On Fri, Jan 29, 2016 at 07:13:00PM +0100, Magnus Fromreide wrote:
> I just noticed that the C and C++ compiler output pointer types differently:
>
> Consider
>
> int i;
> printf("%p", &i);
>
> When compiled as C that gives the warning
>
> format '%p' expects argument of type 'void *', but argument 2 has type 'int *'
>
> but when compiled as C++ it gives the warning
>
> format '%p' expects argument of type 'void*', but argument 2 has type 'int*'
>
> Why are they different?
So, C and C++ have different printers (C has c_tree_printer and C++
cp_printer). But in this case the difference comes from format_type_warning:
2657 p = (char *) alloca (pointer_count + 2);
2658 if (pointer_count == 0)
2659 p[0] = 0;
2660 else if (c_dialect_cxx ())
2661 {
2662 memset (p, '*', pointer_count);
2663 p[pointer_count] = 0;
2664 }
2665 else
2666 {
2667 p[0] = ' ';
2668 memset (p + 1, '*', pointer_count);
2669 p[pointer_count + 1] = 0;
2670 }
So the C FE gets the space but the C++ FE does not. The reason for this is
probably to keep in sync with the C++ printer which doesn't put space before
'*'; in dump_type_prefix we have
741 if (TYPE_PTR_P (t))
742 pp_star (pp);
so there's no pp_cxx_whitespace before '*'.
I like the version with space more; maybe we could change this in the next
stage1.
Marek
