http://d.puremagic.com/issues/show_bug.cgi?id=1424

           Summary: is ( Type Identifier == function) Problems with
                    inout/out/ref parameters
           Product: D
           Version: 1.020
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: critical
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: dbiehl@gmx.net


Hi,

I have some strange problems with IsExpression and inout/out/ref parameters, first some code:

-------------- SNIP ---------------

//version = WithBar;
//version = BarWithParameterTypeTuple;
//version = DgWithParameterTypeTuple;
//version = WithAlsoFooParams;

import std.traits;
import std.stdio;

void foo(ref int i) {
}

static if (is(typeof(foo) P == function))
    alias P FooParams;
else
    static assert(0);

version(WithAlsoFooParams) {
    static if (is(typeof(foo) P == function))
        alias P AlsoFooParams;
    else
        static assert(0);
}

version(DgWithParameterTypeTuple) {
    void function(ParameterTypeTuple!(foo)) dg;
} else {
    void function(FooParams) dg;
}

version(WithBar) {
    version(BarWithParameterTypeTuple) {
        void bar(ParameterTypeTuple!(foo)) {
        }
    } else {
        void bar(FooParams) {
        }
    }
}
int main(string[] args)
{

    int i = 0;

    writefln(typeof(&foo).stringof);
    writefln(typeof(dg).stringof);
    version(WithBar)
        writefln(typeof(&bar).stringof);

    return 0;
}

-------------- SNIP ---------------

I first define a function "foo", now I want to define a delegate "dg" with the same parameters as foo. I get the parmeter tuple of foo with the isExpression. The output of the code is:

    void(*)((ref int))
    void(*)((ref int))

how it should be. Now want to define a second function "bar" with the same parameters as foo (Simple uncomment the first line "version = WithBar;"), I thought the output is something like this, with a ref-Parameter:

    void(*)((ref int))
    void(*)((ref int))
    void(*)((ref int))

but the output is:

    void(*)((int _param_0))
    void(*)((int _param_0))
    void(*)((int _param_0))

where is the ref parameter in all lines?

Now get the parameter tuple of foo for function bar with the std.traits.ParameterTypeTuple template. (uncomment the second line "version = BarWithParameterTypeTuple;") The output is:

void(*)((ref int))
void(*)((ref int))
void(*)((int _param_0))

where is the ref in the last line?

until here everything compiles fine, but now I define a second alias of the parameter tuples of foo (uncomment the 4. line "version = WithAlsoFooParams" the and I get "Stack Overflow" from the DMD compiler and GDC hangs.

I try it with DMD versions 1.020, 2.003 and a SVN Trunk Version (Rev 139) of
GDC .

Greets Daniel


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1424


Harry Vennik <htvennik@zonnet.nl> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |htvennik@zonnet.nl


--- Comment #1 from Harry Vennik <htvennik@zonnet.nl> 2010-04-26 06:44:29 PDT ---
I think the point is that 'ref' is a storage class, not part of the parameter's type. Therefore it isn't preserved in TypeTuples theoretically. In practice the 'ref' is preserved in the result of ParameterTypeTuple!(), but using that in a template to define the parameters of a templated function, will only take the types, not the 'ref'.

It's not always practical like this, and it makes me write a lot of
work-arounds, but solving this issue in D is problematic. It either requires
one of:
- make type tuples preserve storage class (and how to get rid of it then, if
you don't want it to be preserved?)
- make 'ref' and 'out' part of the type (and what about 'lazy' then? make it
unfold to a delegate type?)

I don't really feel for either one...

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http://d.puremagic.com/issues/show_bug.cgi?id=1424


yebblies <yebblies@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |yebblies@gmail.com
         Resolution|                            |DUPLICATE


--- Comment #2 from yebblies <yebblies@gmail.com> 2011-06-10 10:47:20 PDT ---
Marking as a duplicate as the report seems to expect this behaviour.

*** This issue has been marked as a duplicate of issue 1818 ***

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