SA0021: Transporting the address of a temporary variable

Detects address assignments of temporary variables (on the stack) to non-temporary variables

Justification: Local variables of a function or method are created on the stack and they exist only while the function or method is being processed. If a pointer points to this kind of variable after processing the method or function, then you can use this pointer to access undefined memory, or to access an incorrect variable in another function. This situation should be avoided at all costs.

Importance: High

FUNCTION TempVarInFUNC : DWORD
VAR
    uiTemp : UINT;
END_VAR

TempVarInFUNC := ADR(uiTemp);    //SA0021

PROGRAM PLC_PRG
VAR
    dwTest : DWORD;
END_VAR

dwTest := TempVarInFUNC();