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digitalmars.D.learn - DIP-1000 and return

reply =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
The code


auto asStatic(T, size_t length)(T[length] arr)
{
     return arr;
}

 safe pure nothrow  nogc unittest
{
     auto x = [1, 2, 3].asStatic;
     static assert(is(typeof(x) == int[x.length]));
     static assert(is(typeof([1, 2, 3].asStatic) == 
int[x.length]));
}


now fails on Git master (after DIP-1000 has been merged) as


array_ex.d(55,6): Error: parameter arr is 'return' but function 
does not return any indirections
array_ex.d(63,23): Error: template instance 
array_ex.asStatic!(int, 3LU) error instantiating
array_ex.d(64,5): Error: static assert  (is(typeof(x) == 
int[x.length])) is false


I tried qualifying argument with `return ref` as described at

https://wiki.dlang.org/DIP25

but that fails because parameter must be allowed to be an r-value 
aswell.

Any clues?
Jan 01 2017
next sibling parent reply Stefan Koch <uplink.coder googlemail.com> writes:
On Sunday, 1 January 2017 at 17:41:46 UTC, Nordlöw wrote:

 The code


 auto asStatic(T, size_t length)(T[length] arr)
 {
     return arr;
 }

  safe pure nothrow  nogc unittest
 {
     auto x = [1, 2, 3].asStatic;
     static assert(is(typeof(x) == int[x.length]));
     static assert(is(typeof([1, 2, 3].asStatic) == 
 int[x.length]));
 }


 now fails on Git master (after DIP-1000 has been merged) as


 array_ex.d(55,6): Error: parameter arr is 'return' but function 
 does not return any indirections
 array_ex.d(63,23): Error: template instance 
 array_ex.asStatic!(int, 3LU) error instantiating
 array_ex.d(64,5): Error: static assert  (is(typeof(x) == 
 int[x.length])) is false


 I tried qualifying argument with `return ref` as described at

 https://wiki.dlang.org/DIP25

 but that fails because parameter must be allowed to be an 
 r-value aswell.

 Any clues?



Try:
  auto asStatic(T, size_t length)(scope T[length] arr)
  {
      return arr;
  }
Jan 01 2017
next sibling parent =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
On Sunday, 1 January 2017 at 18:00:54 UTC, Stefan Koch wrote:

 Try:
  auto asStatic(T, size_t length)(scope T[length] arr)
  {
      return arr;
  }


Fails as

array_ex.d(72,10): Error: parameter arr is 'return' but function 
does not return any indirections
array_ex.d(80,27): Error: template instance 
array_ex.asStatic!(int, 3LU) error instantiating
array_ex.d(81,9): Error: static assert  (is(typeof(x) == 
int[x.length])) is false
Jan 01 2017
prev sibling parent reply =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
On Sunday, 1 January 2017 at 18:00:54 UTC, Stefan Koch wrote:


 Try:
  auto asStatic(T, size_t length)(scope T[length] arr)
  {
      return arr;
  }


I've tried as many combinations of `return` and `scope` as I can 
think of such as

     T[length] asStatic(T, size_t length)(return scope T[length] 
arr)
     {
         return arr;
     }

but all complain about the same thing

Error: parameter arr is 'return' but function does not return any 
indirections

It seems like compiler incorrectly infers that `arr` must be 
`return` despite it doesn't have any indirections (because it's a 
static array).

Walter?
Jan 02 2017
parent reply =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
On Monday, 2 January 2017 at 14:38:53 UTC, Nordlöw wrote:

 I've tried as many combinations of `return` and `scope` as I 
 can think of such as


Update:

Qualifying `asStatic` with ` safe pure nothrow  nogc` as

T[length] asStatic(T, size_t length)(T[length] arr)
      safe pure nothrow  nogc
{
     return arr;
}

makes

 safe pure nothrow  nogc unittest
{
     auto x = [1, 2, 3].asStatic;
     static assert(is(typeof(x) == int[x.length]));
     static assert(is(typeof([1, 2, 3].asStatic) == 
int[x.length]));
}

compile. Also

T[length] asStatic(T, size_t length)(scope T[length] arr)
      safe pure nothrow  nogc
{
     return arr;
}

works. Is with or without `scope` preferred here?

Seems to be some problem with template qualifier inference. 
Should I file a bug report?
Jan 02 2017
parent Ilya Yaroshenko <ilyayaroshenko gmail.com> writes:
On Monday, 2 January 2017 at 15:28:57 UTC, Nordlöw wrote:


 Should I file a bug report?


Yes please
Mar 08 2017
prev sibling parent =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:
On Sunday, 1 January 2017 at 17:41:46 UTC, Nordlöw wrote:

 now fails on Git master (after DIP-1000 has been merged) as


When compiled with `-transition=safe`, that is.
Jan 01 2017