mirror of
https://github.com/nim-lang/Nim.git
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ecf9efa397
* document general use of `_`, error message, fixes fixes #20687, fixes #21435 Documentation and changelog updated to clarify new universal behavior of `_`. Also new error message for attempting to use `_`, new tests, and fixes with overloadable symbols and implicit generics. * add test for #21435
123 lines
2.4 KiB
Nim
123 lines
2.4 KiB
Nim
discard """
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targets: "c cpp js"
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"""
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import std/[assertions, sequtils]
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proc test() =
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block:
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proc ok(_, _, a: int): int =
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doAssert not compiles(_)
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a
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doassert ok(4, 2, 5) == 5
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block:
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proc ok(_: int, _: int, a: int): int = a
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doAssert ok(4, 2, 5) == 5
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block:
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proc ok(_: int, _: float, a: int): int = a
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doAssert ok(1, 2.0, 5) == 5
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block:
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proc ok(_: int, _: float, _: string, a: int): int = a
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doAssert ok(1, 2.6, "5", 5) == 5
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block:
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proc ok[T](_, _, a: T): T =
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doAssert not compiles(_)
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a
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doAssert ok(4, 2, 5) == 5
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doAssert ok("a", "b", "c") == "c"
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doAssert not compiles(ok(1, 2, "a"))
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block:
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let ok = proc (_, _, a: int): int =
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doAssert not compiles(_)
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a
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doAssert ok(4, 2, 5) == 5
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block:
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proc foo(lam: proc (_, _, a: int): int): int =
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lam(4, 2, 5)
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doAssert foo(proc (_, _, a: auto): auto =
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doAssert not compiles(_)
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a) == 5
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block:
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iterator fn(_, _: int, c: int): int = yield c
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doAssert toSeq(fn(1,2,3)) == @[3]
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block:
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template ok(_, _, a: int): int = a
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doAssert ok(4, 2, 5) == 5
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block:
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doAssert not (compiles do:
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template bad(_: int): int = _
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discard bad(3))
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block:
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template ok(_: int, _: int, a: int): int = a
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doAssert ok(4, 2, 5) == 5
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block:
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template ok(_: int, _: float, a: int): int = a
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doAssert ok(1, 2.0, 5) == 5
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block:
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template ok(_: int, _: float, _: string, a: int): int = a
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doAssert ok(1, 2.6, "5", 5) == 5
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block:
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template main2() =
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iterator fn(_, _: int, c: int): int = yield c
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main2()
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block:
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template main =
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proc foo(_: int) =
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let a = _
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doAssert not compiles(main())
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block: # generic params
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doAssert not (compiles do:
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proc foo[_](t: typedesc[_]): seq[_] = @[default(_)]
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doAssert foo[int]() == 0)
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block:
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proc foo[_, _](): int = 123
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doAssert foo[int, bool]() == 123
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block:
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proc foo[T; U](_: typedesc[T]; _: typedesc[U]): (T, U) = (default(T), default(U))
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doAssert foo(int, bool) == (0, false)
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proc closureTest() =
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var x = 0
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block:
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proc foo(_, _: int) = x += 5
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foo(1, 2)
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doAssert x == 5
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block:
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proc foo(_: int, _: float) = x += 5
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foo(1, 2)
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doAssert x == 10
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block:
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proc foo(_: int, _: float, _: string) = x += 5
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foo(1, 2, "5")
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doAssert x == 15
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static: test()
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test()
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when not defined(js):
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static: closureTest()
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closureTest()
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