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Is the following code legal, illegal or undefined?

void test(){
	const int a;
	int b;
	static if(a==3){
		...
	} else if(b==2){
		...
	}
}

http://dstress.kuehne.cn/undefined/static_if_05_A.d http://dstress.kuehne.cn/undefined/static_if_05_B.d

Thomas


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Isn't that the same as:

void test()
{
	const int a;
	int b;

	static if (a == 3)
	{
		// ...
	}
	else
	{
		if (b == 2)
		{
			// ...
		}
	}
}

Which is totally legal...?

-[Unknown]


> -----BEGIN PGP SIGNED MESSAGE-----
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> 
> Is the following code legal, illegal or undefined?
> 
> void test(){
> 	const int a;
> 	int b;
> 	static if(a==3){
> 		...
> 	} else if(b==2){
> 		...
> 	}
> }
> 
> http://dstress.kuehne.cn/undefined/static_if_05_A.d
> http://dstress.kuehne.cn/undefined/static_if_05_B.d
> 
> Thomas
> 
> 
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> vS8vTWaFfxXNFUKdTIkhJaY=
> =LdZW
> -----END PGP SIGNATURE-----

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Unknown W. Brackets schrieb am Fri, 10 Jun 2005 10:59:58 -0700:
> Isn't that the same as:
>
> void test()
> {
> 	const int a;
> 	int b;
>
> 	static if (a == 3)
> 	{
> 		// ...
> 	}
> 	else
> 	{
> 		if (b == 2)
> 		{
> 			// ...
> 		}
> 	}
> }
>
> Which is totally legal...?

Ok, a bit more complex:

void test()
{
	cont int a;
	int b;

	if (b==1){
		// ...
	}else static if(a==2){
		// ...
		int c;
	}else if(b==3){
		// ...
	}
}


Can't be rewritten in the same way.
c and b are in the same scope but would be in different scopes in the
rewrite.

Thomas


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Apparently not, as you can see in d.D.announce under the dmd.126 announcement, I was having trouble with 'else if' vs 'static else if', and you can see the difference with the sample code I attached (my last example, I posted the wrong one at first).


Unknown W. Brackets wrote:
> Isn't that the same as:
> 
> void test()
> {
>     const int a;
>     int b;
> 
>     static if (a == 3)
>     {
>         // ...
>     }
>     else
>     {
>         if (b == 2)
>         {
>             // ...
>         }
>     }
> }
> 
> Which is totally legal...?
> 
> -[Unknown]
> 
> 
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> Is the following code legal, illegal or undefined?
>>
>> void test(){
>>     const int a;
>>     int b;
>>     static if(a==3){
>>         ...
>>     } else if(b==2){
>>         ...
>>     }
>> }
>>
>> http://dstress.kuehne.cn/undefined/static_if_05_A.d
>> http://dstress.kuehne.cn/undefined/static_if_05_B.d
>>
>> Thomas
>>
>>
>> -----BEGIN PGP SIGNATURE-----
>>
>> iD8DBQFCqczs3w+/yD4P9tIRAo6kAJwOP8qYWovTFgJWhWLx+ZLlo5K4ygCgnplj
>> vS8vTWaFfxXNFUKdTIkhJaY=
>> =LdZW
>> -----END PGP SIGNATURE-----

Well, imho, that *should* be exactly the same as:

void test()
{
	const int a;
	int b;

	if (b == 1)
	{
	}
	else // <-- this is the else I'm talking about.
	{
		static if (a == 2)
		{
			int c; // <-- visible inside whole else above.
		}
		else
		{
			// One couldn't use c here, though.
			if (b == 3)
			{
			}
		}
	}
}

If it's not currently, I'd say that it's the bug.

-[Unknown]


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> Hash: SHA1
> 
> Unknown W. Brackets schrieb am Fri, 10 Jun 2005 10:59:58 -0700:
> 
>>Isn't that the same as:
>>
>>void test()
>>{
>>	const int a;
>>	int b;
>>
>>	static if (a == 3)
>>	{
>>		// ...
>>	}
>>	else
>>	{
>>		if (b == 2)
>>		{
>>			// ...
>>		}
>>	}
>>}
>>
>>Which is totally legal...?
> 
> 
> Ok, a bit more complex:
> 
> void test()
> {
> 	cont int a;
> 	int b;
> 
> 	if (b==1){
> 		// ...
> 	}else static if(a==2){
> 		// ...
> 		int c;
> 	}else if(b==3){
> 		// ...
> 	}
> }
> 
> 
> Can't be rewritten in the same way.
> c and b are in the same scope but would be in different scopes in the
> rewrite.
> 
> Thomas
> 
> 
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> -----END PGP SIGNATURE-----

