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November 12, 2012
Pointer to string allows assigning int[]?
Is the following a bug?

import std.c.string, core.memory;

void* makeNew(T)()
{
    T t = T.init;
    void* ptr = GC.malloc(T.sizeof);
    memcpy(ptr, &t, T.sizeof);
    return ptr;
}

void main()
{
    alias string T;
    T* iptr = cast(T*)makeNew!(T);
    (*iptr) = [1,2,3]; // this is allowed
}
November 12, 2012
Re: Pointer to string allows assigning int[]?
On Monday, 12 November 2012 at 21:03:51 UTC, cal wrote:
> Is the following a bug?
>
> import std.c.string, core.memory;
>
> void* makeNew(T)()
> {
>     T t = T.init;
>     void* ptr = GC.malloc(T.sizeof);
>     memcpy(ptr, &t, T.sizeof);
>     return ptr;
> }
>
> void main()
> {
>     alias string T;
>     T* iptr = cast(T*)makeNew!(T);
>     (*iptr) = [1,2,3]; // this is allowed
> }

It's not a bug.

string is an alias for immutable(char)[].
ubyte can be implicitly converted to char.
All your numbers are less than 256, so dmd is able to convert 
them to char.
If you try this, it fails.
string s = [256]; // 256 is > char.max
November 12, 2012
Re: Pointer to string allows assigning int[]?
On Monday, 12 November 2012 at 21:08:43 UTC, simendsjo wrote:
> It's not a bug.
>
> string is an alias for immutable(char)[].
> ubyte can be implicitly converted to char.
> All your numbers are less than 256, so dmd is able to convert 
> them to char.
> If you try this, it fails.
> string s = [256]; // 256 is > char.max

Ah right of course, thank you.
November 12, 2012
Re: Pointer to string allows assigning int[]?
On 11/12/12, cal <callumenator@gmail.com> wrote:
> Is the following a bug?

Reduced:

void main()
{
   string x = "foo";
   string* y = &x;
   *y = [1, 2, 3];
   assert(x == "foo"); // fails
}

Yes this is a bug, especially since the string is typed as immutable(char)[].
November 12, 2012
Re: Pointer to string allows assigning int[]?
On 11/12/12, simendsjo <simendsjo@gmail.com> wrote:
> It's not a bug.

It's a bug, he's overwriting immutable data.
November 12, 2012
Re: Pointer to string allows assigning int[]?
On 11/12/12, Andrej Mitrovic <andrej.mitrovich@gmail.com> wrote:
> On 11/12/12, simendsjo <simendsjo@gmail.com> wrote:
>> It's not a bug.
>
> It's a bug, he's overwriting immutable data.
>

Ahh sorry I completely misread the code. There's no bug here actually.
November 12, 2012
Re: Pointer to string allows assigning int[]?
On 11/12/12, Andrej Mitrovic <andrej.mitrovich@gmail.com> wrote:
> Yes this is a bug, especially since the string is typed as
> immutable(char)[].
>

My bad, the string contents aren't being modified. Not a bug.
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