-    void badBitmaskCheckError(const Token *tok);
+    void badBitmaskCheckError(const Token *tok, bool isNoOp = false);
     void comparisonError(const Token *tok,
                          const std::string &bitop,
                          MathLib::bigint value1,

test/testcondition.cpp

@@ -887,6 +887,12 @@ private:
               "  }\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        check("void f(int i) {\n" // #11082
+              "    int j = 0;\n"
+              "    if (i | j) {}\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (warning) Operator '|' with one operand equal to zero is redundant.\n", errout.str());
     }
 
 

test/testunusedvar.cpp

@@ -5918,6 +5918,16 @@ private:
                               "    g();\n"
                               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("int f(int *p) {\n" // #10703
+                              "    std::unique_ptr<int> up(p);\n"
+                              "    return *p;\n"
+                              "}\n"
+                              "int g(int* p) {\n"
+                              "    auto up = std::unique_ptr<int>(p);\n"
+                              "    return *p;\n"
+                              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     // ticket #3104 - false positive when variable is read with "if (NOT var)"