[GSoC] Header Generation for C/C++

[Manu]

On Tue, Jul 30, 2019 at 8:10 AM Andrei Alexandrescu via Digitalmars-d
<digitalmars-d at puremagic.com> wrote:
>
> On 7/30/19 10:50 AM, Eduard Staniloiu wrote:
> > On Tuesday, 30 July 2019 at 14:43:01 UTC, Eduard Staniloiu wrote:
> >> On Monday, 29 July 2019 at 01:19:36 UTC, Manu wrote:
> >>> On Sun, Jul 28, 2019 at 5:20 PM Gregor Mückl via Digitalmars-d
> >>> <digitalmars-d at puremagic.com> wrote:
> >>>>
> >>>> On Monday, 22 July 2019 at 18:12:01 UTC, Manu wrote:
> >>>> > [...]
> >>>>
> >>>> That's a pretty neat hack!
> >>>>
> >>>> I'm just worried about two things:
> >>>> - it makes the generated code harder to read (not that big of a
> >>>> deal)
> >>>
> >>> Barely... and a generated header is not really for human consumption
> >>> either way.
> >>>
> >>>> - if you happen to include headers with conflicting D_ENUM* defines
> >>>> (e.g. a potential 3rd party D wrapper), you might get some nasty
> >>>> surprises :/
> >>>
> >>> C/C++ programmers now how to do macros and what to expect.
> >>
> >> So should we go ahead with generating code based on the `-extern-std`
> >> value or by using defines?
> >>
> >> After sleeping a bit on this, I prefer `-extern-std`.
> >
> > BTW, I went with `-extern-std` in the current implementation (on GH).
> >
> > Another question is how should `align(n)` be generated. See the
> > following two:
> >
> > 1) __attribute__((packed, aligned(n)))
> >
> > or
> >
> > 2) __attribute__((aligned(n)))
> >
> > Note the missing `packed` between 1) and 2)
> >
> > Currently (on GH) the entire generated output looks like this
> >
> > struct
> > #if defined(__GNUC__) || defined(__clang__)
> >      __attribute__((packed, aligned(8)))
> > #elif defined(_MSC_VER)
> >      __declspec(align(8))
> > #elif defined(__DMC__)
> >      #pragma pack(push, 8)
> > #endif
> > MyStruct
> > {
> >    /* fields */
> > }
> > #if defined(__DMC__)
> >      #pragma pack(pop)
> > #endif
> >
>
> Better yet:
>
> #if defined(__GNUC__) || defined(__clang__)
>      #define BEGIN_PACK(n) __attribute__((packed, aligned(n)))
> #elif defined(_MSC_VER)
>      #define BEGIN_PACK(n) __declspec(align(n))
> #elif defined(__DMC__)
>      #define BEGIN_PACK(n) #pragma pack(push, n)
> #endif
>
> #if defined(__DMC__)
>      #define END_PACK() #pragma pack(pop)
> #else
>      #define END_PACK()
> #endif

This is precisely what I was just about to propose ;)