Fix FP with complex array size expression (#4225)

* Partial fix for #11137 FN: invalidFunctionArgStr printf argument

* Typo

* Remove <strz>, suppressions

* Add suppresion, remove <strz>

* Add suppressions

* Fix FP with complex array size expression

Author: chrchr-github

lib/checkfunctions.cpp

@@ -144,9 +144,9 @@ void CheckFunctions::invalidFunctionUsage()
                         && valueType && (valueType->type == ValueType::Type::CHAR || valueType->type == ValueType::Type::WCHAR_T)) {
                         const Token* varTok = variable->declEndToken();
                         auto count = -1; // Find out explicitly set count, e.g.: char buf[3] = {...}. Variable 'count' is set to 3 then.
-                        if (varTok && Token::simpleMatch(varTok->previous(), "]"))
+                        if (varTok && Token::simpleMatch(varTok->astOperand1(), "["))
                         {
-                            const Token* const countTok = varTok->tokAt(-2);
+                            const Token* const countTok = varTok->astOperand1()->astOperand2();
                             if (countTok && countTok->hasKnownIntValue())
                                 count = countTok->getKnownIntValue();
                         }

test/testfunctions.cpp

@@ -723,6 +723,12 @@ class TestFunctions : public TestFixture {
               "    return wcslen(c);\n"
               "}\n");
         ASSERT_EQUALS("[test.cpp:3]: (error) Invalid wcslen() argument nr 1. A nul-terminated string is required.\n", errout.str());
+
+        check("void f(char* dest) {\n"
+              "    char if_name[(IF_NAMESIZE > 21 ? IF_NAMESIZE : 21) + 1] = \"%\";\n"
+              "    strcat(dest, if_name);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void mathfunctionCall_sqrt() {