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digitalmars.D.bugs - [Issue 4935] New: std.bitmanip: bitfields!() template with trailing unnamed field does not work

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4935

           Summary: std.bitmanip: bitfields!() template with trailing
                    unnamed field does not work
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: ah08010-d yahoo.com



PDT ---
Despite the documentation in the library reference manual, a nameless field
cannot be set as the "last" entry in a list of bit fields:

This code:
==========
module scratch;
import std.bitmanip;

version(unittest) {
    void main() { }
}

struct S {
    mixin(bitfields!(
        uint, "some", 4,
    uint, "", 4                     
    ));
}
==========
Produces this error:
==========
$ dmd -unittest -run bronze/util/scratch.d
bronze\util\scratch.d(14): Error: variable scratch.S.some conflicts with
function scratch.S.some at bronze\util\scratch.d(12)
==========
Strangely, leading nameless fields are okay. This code compiles fine:
==========
struct S {
    mixin(bitfields!(
        uint, "", 1,
        uint, "", 1,
        uint, "some", 4,
        uint, "last", 2                 
    ));
}
==========

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Sep 24 2010
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4935


Mitch Hayenga <mitch.hayenga gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mitch.hayenga gmail.com



PDT ---
Ahh, I hit this myself a few days ago.  My fields are now named "ignore1",
"ignroe2", etc.  I thought it was maybe my mistake because I was trying to do
something like...

struct Instruction{
  union{
    mixin(bitfields!(
      ubyte, "imm", 4,
      ubyte, "rot", 4,
      ubyte, "",    4,
      ubyte, "opcode", 4));

    // Read the bottom 8 bits as a longer immediate
    mixin(bitfields!( 
      ubyte, "imm8", 8,
      ubyte, "", 8));
  }
}

And was unsure about bitfields support within union type structures.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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PDT ---
Entertainingly, this is the "real" code I was trying to work on:

union Instruction {
    ushort raw;

    // Basic opcode + data
    mixin(bitfields!(
                 Opcode, "opcode", 7,
                 uint, "rest", 9));

Is it only people working with opcodes that want to use bitfields? :)

Also, I think I'm going to request that repeated bitfield definitions be
allowed if they are identical - I'd like to redeclare "opcode" rather than "".

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Andrei Alexandrescu <andrei metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei metalanguage.com
         AssignedTo|nobody puremagic.com        |andrei metalanguage.com


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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Era Scarecrow <rtcvb32 yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rtcvb32 yahoo.com



---
I was unable to duplicate this problem, so either DMD already fixed some bug,
or my patches already fixed it.


 And was unsure about bitfields support within union type structures.


 Inside a union it should be fine, as only one variable is made that's
accessible (although enums are present). If those give you trouble, you can use
bitfieldsOn (in my branch) to specify a specific variable elsewhere that you
want to use for your source.

 Once the pull is accepted I'm changing this status to resolved.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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PST ---
 Era: what pull are you referring to?

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prev sibling parent d-bugmail puremagic.com writes:
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safety0ff.bugz <safety0ff.bugz gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |safety0ff.bugz gmail.com



09:26:00 PDT ---


  Era: what pull are you referring to?


He seems to have been referring to pull requests: 1045, 719, 734 and 740 (all
closed unmerged.)

This seems to have been fixed prior to 2.060, I'll end up writing a unittest to
make sure it stays that way.

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