http://d.puremagic.com/issues/show_bug.cgi?id=4767

           Summary: dmd generates useless template bloat
           Product: D
           Version: D1 & D2
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: nfxjfg@gmail.com


--- Comment #0 from nfxjfg@gmail.com 2010-08-29 20:36:13 PDT ---
Merely importing a file that contains template can make dmd generate code. This not only increases compile times, but it also can be the reason for severe exe bloat: often the linker will pull in completely unrelated modules just to get symbols for instantiated templates (the bloat is then caused by unrelated symbols that have been unnecessarily been pulled in).

$ cat a.d
module a;
import b;

$ cat b.d
module b;

struct Bloat(T)
{
    void foo() {
    }
}

class NotBloat
{
    this(Bloat!(uint) x)
    {
    }
}

$ dmd -c a.d

$ nm a.o|grep Bloat
00000000 W _D1b12__T5BloatTkZ5Bloat3fooMFZv
00000000 V _D1b12__T5BloatTkZ5Bloat6__initZ
00000000 V _D32TypeInfo_S1b12__T5BloatTkZ5Bloat6__initZ

a.d only imports b.d, yet there's this crap in a.o.

Obviously dmd should not generate code in this case.

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nfxjfg@gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX


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Brad Roberts <braddr@puremagic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |braddr@puremagic.com
         Resolution|WONTFIX                     |


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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla@digitalmars.com


--- Comment #1 from Walter Bright <bugzilla@digitalmars.com> 2011-04-11 21:39:51 PDT ---
What matters is what gets into the exe file, not what's in the object files.

To that end, if you use dmd to generate a library file from source, it will split each object file into multiple ones (one for each global symbol). Then, only the referenced symbols get pulled in.

It's not a perfect solution, but it's a start.

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