I think the only difference may be that gdc possibly folds the call to exp().

Check the difference between what code gdc generates compared to how gcc processed it:  -fdump-tree-original  -fdump-tree-optimized

----
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';

On 14 Jan 2012 06:56, "Daniel Green" <venix1@gmail.com> wrote:
>
> I've been working on fixing GDC/MinGW's runtime support.  I ran across the following and was hoping to get a clarification on what DMD does differently than GDC.
>
> void testexp()
> {
>    printf("exp(3.0) = %Lg, %Lg\n", exp(3.0), E * E * E);
>    assert(equals(exp(3.0), E * E * E, 16));
> }
>
> Of interest is exp(3.0).  GDC matches exp(3.0) to double exp(double). This causes problems with printf due to %Lg wanting a real but only receiving a double.
>
> Looking at the D specification for overloading functions.
>    1. no match
>    2. match with implicit conversions
>    3. match with conversion to const
>    4. exact match
>
>
> The specification doesn't indicate what levels are better.  I would guess 4 is the best since an exact match should take precedence.
> However, that results in GDC matching exp(3.0) to double exp(double).
>
> How does DMD match exp(3.0)?
>
> Could it possibly be a typo?  For 32-bit this test passes because the printf doesn't segfault, it's only  noticeable with 64-bit since it segfaults.