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digitalmars.D.bugs - [Issue 6611] New: array[]++ and array[]-- too?

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6611

           Summary: array[]++ and array[]-- too?
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc



This code contains two operations that are refused by DMD2.055beta:

void main() {
    int[10] a;
    a[] += 1; // OK
    ++a[];    // OK
    --a[];    // OK
    a[]++;    // line 6, error
    a[]--;    // line 7, error
}


test2.d(6): Error: slice expression a[] is not a modifiable lvalue
test2.d(6): Error: 'a[]' is not a scalar, it is a int[]
test2.d(6): Error: cannot cast int to int[]
test2.d(7): Error: slice expression a[] is not a modifiable lvalue
test2.d(7): Error: 'a[]' is not a scalar, it is a int[]
test2.d(7): Error: cannot cast int to int[]


Maybe it's better to allow the last two lines too.

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Sep 06 2011
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6611


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |yebblies gmail.com



This line implies the following
a[]++ => (auto tmp = a[].dup, ++a[], tmp)

Do we really want it to be this easy to do?

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prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6611






 This line implies the following
 a[]++ => (auto tmp = a[].dup, ++a[], tmp)
 
 Do we really want it to be this easy to do?


I understand. If doing this is not good, then I suggest to turn this into a
diagnostic enhancement request. So given code like this:

void main() {
    int[10] a;
    a[]++;
}


to raise a single error message that explains why that vector op is on purpose
not supported.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6611






 I understand. If doing this is not good, then I suggest to turn this into a
 diagnostic enhancement request. So given code like this:
 


It's probably not worth introducing yet another hidden allocation, or a special
case as it can be easily written using pre-inc.


 void main() {
     int[10] a;
     a[]++;
 }
 
 
 to raise a single error message that explains why that vector op is on purpose
 not supported.


That sounds reasonable, the error message is terrible.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull



https://github.com/D-Programming-Language/dmd/pull/717

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Feb 14 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6611




Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/176b8752c6f9d92e2570bcb47b87419bf2f0ccd2
Issue 6611 - better error message for array post increment/decrement

Detect attempts to use post increment/decrement on an array slice, and print a
better error message.

https://github.com/D-Programming-Language/dmd/commit/d082916311aca3d14e13295eaafa9b6e52cd81b3


Issue 6611 - better error message for array post increment/decrement

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Feb 18 2012
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6611


Walter Bright <bugzilla digitalmars.com> changed:

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


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