Thread overview
[Issue 6708] New: immutable ref implicit cast to const ref
Jan 16, 2013
yebblies
Jan 16, 2013
yebblies
Jan 18, 2013
Walter Bright
September 21, 2011
http://d.puremagic.com/issues/show_bug.cgi?id=6708

           Summary: immutable ref implicit cast to const ref
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2011-09-21 13:48:10 PDT ---
I think this is correct code because foo and bar can't change the contents of arr and x in any way:


void foo(const ref int y) {}
void bar(const ref int[5] a1) {}
void spam(const ref int[] a2) {}
void baz(const ref int[int] aa) {}
void main() {
    immutable int x;
    foo(x); // Error?
    immutable int[5] arr1;
    bar(arr1); // Error?
    immutable int[] arr2;
    spam(arr2); // Error?
    immutable int[int] aa;
    baz(aa); // Error?
}


But DMD 2.055 gives errors:

test.d(7): Error: constant 0 is not an lvalue
test.d(9): Error: cast(const(int[5u]))arr1 is not an lvalue
test.d(11): Error: cast(const(int[]))arr2 is not an lvalue
test.d(13): Error: cast(const(int[int]))aa is not an lvalue


See also a thread on this topic in D.learn: http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learn&article_id=29609

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yebblies <yebblies@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull
                 CC|                            |yebblies@gmail.com
           Platform|x86                         |All
         AssignedTo|nobody@puremagic.com        |yebblies@gmail.com
         OS/Version|Windows                     |All


--- Comment #1 from yebblies <yebblies@gmail.com> 2013-01-17 01:58:11 EST ---
Only the first one gives an error now.  Happening because the const-folder is overly aggressive.

https://github.com/D-Programming-Language/dmd/pull/1496

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--- Comment #2 from yebblies <yebblies@gmail.com> 2013-01-17 02:06:19 EST ---
*** Issue 7225 has been marked as a duplicate of this issue. ***

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http://d.puremagic.com/issues/show_bug.cgi?id=6708



--- Comment #3 from github-bugzilla@puremagic.com 2013-01-17 18:45:15 PST ---
Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/704240e0d391cbf76f45d4d5e8e2a87454494e11 Fix Issue 6708 - immutable ref implicit cast to const ref

https://github.com/D-Programming-Language/dmd/commit/685d943a3af777621476239e200d895c6d375490 Merge pull request #1496 from yebblies/issue6708

Fix Issue 6708 - immutable ref implicit cast to const ref

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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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