• d-bugmail puremagic.com Apr 28 2008
• d-bugmail puremagic.com May 28 2008
• d-bugmail puremagic.com Nov 17 2010
• d-bugmail puremagic.com Nov 17 2010
• d-bugmail puremagic.com Nov 18 2010
• d-bugmail puremagic.com Nov 18 2010
• d-bugmail puremagic.com Nov 19 2010

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=2056

           Summary: Const system does not allow certain safe
                    casts/conversions involving deep composite types
           Product: D
           Version: 2.013
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: critical
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: brunodomedeiros+bugz gmail.com


Const system does not allow certain safe casts/conversions involving deep
composite types. In the following example, all casts should be allowed.
----

void testcases()
{
        int[][] intArrayArray;
        int[][][] intArrayArrayArray;


        const(int)[][] f1 = intArrayArray; // Error here
        const(int[])[] f2 = intArrayArray; 

        const(int)[][][] g1 = intArrayArrayArray; // Error here
        const(int[])[][] g2 = intArrayArrayArray; // Error here
        const(int[][])[] g3 = intArrayArrayArray;

}


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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=2056





------- Comment #1 from brunodomedeiros+bugz gmail.com  2008-05-28 16:09 -------
I'm not sure if I should open a new bug or not, but since this one is still
open, I'll put it here.

The array cases seem to be fixed in DMD 2.14, but the very same problem still
exists with pointer types, for example:

void testcases()
{
        int** intPtrPtr;
        int*** intPtrPtrPtr;

        const(int)** h1 = intPtrPtr; // Error here
        const(int*)* h2 = intPtrPtr;

        const(int)*** i1 = intPtrPtrPtr; // Error here
        const(int*)** i2 = intPtrPtrPtr; // Error here
        const(int**)* i3 = intPtrPtrPtr;

}

Similar issues also exist for associative arrays.


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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=2056


Bruno Medeiros <bdom.pub+deebugz gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


--- Comment #2 from Bruno Medeiros <bdom.pub+deebugz gmail.com> 2010-11-17
12:15:17 PST ---
The latest DMD compiles both code samples now, *however*, I've come to realize
that in fact this code should NOT be allowed (that is, any of the "Error here"
lines in the code above should produce an error), because these casts are
actually not safe.

For the reasons why, see bug #2544 , which is the inverse of this one.

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--- Comment #3 from Sobirari Muhomori <dfj1esp02 sneakemail.com> 2010-11-17
14:21:51 PST ---
So this is a regression?

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--- Comment #4 from Bruno Medeiros <bdom.pub+deebugz gmail.com> 2010-11-18
04:06:29 PST ---
A regression? Not exactly. 
When this bug was submitted, the lines marked with "// Error here" did not
compile, and that was the "bug" that was reported. At some point DMD was
changed so that the first, and later both code samples above compiled without
errors. (I don't know if it was because Walter tried to fix this "bug"
specifically, or if it was due to some other DMD changes).
So this "bug" became fixed, but as I found after seeing #2544, this "bug" is
actually invalid, and should not have been fixed in the first place.

( For curiosity, it would only be valid if immutable did not exist, or more
precisely, if T was the only subtype of const(T) )

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--- Comment #5 from Sobirari Muhomori <dfj1esp02 sneakemail.com> 2010-11-18
12:11:28 PST ---
 When this bug was submitted, the lines marked with "// Error here" did not
 compile


So what does the fix for bug 3621, I wonder? (It's for dmd 2.038)

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--- Comment #6 from Bruno Medeiros <bdom.pub+deebugz gmail.com> 2010-11-19
15:20:41 PST ---
(In reply to comment #5)
 When this bug was submitted, the lines marked with "// Error here" did not
 compile


 So what does the fix for bug 3621, I wonder? (It's for dmd 2.038)


I don't know. The code sample in #3621 still compiles ok, so maybe it was a
mistake from Walter's part, and the bug is not really fixed. Just like #2544 is
not fixed.

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