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digitalmars.D.bugs - [Issue 7826] New: [D2 Beta] Cannot use getHash in toHash without a warning

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=7826

           Summary: [D2 Beta] Cannot use getHash in toHash without a
                    warning
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: regression
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: cbkbbejeap mailinator.com


--- Comment #0 from Nick Sabalausky <cbkbbejeap mailinator.com> 2012-04-05
02:25:46 PDT ---
This code works in 2.058, even with warnings enabled:

------------------------
struct Foo
{
    string str;

    const hash_t toHash()
    {
        return typeid(string).getHash(&str);
    }
}
------------------------

But in the 2.059 beta:


dmd -c -w test.d


test.d(5): Warning: toHash() must be declared as extern (D) uint toHash() const
pure nothrow  safe, not const uint()

However, if the warning is is fixed, it *still* doesn't work:

------------------------
struct Foo
{
    string str;

    const pure nothrow  safe hash_t toHash()
    {
        return typeid(string).getHash(&str);
    }
}
------------------------

testToHash.d(7): Error: pure function 'toHash' cannot call impure function
'getHash'
testToHash.d(7): Error: & D12TypeInfo_Aya6__initZ.getHash is not nothrow
testToHash.d(5): Error: function testToHash.Foo.toHash 'toHash' is nothrow yet
may throw

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--- Comment #1 from Nick Sabalausky <cbkbbejeap mailinator.com> 2012-04-05
17:11:31 PDT ---
I don't know what the correct solution is supposed to be, but in any case it
should be possible to use getHash in toHash with warnings enabled.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug yahoo.com.au


--- Comment #2 from Don <clugdbug yahoo.com.au> 2012-04-06 00:35:06 PDT ---
Clearly if toHash() is required to be pure, getHash() must also be.
But I think it is unreasonable for the compiler to demand that toHash() be
pure, especially at the present time.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jmdavisProg gmx.com


--- Comment #3 from Jonathan M Davis <jmdavisProg gmx.com> 2012-04-06 00:49:29
PDT ---
I believe that tohash is among the functions which were decided must be  safe
const pure nothrow on classes. So, in that case, I would expect it to be
required (though not until Object is appropriately const-correct and whatnot).
But I don't see why  safe, const, pure, or nothrow should be required for
structs, since no inheritance is involved. With classes, with have to pick what
we want and use that for everything (possibly with some overloads which don't
have quite the same list of attributes), but structs don't have the same
requirements/restrictions.

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--- Comment #4 from github-bugzilla puremagic.com 2012-04-06 17:10:03 PDT ---
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/c324826ab425da4d2896b2d7abd97ebffcc0231b
fix Issue 7826 - [D2 Beta] Cannot use getHash in toHash without a warning

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Walter Bright <bugzilla digitalmars.com> changed:

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


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