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Unknown W. Brackets schrieb am Fri, 10 Jun 2005 13:51:00 -0700:
> Well, imho, that *should* be exactly the same as:
>
> void test()
> {
> 	const int a;
> 	int b;
>
> 	if (b == 1)
> 	{
> 	}
> 	else // <-- this is the else I'm talking about.
> 	{
> 		static if (a == 2)
> 		{
> 			int c; // <-- visible inside whole else above.
> 		}
> 		else
> 		{
> 			// One couldn't use c here, though.
> 			if (b == 3)
> 			{
> 			}
> 		}
> 	}
	b+=c;
> }
>
> If it's not currently, I'd say that it's the bug.

Now add "b+=c;" to the end.
Before the rewrite b and c were declared in the same scope.
After the rewrite b and c are declared in different scopes.

Thomas


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Thomas Kuehne schrieb am Fri, 10 Jun 2005 23:08:54 +0200:
>
>
> Unknown W. Brackets schrieb am Fri, 10 Jun 2005 13:51:00 -0700:
>> Well, imho, that *should* be exactly the same as:
>>
>> void test()
>> {
>> 	const int a;
>> 	int b;
>>
>> 	if (b == 1)
>> 	{
>> 	}
>> 	else // <-- this is the else I'm talking about.
>> 	// **A** {
>> 		static if (a == 2)
>> 		{
>> 			int c; // <-- visible inside whole else above.
>> 		}
>> 		else
>> 		{
>> 			// One couldn't use c here, though.
>> 			if (b == 3)
>> 			{
>> 			}
>> 		}
>> 	// **B** }
> 	b+=c;
>> }
>>
>> If it's not currently, I'd say that it's the bug.
>
> Now add "b+=c;" to the end.
> Before the rewrite b and c were declared in the same scope.
> After the rewrite b and c are declared in different scopes.

Allright, the scopeless "static if" can be a bit confusing at first. Remove the brackets A and B and everything turns legal and documented.

Thomas


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No, there's no bug. It's well defined. static-if-else is a *completely different* statement than if-else. It might make more sense to if you replace "static if(a == 3)" with "version (identifier)", as version-else and static-if-else are very analogous in their behavior.

Thomas Kuehne wrote:
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> 
> Thomas Kuehne schrieb am Fri, 10 Jun 2005 23:08:54 +0200:
> 
>>
>>Unknown W. Brackets schrieb am Fri, 10 Jun 2005 13:51:00 -0700:
>>
>>>Well, imho, that *should* be exactly the same as:
>>>
>>>void test()
>>>{
>>>	const int a; 	int b;
>>>
>>>	if (b == 1)
>>>	{
>>>	}
>>>	else // <-- this is the else I'm talking about.
>>>	// **A** {
>>>		static if (a == 2)
>>>		{
>>>			int c; // <-- visible inside whole else above.
>>>		}
>>>		else
>>>		{
>>>			// One couldn't use c here, though.
>>>			if (b == 3)
>>>			{
>>>			}
>>>		}
>>>	// **B** }
>>
>>	b+=c;
>>
>>>}
>>>
>>>If it's not currently, I'd say that it's the bug.
>>
>>Now add "b+=c;" to the end. Before the rewrite b and c were declared in the same scope.
>>After the rewrite b and c are declared in different scopes.
> 
> Allright, the scopeless "static if" can be a bit confusing at first.
> Remove the brackets A and B and everything turns legal and documented.
<snip>

Legal?  The outermost else block is of a normal if, not a static if, and therefore it creates a scope.  Why should whether the body is a BlockStatement or not make a difference?  It makes no sense, since whether or not c is declared would depend at runtime on whether b == 1.

Documented?  Where?

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on the 'group where everyone may benefit.

Thomas Kuehne wrote:
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> Hash: SHA1
> 
> Is the following code legal, illegal or undefined?
> 
> void test(){
> 	const int a;
<snip>

Good question.  Should it be legal to declare a const without a value?

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on the 'group where everyone may benefit.