ghaerr commented on PR #19912:
URL: https://github.com/apache/nuttx/pull/19912#issuecomment-5860582611
> I tried adding #pragma pack(2) to MWDLGTEMPLATE on my machine, but it does
not work. It looks like the reason is that the members of MWDLGTEMPLATE carry
the PACKEDDATA macro (__attribute__((packed)) on each member), which removes
the alignment requirement entirely.
It seems the structures are identical except that MWDLGTEMPLATE uses a
non-packed 'char extradata[1]` member, which I am guessing perhaps tells your
compiler the structure as a whole is 4-byte aligned. Perhaps adding PACKEDDATA
to that member declaration and possibly also to the structure itself may get
the compiler to think both structure pointers are 1-byte aligned, rather than
1- and 4-byte aligned; something like the following:
```
typedef struct tagMWDLGTEMPLATE
{
DWORD style;
DWORD dwExtendedStyle;
WORD PACKEDDATA cdit;
short PACKEDDATA x;
short PACKEDDATA y;
short PACKEDDATA cx;
short PACKEDDATA cy;
/* other information that follows, var length */
char PACKEDDATA extraData[1]; // <--- add PACKEDDATA here
} PACKEDDATA MWDLGTEMPLATE, *PMWDLGTEMPLATE; // <--- as well as here
```
> To move forward with NuttX, I suggest only to suppress warning for now.
Agreed this may be the best option to avoid introducing other potential
problems. But rather than muddying Microwindows .c source files with \#ifdef
NUTTX statements just to remove a warning for your build, I suggest putting the
GCC \#pragma in the config.nuttx file instead, so the warning(s) will always be
suppressed.
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