• Elfstone (19/19) Mar 15 2023 ```D
• Elfstone (15/34) Mar 15 2023 Oops, the above code compiles, because I added comments!!!
• Elfstone (5/21) Mar 15 2023 Correction.
• Elfstone (5/32) Mar 15 2023 I can't get it to compile anymore, it must be some mistake from
• Elfstone (4/17) Mar 15 2023 Never mind, I just found out this is supposed to happen, `S` is

Elfstone <elfstone yeah.net> writes:

```D
struct Matrix(S, size_t M, size_t N)
{
}

alias Vec3(S) = Matrix!(S, 3, 1);

void main()
{
     import std.stdio;

     writeln(is(Vec3!float == Matrix!(S, 3, 1), S)); // `alias` 
`S` is defined here
     writeln(is(Matrix!(float, 3, 1) == Matrix!(S, 3, 1), S)); // 
Error: declaration `S` is already defined
}
```

Even though the following code compiles.

```D
     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
```

Elfstone <elfstone yeah.net> writes:

On Thursday, 16 March 2023 at 03:40:04 UTC, Elfstone wrote:
 ```D
 struct Matrix(S, size_t M, size_t N)
 {
 }

 alias Vec3(S) = Matrix!(S, 3, 1);

 void main()
 {
     import std.stdio;

     writeln(is(Vec3!float == Matrix!(S, 3, 1), S)); // `alias` 
 `S` is defined here
     writeln(is(Matrix!(float, 3, 1) == Matrix!(S, 3, 1), S)); 
 // Error: declaration `S` is already defined
 }
 ```

 Even though the following code compiles.

 ```D
     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
 ```

Oops, the above code compiles, because I added comments!!!

Now this really doesn't compile:

```D
struct Matrix(S, size_t M, size_t N)
{
}

alias Vec3(S) = Matrix!(S, 3, 1);

void main()
{
     import std.stdio;

     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
     writeln(is(Matrix!(float, 3, 1) == Matrix!(S, 3, 1), S));
}
```

Elfstone <elfstone yeah.net> writes:

On Thursday, 16 March 2023 at 03:44:19 UTC, Elfstone wrote:
 On Thursday, 16 March 2023 at 03:40:04 UTC, Elfstone wrote:
 [...]

 Oops, the above code compiles, because I added comments!!!

 Now this really doesn't compile:

 ```D
 struct Matrix(S, size_t M, size_t N)
 {
 }

 alias Vec3(S) = Matrix!(S, 3, 1);

 void main()
 {
     import std.stdio;

     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
     writeln(is(Matrix!(float, 3, 1) == Matrix!(S, 3, 1), S));
 }
 ```

Correction.

With or without comments, mostly it doesn't compile, occasionally 
it does!
I have no idea.

Elfstone <elfstone yeah.net> writes:

On Thursday, 16 March 2023 at 04:04:51 UTC, Elfstone wrote:
 On Thursday, 16 March 2023 at 03:44:19 UTC, Elfstone wrote:
 On Thursday, 16 March 2023 at 03:40:04 UTC, Elfstone wrote:
 [...]

 Oops, the above code compiles, because I added comments!!!

 Now this really doesn't compile:

 ```D
 struct Matrix(S, size_t M, size_t N)
 {
 }

 alias Vec3(S) = Matrix!(S, 3, 1);

 void main()
 {
     import std.stdio;

     writeln(is(Vec3!float == Matrix!(S, 3, 1), S));
     writeln(is(Matrix!(float, 3, 1) == Matrix!(S, 3, 1), S));
 }
 ```

 Correction.

 With or without comments, mostly it doesn't compile, 
 occasionally it does!
 I have no idea.

I can't get it to compile anymore, it must be some mistake from 
me. Maybe I forgot to save   while modifying the code.

So the `S` declared in `is` expression can contaminate the scope? 
Is this supposed to happen?

Elfstone <elfstone yeah.net> writes:

On Thursday, 16 March 2023 at 04:31:11 UTC, Elfstone wrote:
 On Thursday, 16 March 2023 at 04:04:51 UTC, Elfstone wrote:
 On Thursday, 16 March 2023 at 03:44:19 UTC, Elfstone wrote:
 [...]

 Correction.

 With or without comments, mostly it doesn't compile, 
 occasionally it does!
 I have no idea.

 I can't get it to compile anymore, it must be some mistake from 
 me. Maybe I forgot to save   while modifying the code.

 So the `S` declared in `is` expression can contaminate the 
 scope? Is this supposed to happen?

Never mind, I just found out this is supposed to happen, `S` is 
supposed to be available later.

https://dlang.org/spec/expression.html#is-parameter-list