Re: [edk2-devel] [Question] using Flexible Array Member in Structure.

["Michael D Kinney" <michael.d.kinney@intel.com>]

Yes.  Use of flexible array members is supported and encouraged.

There are challenges with existing structure definitions that declare
arrays of size [1] when a flexible array is really intended. Those 
were defined before flexible array members were supported by all the
compilers.  Converting these to a flexible array member would not be
a backwards compatible change.

Mike

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
> levi.yun
> Sent: Wednesday, April 3, 2024 2:27 AM
> To: devel@edk2.groups.io
> Cc: nd@arm.com; sami.mujawar@arm.com
> Subject: [edk2-devel] [Question] using Flexible Array Member in
> Structure.
> 
> Hello all!
> 
> while I see the code. I have one question related using Flexible Array
> Member.
> 
> For example)
> 
> ///
> /// Socket Type Data.
> ///
> typedef struct {
>    EFI_ACPI_6_4_PMTT_COMMON_MEMORY_DEVICE CommonMemoryDeviceHeader;
>    UINT16 SocketIdentifier;
>    UINT16 Reserved;
>    // EFI_ACPI_6_4_PMTT_COMMON_MEMORY_DEVICE MemoryDeviceStructure[];
> } EFI_ACPI_6_4_PMTT_SOCKET_TYPE_DATA;
> 
> In here, why MemoryDeviceStructure should remain with comments?
> 
> IIUC, edk2 coding style guide doesn't seem to prevent use of Flexible
> Array Member which is C99 standard.
> 
> And consider the compiler used to compile edk2 uses defaults standard
> above of C99 standard.
> 
> Couldn't I use the flexible array member like:
> 
> ///
> /// Socket Type Data.
> ///
> typedef struct {
>    EFI_ACPI_6_4_PMTT_COMMON_MEMORY_DEVICE CommonMemoryDeviceHeader;
>    UINT16 SocketIdentifier;
>    UINT16 Reserved;
>    EFI_ACPI_6_4_PMTT_COMMON_MEMORY_DEVICE  MemoryDeviceStructure[]
> }
> 
> Thanks!
> 
> 
> 
> 



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