Detects unpacked structures that are used in packed structures
Justification: The compiler typically sets an unpacked structure to an address that allows aligned access to all elements within the structure. If you create this structure in a packed structure, then aligned access is no longer possible. Furthermore, access to an element in the unpacked structure can lead to a misalignment exception.
Importance: High
Example
The structure structSingleDataRecord is packed, but it contains the unpacked structures struct4Byte and struct9Byte.
{attribute 'pack_mode' := '1'}
TYPE structSingleDataRecord :
STRUCT
str9ByteData: struct9Byte; (* 9 BYTE *)
str4ByteData: struct4Byte; (* 4 BYTE *)
udi1: UDINT;
udi2: UDINT;
udi3: UDINT;
usi4: USINT;
END_STRUCT
END_TYPE (* 9 BYTE *)
TYPE struct9Byte :
STRUCT
usiRotorSlots: USINT; (* 1 BYTE *)
uiMaxCurrent: UINT; (* 2 BYTE *)
usiVelocity: USINT; (* 1 BYTE *)
uiAcceleration: UINT; (* 2 BYTE *)
uiDeceleration: UINT; (* 2 BYTE *)
usiDirectionChange: USINT; (* 1 BYTE *)
END_STRUCT
END_TYPE TYPE struct4Byte :
STRUCT
//udiDummy : UDINT;
rRealDummy : REAL;
END_STRUCT
END_TYPE
--> SA0161: Declaration of an unpacked struct 'struct9ByteData' inside a packed struct 'structSingleDataRecord'
--> SA0161: Declaration of an unpacked struct 'struct4ByteData' inside a packed struct 'structSingleDataRecord'