fix #2786

lib/checkother.cpp

@@ -210,6 +210,16 @@ void CheckOther::checkFflushOnInputStream()
     }
 }
 
+void CheckOther::checkSizeofForNumericParameter()
+{
+    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
+    {
+        if (Token::Match(tok, "sizeof ( %num% )") || Token::Match(tok, "sizeof %num%"))
+        {
+            sizeofForNumericParameterError(tok);
+        }
+    }
+}
 
 void CheckOther::checkSizeofForArrayParameter()
 {
@@ -853,6 +863,19 @@ void CheckOther::checkComparisonOfBoolWithInt()
     }
 }
 
+void CheckOther::sizeofForNumericParameterError(const Token *tok)
+{
+    reportError(tok, Severity::error,
+                "sizeofwithnulericparamter", "Using sizeof with a numeric constant as function "
+                "argument might not be what you intended.\n"
+                "It is unusual to use contant value with sizeof. For example, this code:\n"
+                "     int f() {\n"
+                "         return sizeof(10);\n"
+                "     }\n"
+                " returns 4 (in 32-bit systems) or 8 (in 64-bit systems) instead of 10."
+               );
+}
+
 void CheckOther::sizeofForArrayParameterError(const Token *tok)
 {
     reportError(tok, Severity::error,
@@ -869,6 +892,7 @@ void CheckOther::sizeofForArrayParameterError(const Token *tok)
                 "size of the array in bytes)."
                );
 }
+
 void CheckOther::invalidScanfError(const Token *tok)
 {
     reportError(tok, Severity::warning,

lib/checkother.h

@@ -62,6 +62,7 @@ public:
         checkOther.checkRedundantAssignmentInSwitch();
         checkOther.checkAssignmentInAssert();
         checkOther.checkSizeofForArrayParameter();
+        checkOther.checkSizeofForNumericParameter();
         checkOther.checkSelfAssignment();
         checkOther.checkDuplicateIf();
         checkOther.checkDuplicateBranch();
@@ -199,6 +200,9 @@ public:
     /** @brief %Check for using sizeof with array given as function argument */
     void checkSizeofForArrayParameter();
 
+    /** @brief %Check for using sizeof with numeric given as function argument */
+    void checkSizeofForNumericParameter();
+
     /** @brief %Check for using bad usage of strncmp and substr */
     void checkIncorrectStringCompare();
 
@@ -245,6 +249,7 @@ public:
     void catchExceptionByValueError(const Token *tok);
     void memsetZeroBytesError(const Token *tok, const std::string &varname);
     void sizeofForArrayParameterError(const Token *tok);
+    void sizeofForNumericParameterError(const Token *tok);
     void incorrectStringCompareError(const Token *tok, const std::string& func, const std::string &string, const std::string &len);
     void incrementBooleanError(const Token *tok);
     void comparisonOfBoolWithIntError(const Token *tok, const std::string &varname);
@@ -265,6 +270,7 @@ public:
         c.fflushOnInputStreamError(0, "stdin");
         c.misusedScopeObjectError(NULL, "varname");
         c.sizeofForArrayParameterError(0);
+        c.sizeofForNumericParameterError(0);
 
         // style/warning
         c.cstyleCastError(0);
@@ -318,6 +324,7 @@ public:
                "* scoped object destroyed immediately after construction\n"
                "* assignment in an assert statement\n"
                "* sizeof for array given as function argument\n"
+               "* sizeof for numeric given as function argument\n"
                "* incorrect length arguments for 'substr' and 'strncmp'\n"
 
                // style

test/testother.cpp

@@ -104,6 +104,7 @@ private:
         TEST_CASE(memsetZeroBytes);
 
         TEST_CASE(sizeofForArrayParameter);
+        TEST_CASE(sizeofForNumericParameter);
 
         TEST_CASE(clarifyCalculation);
 
@@ -143,6 +144,7 @@ private:
         checkOther.checkRedundantAssignmentInSwitch();
         checkOther.checkAssignmentInAssert();
         checkOther.checkSizeofForArrayParameter();
+        checkOther.checkSizeofForNumericParameter();
         checkOther.clarifyCondition();
         checkOther.checkDuplicateIf();
         checkOther.checkDuplicateBranch();
@@ -2301,7 +2303,21 @@ private:
              );
         ASSERT_EQUALS("", errout.str());
 
+    }
 
+    void sizeofForNumericParameter()
+    {
+        check("void f() {\n"
+              "    std::cout << sizeof(10) << std::endl;\n"
+              "}\n"
+             );
+        ASSERT_EQUALS("[test.cpp:2]: (error) Using sizeof with a numeric constant as function argument might not be what you intended.\n", errout.str());
+
+        check("void f() {\n"
+              "    std::cout << sizeof 10  << std::endl;\n"
+              "}\n"
+             );
+        ASSERT_EQUALS("[test.cpp:2]: (error) Using sizeof with a numeric constant as function argument might not be what you intended.\n", errout.str());
 
     }