• via Digitalmars-d-bugs (82/82) Jul 12 2016 https://issues.dlang.org/show_bug.cgi?id=16270

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=16270

          Issue ID: 16270
           Summary: scoped Alignment
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: TeddyBear12311 gmail.com

C++ has the ability to align all members of struct/class in a scope: e.g.,
#pragma pack(push,16)

Without this in D, it requires aligning each type manually. It may seem like
trivial work, but it is not and posses serious problems when converting C code
that uses scoped alignment. 

A simple

align(n)
{
   struct x { int a, b, c; }
}

would be identical do

align(n) struct x
{
   align(n)
      int a, b, c;
}

It should be a trivial enhancement.  I'm only concerned about the member
alignment.

Alternatives are


align(n)
{
   struct x { int a, b, c; }
}

would be identical do

struct x
{
   align(n)
      int a, b, c;
}

or

malign(n)
{
   struct x { int a, b, c; }
}

would be identical do

struct x
{
   align(n)
      int a, b, c;
}



pragma could be used



pragma(align(n)) 

struct x { int a, b, c; }
struct y { int a, b, c; }

pragma(align(m)) 
struct z { int a, b, c; }



would be identical do

struct x
{
   align(n)
      int a, b, c;
}

struct y
{
   align(n)
      int a, b, c;
}

struct z
{
   align(m)
      int a, b, c;
}


The responses that a simply search and replace are not acceptable. It is not
robust, may quietly fail, etc. Adding by hand to every struct or member is also
not acceptable because because it depends on size. (trivial for one struct but
not so for 100 structs)

I believe this is not an enhancement but an oversight.  It is required for
large complex code unless man hours is not a factor.

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