New check: look for calculation inside sizeof

lib/checkother.cpp

@@ -4134,6 +4134,41 @@ void CheckOther::sizeofsizeofError(const Token *tok)
                 "sizeofsizeof", "Suspicious code 'sizeof sizeof ..', most likely there should only be one sizeof. The current code is equivalent to 'sizeof(size_t)'.");
 }
 
+void CheckOther::sizeofCalculation()
+{
+    if (!_settings->_checkCodingStyle)
+        return;
+    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
+    {
+        if (Token::simpleMatch(tok, "sizeof ("))
+        {
+            unsigned int parlevel = 0;
+            for (const Token *tok2 = tok->tokAt(2); tok2; tok2 = tok2->next())
+            {
+                if (tok2->str() == "(")
+                    ++parlevel;
+                else if (tok2->str() == ")")
+                {
+                    if (parlevel <= 1)
+                        break;
+                    --parlevel;
+                }
+                else if (Token::Match(tok2, "+|/"))
+                {
+                    sizeofCalculationError(tok2);
+                    break;
+                }
+            }
+        }
+    }
+}
+
+void CheckOther::sizeofCalculationError(const Token *tok)
+{
+    reportError(tok, Severity::style,
+                "sizeofCalculation", "Found calculation inside sizeof()");
+}
+
 void CheckOther::redundantAssignmentInSwitchError(const Token *tok, const std::string &varname)
 {
     reportError(tok, Severity::style,

lib/checkother.h

@@ -61,6 +61,7 @@ public:
         checkOther.checkStructMemberUsage();
         checkOther.strPlusChar();
         checkOther.sizeofsizeof();
+        checkOther.sizeofCalculation();
         checkOther.checkEmptyCatchBlock();
         checkOther.checkRedundantAssignmentInSwitch();
     }
@@ -179,6 +180,10 @@ public:
     void sizeofsizeof();
     void sizeofsizeofError(const Token *tok);
 
+    /** @brief %Check for calculations inside sizeof */
+    void sizeofCalculation();
+    void sizeofCalculationError(const Token *tok);
+
     /** @brief %Check for assigning to the same variable twice in a switch statement*/
     void checkRedundantAssignmentInSwitch();
 
@@ -238,6 +243,7 @@ public:
         conditionAlwaysTrueFalse(0, "true/false");
         strPlusChar(0);
         sizeofsizeofError(0);
+        sizeofCalculationError(0);
         emptyCatchBlockError(0);
         redundantAssignmentInSwitchError(0, "varname");
 
@@ -276,6 +282,8 @@ public:
                "* unusal pointer arithmetic. For example: \"abc\" + 'd'\n"
                "* empty catch() block\n"
                "* redundant assignment in a switch statement\n"
+               "* look for 'sizeof sizeof ..'\n"
+               "* look for calculations inside sizeof()\n"
 
                // optimisations
                "* optimisation: detect post increment/decrement\n"

test/testother.cpp

@@ -98,6 +98,7 @@ private:
         TEST_CASE(fflushOnInputStreamTest);
 
         TEST_CASE(sizeofsizeof);
+        TEST_CASE(sizeofCalculation);
 
         TEST_CASE(emptyCatchBlock);
 
@@ -120,6 +121,7 @@ private:
         errout.str("");
 
         checkOther.sizeofsizeof();
+        checkOther.sizeofCalculation();
         checkOther.checkEmptyCatchBlock();
         checkOther.checkRedundantAssignmentInSwitch();
 
@@ -2783,6 +2785,12 @@ private:
         ASSERT_EQUALS("[test.cpp:3]: (style) Suspicious code 'sizeof sizeof ..', most likely there should only be one sizeof. The current code is equivalent to 'sizeof(size_t)'.\n", errout.str());
     }
 
+    void sizeofCalculation()
+    {
+        check("sizeof(a+b)");
+        ASSERT_EQUALS("[test.cpp:1]: (style) Found calculation inside sizeof()\n", errout.str());
+    }
+
     void emptyCatchBlock()
     {
         check("void Open(String name)\n"