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discard """
output: '''12
empty
he, no return type;
abc a string
ha'''
"""
proc ReturnT[T](x: T): T =
when T is void:
echo "he, no return type;"
else:
result = x & " a string"
proc nothing(x, y: void): void =
echo "ha"
proc callProc[T](p: proc (x: T) {.nimcall.}, x: T) =
when T is void:
p()
else:
p(x)
proc intProc(x: int) =
echo x
proc emptyProc() =
echo "empty"
callProc[int](intProc, 12)
callProc[void](emptyProc)
ReturnT[void]()
echo ReturnT[string]("abc")
nothing()
block: # typeof(stmt)
proc fn1(): auto =
discard
proc fn2(): auto =
1
doAssert type(fn1()) is void
doAssert typeof(fn1()) is void
doAssert typeof(fn1()) isnot int
doAssert type(fn2()) isnot void
doAssert typeof(fn2()) isnot void
when typeof(fn1()) is void: discard
else: doAssert false
doAssert typeof(1+1) is int
doAssert typeof((discard)) is void
type A1 = typeof(fn1())
doAssert A1 is void
type A2 = type(fn1())
doAssert A2 is void
doAssert A2 is A1
when false:
# xxx: MCS/UFCS doesn't work here: Error: expression 'fn1()' has no type (or is ambiguous)
type A3 = fn1().type
proc bar[T](a: T): string = $T
doAssert bar(1) == "int"
doAssert bar(fn1()) == "void"
proc bar2[T](a: T): bool = T is void
doAssert not bar2(1)
doAssert bar2(fn1())
block:
proc bar3[T](a: T): T = a
let a1 = bar3(1)
doAssert compiles(block:
let a1 = bar3(fn2()))
doAssert not compiles(block:
let a2 = bar3(fn1()))
doAssert compiles(block: bar3(fn1()))
doAssert compiles(bar3(fn1()))
doAssert typeof(bar3(fn1())) is void
doAssert not compiles(sizeof(bar3(fn1())))
block:
var a = 1
doAssert typeof((a = 2)) is void
doAssert typeof((a = 2; a = 3)) is void
doAssert typeof(block:
a = 2; a = 3) is void
block:
var a = 1
template bad1 = echo (a; a = 2)
doAssert not compiles(bad1())
block:
template bad2 = echo (nonexistent; discard)
doAssert not compiles(bad2())
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