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Using generics in template where instantiate a object with generics got a compile error #10167

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lguzzon opened this Issue Jan 2, 2019 · 3 comments

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lguzzon commented Jan 2, 2019

Using generics in template where instantiate a object with generics got a compile error

Example

type
  Maybe* [T] =  object {. final .}
    case hasValue*: bool
    of true: value*: T
    else: discard


proc Just* [T](aValue: T): Maybe[T] {. inline .} =
  result = Maybe[T](hasValue: true, value: aValue)

template template_Just* [T](aValue: T): Maybe[T] =
  Maybe[T](hasValue: true, value: aValue)

proc Nothing* [T]: Maybe[T] {. inline .} =
  result = Maybe[T](hasValue: false)

echo Just[int](1)
echo template_Just[int](1)

Current Output

Hint: used config file 'C:\Users\a72c\scoop\apps\nim\current\config\nim.cfg' [Conf]
Hint: system [Processing]
Hint: issueTemplateGenerics [Processing]
issueTemplateGenerics.nim(22, 24) template/generic instantiation from here
issueTemplateGenerics.nim(13, 8) Error: cannot instantiate Maybe
got: <int>
but expected: <T>

Code compiled with Nim (nim 0.19.2)

Expected Output

(hasValue: true, value: 1)
(hasValue: true, value: 1)

See here code compiled with Nim (nim 0.16.0)

Possible Solution

Additional Information

@bluenote10

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bluenote10 commented Jan 2, 2019

Duplicate of #5926?

@lguzzon

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lguzzon commented Jan 2, 2019

Yes!!!
Thanks

@krux02

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krux02 commented Jan 2, 2019

Closing this because it is a duplicate.

@krux02 krux02 closed this Jan 2, 2019

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