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digitalmars.D.learn - Why this fails when using unittest?

reply Machine Code <jckj33 gmail.com> writes:
outside an unittest, this compiles fine:

	struct A
	{
		enum A foo = "hehe";
		this(string a) { m_a = a; }
		alias m_a this;
		string m_a;
	}

but if you wrap this a unittest {} and compile with

 dmd -unittest -run foo.d


this give the following error:


 cannot implicitly convert expression "hehe" of type string to A


Why does inside a unittest it doesn't work? the constructor 
this(string) {} seems to get disabled.
Jun 06 2019
next sibling parent Machine Code <jckj33 gmail.com> writes:
On Thursday, 6 June 2019 at 17:40:17 UTC, Machine Code wrote:

 outside an unittest, this compiles fine:

 	struct A
 	{
 		enum A foo = "hehe";
 		this(string a) { m_a = a; }
 		alias m_a this;
 		string m_a;
 	}

 but if you wrap this a unittest {} and compile with

 dmd -unittest -run foo.d


 this give the following error:


 cannot implicitly convert expression "hehe" of type string to A


 Why does inside a unittest it doesn't work? the constructor 
 this(string) {} seems to get disabled.


I this notice albeit a simple cast workaround that:


 enum A foo = cast(A)"hehe";


or better:


 enum foo = A("hehe");


but isn't that a bug? what am I missing?
Jun 06 2019
prev sibling parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Thursday, 6 June 2019 at 17:40:17 UTC, Machine Code wrote:

 outside an unittest, this compiles fine:

 	struct A


try making it `static struct` instead



 cannot implicitly convert expression "hehe" of type string to A


 Why does inside a unittest it doesn't work? the constructor 
 this(string) {} seems to get disabled.


My suspicion is it is trying to access the context of the 
unittest as a hidden paramater to that constructor there... and 
in an enum, it can't, just stupid compiler didn't think to 
mention the hidden arg here.

my guess.
Jun 06 2019
next sibling parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
On 6/6/19 1:49 PM, Adam D. Ruppe wrote:

 On Thursday, 6 June 2019 at 17:40:17 UTC, Machine Code wrote:

 outside an unittest, this compiles fine:

     struct A


 
 try making it `static struct` instead
 
 

 cannot implicitly convert expression "hehe" of type string to A


 Why does inside a unittest it doesn't work? the constructor 
 this(string) {} seems to get disabled.


 
 My suspicion is it is trying to access the context of the unittest as a 
 hidden paramater to that constructor there... and in an enum, it can't, 
 just stupid compiler didn't think to mention the hidden arg here.
 
 my guess.


Yes, correct guess. A unittest block is actually a function, so it's 
considered an inner struct with a hidden context pointer.

-Steve
Jun 06 2019
parent reply Machine Code <jckj33 gmail.com> writes:
On Thursday, 6 June 2019 at 21:02:37 UTC, Steven Schveighoffer 
wrote:

 On 6/6/19 1:49 PM, Adam D. Ruppe wrote:

 On Thursday, 6 June 2019 at 17:40:17 UTC, Machine Code wrote:

 outside an unittest, this compiles fine:

     struct A


 
 try making it `static struct` instead
 
 

 cannot implicitly convert expression "hehe" of type string 
 to A


 Why does inside a unittest it doesn't work? the constructor 
 this(string) {} seems to get disabled.


 
 My suspicion is it is trying to access the context of the 
 unittest as a hidden paramater to that constructor there... 
 and in an enum, it can't, just stupid compiler didn't think to 
 mention the hidden arg here.
 
 my guess.


 Yes, correct guess. A unittest block is actually a function, so 
 it's considered an inner struct with a hidden context pointer.

 -Steve


Intesting, I also tried to declare it inside a function, that did 
not work either. Is this hidden context pointer a current 
limitation in CTFE? I've tried to declare the struct at module 
level and run the functions on static this() to workaround that 
but to finish, I'd like to eble to run the code in static main() 
only when unnitest is enabled but so I haven't manged to do that.

*Imaginary code* would be:

unittest
{
	enum enabled = true;
}
else
{
     enum enabled = true;
}

but I was on my mind unittest was similar to static if() but as 
it's like a function, there are no else let alone acess to enum 
enabled as true, outside the block but the idea is run (or even 
only declare) a piece of code (which includes that struct) only 
if we are an unittest.
Jun 07 2019
parent reply Machine Code <jckj33 gmail.com> writes:
On Friday, 7 June 2019 at 16:30:34 UTC, Machine Code wrote:

 On Thursday, 6 June 2019 at 21:02:37 UTC, Steven Schveighoffer 
 wrote:

 [...]


 Intesting, I also tried to declare it inside a function, that 
 did not work either. Is this hidden context pointer a current 
 limitation in CTFE? I've tried to declare the struct at module 
 level and run the functions on static this() to workaround that 
 but to finish, I'd like to eble to run the code in static 
 main() only when unnitest is enabled but so I haven't manged to 
 do that.

 *Imaginary code* would be:

 unittest
 {
 	enum enabled = true;
 }
 else
 {
     enum enabled = true;
 }

 but I was on my mind unittest was similar to static if() but as 
 it's like a function, there are no else let alone acess to enum 
 enabled as true, outside the block but the idea is run (or even 
 only declare) a piece of code (which includes that struct) only 
 if we are an unittest.


All this effort is because I do not want unittest code in a 
release or even debug. So I want to this be invisible anywhere 
but unittest or at least simulate that wit static if() how I'm 
tring to do
Jun 07 2019
parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Friday, 7 June 2019 at 16:33:13 UTC, Machine Code wrote:

 All this effort is because I do not want unittest code in a 
 release or even debug.


Well, that part is easy:

version(unittest)
struct Foo {}

at any scope is only build when unittests are turned on in this 
build.
Jun 07 2019
parent Machine Code <jckj33 gmail.com> writes:
On Friday, 7 June 2019 at 16:41:12 UTC, Adam D. Ruppe wrote:

 On Friday, 7 June 2019 at 16:33:13 UTC, Machine Code wrote:

 All this effort is because I do not want unittest code in a 
 release or even debug.


 Well, that part is easy:

 version(unittest)
 struct Foo {}

 at any scope is only build when unittests are turned on in this 
 build.


Thank you! I was about to read version docs to see if I could 
determine if I was in unittest by versioning. That's exact 
behavior I was trying to acomplish.

I ended up doing this:

version(unittest)
{
   struct Foo { }
   shared static this() {
     // test code ...
   }
}

Act like a unittest {} but I can use CTFE stuff nicely.

Thank you all guys.
Jun 07 2019
prev sibling parent Machine Code <jckj33 gmail.com> writes:
On Thursday, 6 June 2019 at 17:49:58 UTC, Adam D. Ruppe wrote:

 On Thursday, 6 June 2019 at 17:40:17 UTC, Machine Code wrote:

 outside an unittest, this compiles fine:

 	struct A


 try making it `static struct` instead


didn't work either


 cannot implicitly convert expression "hehe" of type string to 
 A


 Why does inside a unittest it doesn't work? the constructor 
 this(string) {} seems to get disabled.


 My suspicion is it is trying to access the context of the 
 unittest as a hidden paramater to that constructor there... and 
 in an enum, it can't, just stupid compiler didn't think to 
 mention the hidden arg here.

 my guess.


So it's a CTFE limitation in unittest/local functions(I also 
tried to declare that struct inside a function, but did not work 
either). right? assuming it's an error, it's going to be fixed 
anytime soon?
Jun 07 2019