float f = float.min_normal;
    bool fcast1 = cast(bool)f;
    bool fcast2 = cast(bool)float.min_normal;

    if (fcast1)
        writeln("variable casting to bool is true");
    else
        writeln("variable casting to bool is false");

    if (fcast2)
        writeln("constant casting to bool is true");
    else
        writeln("constant casting to bool is false");

    if (float.min_normal)
        writeln("implicit conversion is true");
    else
        writeln("implicit conversion is false");


variable casting to bool is true
constant casting to bool is false
implicit conversion is true

Now, casting any float constant in the interval (-1.0;1.0) to bool will return false, but the same value considered as an if condition or variable will always return true;

Looking at disassembly, fcast2 is directly initialized to false, the compiler does not emit any conversion code:

bool fcast2 = cast(bool)float.min_normal;
004174fa  mov byte [ebp-0x3], 0x0

Is this intended behavior or it's a bug?

On 9 December 2017 at 12:51, rumbu via Digitalmars-d <digitalmars-d@puremagic.com> wrote:
>
>     float f = float.min_normal;
>     bool fcast1 = cast(bool)f;
>     bool fcast2 = cast(bool)float.min_normal;
>
>     if (fcast1)
>         writeln("variable casting to bool is true");
>     else
>         writeln("variable casting to bool is false");
>
>     if (fcast2)
>         writeln("constant casting to bool is true");
>     else
>         writeln("constant casting to bool is false");
>
>     if (float.min_normal)
>         writeln("implicit conversion is true");
>     else
>         writeln("implicit conversion is false");
>
>
> variable casting to bool is true
> constant casting to bool is false
> implicit conversion is true
>
> Now, casting any float constant in the interval (-1.0;1.0) to bool will return false, but the same value considered as an if condition or variable will always return true;
>
> Looking at disassembly, fcast2 is directly initialized to false, the compiler does not emit any conversion code:
>
> bool fcast2 = cast(bool)float.min_normal;
> 004174fa  mov byte [ebp-0x3], 0x0
>
> Is this intended behavior or it's a bug?

Raise a bug if you are unsure.