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https://github.com/nim-lang/Nim.git
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4058801607
* spec for view types * spec additions * refactoring; there are two different kinds of views * refactorings and spec additions * enforce that view types are initialized * enforce borrowing from the first formal parameter * enforce lifetimes for borrowing of locals * typo in the manual * clarify in the implementation what a borrow operation really is
24 lines
546 B
Nim
24 lines
546 B
Nim
discard """
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errormsg: "cannot borrow"
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nimout: '''tcannot_borrow.nim(21, 7) Error: cannot borrow meh; what it borrows from is potentially mutated
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tcannot_borrow.nim(22, 3) the mutation is here'''
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line: 21
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"""
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{.experimental: "views".}
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type
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Foo = object
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field: string
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proc valid(s: var seq[Foo]) =
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let v: lent Foo = s[0] # begin of borrow
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echo v.field # end of borrow
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s.setLen 0 # valid because 'v' isn't used afterwards
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proc dangerous(s: var seq[Foo]) =
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let meh: lent Foo = s[0]
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s.setLen 0
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echo meh.field
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