http://d.puremagic.com/issues/show_bug.cgi?id=6940

           Summary: immutable(int*)* and int** do not combine
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: timon.gehr@gmx.ch


--- Comment #0 from timon.gehr@gmx.ch 2011-11-12 13:34:54 PST ---
immutable(int*)* and int** do not combine even though const(int*)* would be a
common type:

immutable(int*)*    x;
int**               y;

static assert(is(typeof(x) : const(int*)*)); // ok
static assert(is(typeof(y) : const(int*)*)); // ok
static assert(is(typeof(1?x:y)));            // fail


Compare to dynamic arrays:

immutable(int[])[]  a;
int[][]             b;

static assert(is(typeof(a) : const(int[])[])); // ok
static assert(is(typeof(b) : const(int[])[])); // ok
static assert(is(typeof(1?a:b)));              // ok

(why on earth do the two cases use different logic?)

Therefore the following could be used as a workaround:

static assert(is(typeof((1?x[0..1]:y[0..1]).ptr)));

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--- Comment #1 from Kenji Hara <k.hara.pg@gmail.com> 2011-11-16 19:44:01 PST ---
> static assert(is(typeof(x) : const(int*)*)); // ok

> static assert(is(typeof(a) : const(int[])[])); // ok

I think these two lines should not compile.
They are the part of bug 4251.

Then, Both two cases should not have common type, IMO.

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--- Comment #2 from timon.gehr@gmx.ch 2011-11-17 11:40:16 PST ---
(In reply to comment #1)
> > static assert(is(typeof(x) : const(int*)*)); // ok
> 
> > static assert(is(typeof(a) : const(int[])[])); // ok
> 
> I think these two lines should not compile.
> They are the part of bug 4251.
> 
> Then, Both two cases should not have common type, IMO.

No, they are not part of bug 4251. This bug report is valid.

This is bug 4251:

immutable(int)** x;
immutable(int)[][] y;

static assert(is(typeof(x): const(int)**));
static assert(is(typeof(y): const(int)[][]));

Consider this:

immutable(int)** x;
int y;
// we now make *x point to y, even though y is not immutable:
const(int)** p = x; // bug 4251
*p=&y; // since p == x, this assigns &y to *x

That only works because immutable converted to const _two references deep_.

None of that is going on here, consider this:

immutable(int*)* x
int y;
// we now try to do the same thing
const(int*)* p = x; // assume this works
*p = y; // error!

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timon.gehr@gmx.ch changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|immutable(int*)* and int**  |immutable(int*)*/immutable(
                   |do not combine              |int)** and int** do not
                   |                            |combine


--- Comment #3 from timon.gehr@gmx.ch 2011-11-18 13:35:48 PST ---
immutable(int)** and int** should also combine to const(int*)*

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch, rejects-valid


--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2011-12-19 07:11:36 PST ---
https://github.com/D-Programming-Language/dmd/pull/571

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@digitalmars.com
         Resolution|                            |FIXED


--- Comment #5 from Walter Bright <bugzilla@digitalmars.com> 2011-12-20 13:03:08 PST ---
https://github.com/D-Programming-Language/dmd/commit/06fe1ce97ef56cb86821114024c55f8d5fe0073c

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