• Per =?UTF-8?B?Tm9yZGzDtnc=?= (10/10) Mar 02 2024 Why does disabling a struct's postblit increase its sizeof by one
• kinke (4/13) Mar 02 2024 Not according to run.dlang.io, for all available DMD versions.
• Per =?UTF-8?B?Tm9yZGzDtnc=?= (2/5) Mar 02 2024 Ahh. Yes. Indeed. My mistake. Thanks.
• Per =?UTF-8?B?Tm9yZGzDtnc=?= (3/8) Mar 02 2024 Thanks. Neither my websearches nor ChatGPT plus couldn't figure
• Paul Backus (24/33) Mar 03 2024 FYI, you can dump the layout of a struct, including hidden

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

Why does disabling a struct's postblit increase its sizeof by one 
word?

The following holds:

```d
struct S {  disable this(this); int _; }
struct T { int _; }
static assert(S.sizeof == 16);
static assert(T.sizeof == int.sizeof);
```

. Why is this needed?

kinke <noone nowhere.com> writes:

On Saturday, 2 March 2024 at 15:25:48 UTC, Per Nordlöw wrote:
 Why does disabling a struct's postblit increase its sizeof by 
 one word?

 The following holds:

 ```d
 struct S {  disable this(this); int _; }
 struct T { int _; }
 static assert(S.sizeof == 16);
 static assert(T.sizeof == int.sizeof);
 ```

Not according to run.dlang.io, for all available DMD versions. 
Perhaps your tested `S` was nested in some function/aggregate and 
so had an implicit context pointer.

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

On Saturday, 2 March 2024 at 19:11:42 UTC, kinke wrote:
 Not according to run.dlang.io, for all available DMD versions. 
 Perhaps your tested `S` was nested in some function/aggregate 
 and so had an implicit context pointer.

Ahh. Yes. Indeed. My mistake. Thanks.

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

On Saturday, 2 March 2024 at 19:28:08 UTC, Per Nordlöw wrote:
 On Saturday, 2 March 2024 at 19:11:42 UTC, kinke wrote:
 Not according to run.dlang.io, for all available DMD versions. 
 Perhaps your tested `S` was nested in some function/aggregate 
 and so had an implicit context pointer.

 Ahh. Yes. Indeed. My mistake. Thanks.

Thanks. Neither my websearches nor ChatGPT plus couldn't figure 
that out.

Paul Backus <snarwin gmail.com> writes:

On Saturday, 2 March 2024 at 19:29:47 UTC, Per Nordlöw wrote:
 On Saturday, 2 March 2024 at 19:28:08 UTC, Per Nordlöw wrote:
 On Saturday, 2 March 2024 at 19:11:42 UTC, kinke wrote:
 Not according to run.dlang.io, for all available DMD 
 versions. Perhaps your tested `S` was nested in some 
 function/aggregate and so had an implicit context pointer.

 Ahh. Yes. Indeed. My mistake. Thanks.

 Thanks. Neither my websearches nor ChatGPT plus couldn't figure 
 that out.

FYI, you can dump the layout of a struct, including hidden 
fields, by iterating over its `.tupleof` property:

```d
void main()
{
     struct S
     {
          disable this(this);
         int n;
     }

     static foreach (field; S.tupleof)
         pragma(msg,
             typeof(field).stringof, " ",
             __traits(identifier, field), " ",
             "at ", field.offsetof
         );
}
```

This example prints out

```
int n at 0LU
void* this at 8LU
```