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Issue 7694 - Internal error: e2ir.c 1251 when calling member function inside struct via alias param
Summary: Internal error: e2ir.c 1251 when calling member function inside struct via al...
Status: RESOLVED FIXED
Alias: None
Product: D
Classification: Unclassified
Component: dmd (show other issues)
Version: D2
Hardware: All All
: P2 major
Assignee: No Owner
URL:
Keywords: ice, pull
Depends on:
Blocks:
 
Reported: 2012-03-12 12:42 UTC by Dmitry Olshansky
Modified: 2012-03-28 22:51 UTC (History)
1 user (show)

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Description Dmitry Olshansky 2012-03-12 12:42:51 UTC 
As is the following gives assert on line 8 as expected, 
uncomment bootstrap to get Internal error: e2ir.c 1251

template Instruction(int ir)
{
    void match(alias s, alias  m)(){ m.nextState(); }
}


struct T{
    void nextState(){  assert(0); }
/*    void bootstrap()
    {
	return Instruction!(0).match!(this, this)();
    }*/
}

T t;
void main()
{

//  t.bootstrap();
  Instruction!(0).match!(t, t)();
}

on dmd 2.059head win7 x64
last commit: bcfd90aae05bd6259212ec870b2c037569029d77
Comment 1 Dmitry Olshansky 2012-03-22 12:34:05 UTC 
Minimized test case and a workaround:

void match(alias m)(){ 
	m.foo();//removing this line supresses ice in both cases
}

struct T{
    void foo(){}
    void bootstrap()
    {
//next line causes ice
//    	match!(this)();
//while this works:
	alias this p;
        match!(p)();

    }
}

void main(){}


Apaaerntly it has something to do with plain 'this' being mistreated in when passed as alias.
Comment 3 Kenji Hara 2012-03-23 22:50:19 UTC 
(In reply to comment #0)
> As is the following gives assert on line 8 as expected, 
> uncomment bootstrap to get Internal error: e2ir.c 1251
> 
> template Instruction(int ir)
> {
>     void match(alias s, alias  m)(){ m.nextState(); }
> }
> 
> 
> struct T{
>     void nextState(){  assert(0); }
> /*    void bootstrap()
>     {
>     return Instruction!(0).match!(this, this)();
>     }*/
> }
> 
> T t;
> void main()
> {
> 
> //  t.bootstrap();
>   Instruction!(0).match!(t, t)();
> }

With my pull, this code doesn't report ice, but raises following errors:

test.d(11): Error: template instance match!(this,this) cannot use local 'this' as parameter to non-global template match(alias s,alias m)
test.d(11): Error: template instance match!(this,this) cannot use local 'this' as parameter to non-global template match(alias s,alias m)

But I think this is a little harsh error. The nested template (function) match in module template Instruction really needs only one context, that is enclosing 'this' given as alias parameters m and n.
Comment 4 Dmitry Olshansky 2012-03-24 14:28:17 UTC 
I think the error is tolerable, when I found workaround I just rewrote it to global template. Less flexible maybe, but works for me.
Comment 5 github-bugzilla 2012-03-28 20:02:46 UTC 
Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/f8d472fed64a174472832d919f65b811fca0a968
Merge pull request #827 from 9rnsr/fix7694

Issue 7694 - Internal error: e2ir.c 1251 when calling member function inside struct via alias param