Why the program produced from the following code enters loop which ends with the message: "Error: Access Violation"?

import std.c.stdio;

typedef u *u();

u *s()
{
 static int x = 0;
 printf("%d\n", x++);
 return s;
}

int main(){
 s();
 return 0;
}

For the below code the compiler (v0.119) reports "Internal error:
..\ztc\cgcod.c 1445":

import std.c.stdio;

typedef u *u();

u s()
{
 static int x = 0;
 printf("%d\n", x++);
 return s;
}

int main(){
 s();
 return 0;
}

Thank you,
Brian

On Wed, 23 Mar 2005 20:00:36 +0200, Brian Gardner <briangr@friberg.us> wrote:
> Why the program produced from the following code enters loop which ends with
> the message: "Error: Access Violation"?
>
> import std.c.stdio;
>
> typedef u *u();
>
> u *s()
> {
>  static int x = 0;
>  printf("%d\n", x++);
>  return s;
> }
>
> int main(){
>  s();
>  return 0;
> }

My guess is that the "return s;" statement in the "s" function calls the "s" function again.

> For the below code the compiler (v0.119) reports "Internal error:
> ..\ztc\cgcod.c 1445":
>
> import std.c.stdio;
>
> typedef u *u();
>
> u s()
> {
>  static int x = 0;
>  printf("%d\n", x++);
>  return s;
> }
>
> int main(){
>  s();
>  return 0;
> }

This is a bug with DMD.

I have cross-posted my reply to the digitalmars.d.bugs group.

Regan

In article <opsn4csyii23k2f5@nrage.netwin.co.nz>, Regan Heath says...
>
>On Wed, 23 Mar 2005 20:00:36 +0200, Brian Gardner <briangr@friberg.us> wrote:
>> Why the program produced from the following code enters loop which ends
>> with
>> the message: "Error: Access Violation"?
>>
>> import std.c.stdio;
>>
>> typedef u *u();
>>
>> u *s()
>> {
>>  static int x = 0;
>>  printf("%d\n", x++);
>>  return s;
>> }
>>
>> int main(){
>>  s();
>>  return 0;
>> }
>
>My guess is that the "return s;" statement in the "s" function calls the "s" function again.

Isn't s (in "return s;") a pointer to function according to D? If not, how to obtain a pointer to function s without calling s?

Thanks,
Brian

Regan Heath wrote:

| On Wed, 23 Mar 2005 20:00:36 +0200, Brian Gardner <briangr@friberg.us>
| wrote:

<snip>

|> For the below code the compiler (v0.119) reports "Internal error:
|> ..\ztc/cgcod.c 1445":
|>
|> import std.c.stdio;
|>
|> typedef u *u();
|>
|> u s()
|> {
|>  static int x = 0;
|>  printf("%d\n", x++);
|>  return s;
|> }
|>
|> int main(){
|>  s();
|>  return 0;
|> }
|
|
| This is a bug with DMD.
|
| I have cross-posted my reply to the digitalmars.d.bugs group.

Added to DStress as
http://dstress.kuehne.cn/nocompile/bug_cgcod_1445_A.d
http://dstress.kuehne.cn/nocompile/bug_cgcod_1445_B.d

Thomas

On Thu, 24 Mar 2005 13:55:07 +0000 (UTC), Brian Gardner <Brian_member@pathlink.com> wrote:
> In article <opsn4csyii23k2f5@nrage.netwin.co.nz>, Regan Heath says...
>>
>> On Wed, 23 Mar 2005 20:00:36 +0200, Brian Gardner <briangr@friberg.us>
>> wrote:
>>> Why the program produced from the following code enters loop which ends
>>> with
>>> the message: "Error: Access Violation"?
>>>
>>> import std.c.stdio;
>>>
>>> typedef u *u();
>>>
>>> u *s()
>>> {
>>>  static int x = 0;
>>>  printf("%d\n", x++);
>>>  return s;
>>> }
>>>
>>> int main(){
>>>  s();
>>>  return 0;
>>> }
>>
>> My guess is that the "return s;" statement in the "s" function calls the
>> "s" function again.
>
> Isn't s (in "return s;") a pointer to function according to D?
> If not, how to obtain a pointer to function s without calling s?

http://www.digitalmars.com/d/function.html#closures

import std.stdio;

typedef fn function(int) fn;

fn foo(int i){
	writefln("foo called (",i,")");
	return &foo;
}

void main()
{
	fn p = foo(1);
	p(2);
}

Regan

The trouble with both examples is the:

    typedef u *u();

which is a circular reference. The compiler now issues a diagnostic.