http://d.puremagic.com/issues/show_bug.cgi?id=1730

           Summary: const struct member func return invariant string can't
                    assign to invariant string
           Product: D
           Version: 2.008
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: davidl@126.com


struct mystruct{
        invariant(char)[] toChars()
        {
                return "asdf";
        }
}
void func(in mystruct s)
{
        invariant(char)[] k=s.toChars;
}

testconst.d(9): function testconst.mystruct.toChars () does not match parameter
types ()
testconst.d(9): Error: s.toChars can only be called on a mutable object, not
const(mystruct)


-- 

On 12/14/07, d-bugmail@puremagic.com <d-bugmail@puremagic.com> wrote:
> struct mystruct{
>         invariant(char)[] toChars()
>         {
>                 return "asdf";
>         }
> }
> void func(in mystruct s)
> {
>         invariant(char)[] k=s.toChars;
> }

That's correct behaviour, surely?

Change the function definition to

    const invariant(char)[] toChars()
    {
        return "asdf";
    }

and the problem should go away. toChars() as written is incorrectly declared. It does not modify this, therefore it should be declared const.

That said, I don't understant how s got to be const in the first place! Does "in" make things const?

http://d.puremagic.com/issues/show_bug.cgi?id=1730


davidl@126.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor
           Keywords|rejects-valid               |
            Summary|const struct member func    |error message enhance?
                   |return invariant string     |
                   |can't assign to invariant   |
                   |string                      |




------- Comment #2 from davidl@126.com  2007-12-15 07:40 -------
But at least the first error message is confusing.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1730



--- Comment #3 from Stewart Gordon <smjg@iname.com> 2009-11-20 11:10:48 PST ---
Probably part of the same bug:

----------
class Class {
    void fn1() const {
        fn2();
    }

    void fn2() {}
}
----------
const_call.d(3): Error: function const_call.Class.fn2 () is not callable using
argument types () const
----------

This may make sense at the internal level, as trying to convert the 'this' argument implicitly from const(Class) to Class.  But as a user error message, it's confusing.

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Michal Spadlinski <gim913@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gim913@gmail.com


--- Comment #4 from Michal Spadlinski <gim913@gmail.com> 2010-03-13 07:25:52 PST ---
I has similar problem with:

struct Foo {
    bool boo() {
        return false;
    }

    int foo () const {
        assert (boo);
        return 66;
    }
}

this message is totally misleading

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason.james.house@gmail.com


--- Comment #5 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-12-23 13:45:29 PST ---
*** Issue 3642 has been marked as a duplicate of this issue. ***

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mrmocool@gmx.de


--- Comment #6 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-12-23 13:45:34 PST ---
*** Issue 4497 has been marked as a duplicate of this issue. ***

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #7 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-12-23 13:47:23 PST ---
There's a ton of duplicate reports on this diagnostic. We better come up with a better error message than what we have now because there's a lot of complaints.

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull
         AssignedTo|nobody@puremagic.com        |andrej.mitrovich@gmail.com


--- Comment #8 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-12-25 06:31:46 PST ---
https://github.com/D-Programming-Language/dmd/pull/1407

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--- Comment #9 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-12-27 17:43:17 PST ---
*** Issue 6707 has been marked as a duplicate of this issue. ***

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