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discard """
cmd: "nim check --warningAsError:StrictNotNil $file"
action: "compile"
"""
import tables
{.experimental: "strictNotNil".}
type
Nilable* = ref object
a*: int
field*: Nilable
NonNilable* = Nilable not nil
Nilable2* = nil NonNilable
# proc `[]`(a: Nilable, b: int): Nilable =
# nil
# Nilable tests
# # test and
proc testAnd(a: Nilable) =
echo not a.isNil and a.a > 0 # ok
# test else branch and inferring not isNil
# proc testElse(a: Nilable, b: int) =
# if a.isNil:
# echo 0
# else:
# echo a.a
# test that here we can infer that n can't be nil anymore
proc testNotNilAfterAssign(a: Nilable, b: int) =
var n = a # a: MaybeNil n: MaybeNil
if n.isNil: # n: Safe a: MaybeNil
n = Nilable() # n: Safe a: MaybeNil
echo n.a # ok
proc callVar(a: var Nilable) =
a = nil
proc testVarAlias(a: Nilable) = # a: 0 aliasA: 1 {0} {1}
var aliasA = a # {0, 1} 0 MaybeNil 1 MaybeNil
if not a.isNil: # {0, 1} 0 Safe 1 Safe
callVar(aliasA) # {0, 1} 0 MaybeNil 1 MaybeNil
# if aliasA stops being in alias: it might be nil, but then a is still not nil
# if not: it cant be nil as it still points here
echo a.a # ok
proc testAliasCheck(a: Nilable) =
var aliasA = a
if not a.isNil:
echo aliasA.a # ok
proc testFieldCheck(a: Nilable) =
if not a.isNil and not a.field.isNil:
echo a.field.a # ok
proc testTrackField =
var a = Nilable(field: Nilable())
echo a.field.a # ok
proc testNonNilDeref(a: NonNilable) =
echo a.a # ok
# # not only calls: we can use partitions for dependencies for field aliases
# # so we can detect on change what does this affect or was this mutated between us and the original field
# proc testUniqueHashTree(a: Nilable): Nilable =
# # TODO what would be a clash
# var field = 0
# if not a.isNil and not a.field.isNil:
# # echo a.field.a
# echo a[field].a
# result = Nilable()
proc testSeparateShadowingResult(a: Nilable): Nilable =
result = Nilable()
if not a.isNil:
var result: Nilable = nil
echo result.a
proc testNonNilCString(a: cstring not nil) =
echo a[0] # ok
proc testNonNilPtr(a: ptr int not nil) =
echo a[] # ok
# proc testTryCatchDetectNoRaise(a: Nilable) =
# var other = Nilable()
# try:
# other = nil
# other = a
# other = Nilable()
# except:
# other = nil
# echo other.a # ok
# proc testTryCatchDetectFinally =
# var other = Nilable()
# try:
# other = nil
# other = Nilable()
# except:
# other = Nilable()
# finally:
# other = nil
# echo other.a # can't deref other: it is nil
# proc testTryCatchDetectNilableWithRaise(b: bool) =
# var other = Nilable()
# try:
# if b:
# other = nil
# else:
# other = Nilable()
# var other2 = raiseCall()
# except:
# echo other.a # ok
# echo other.a # can't deref a: it might be nil
proc testRaise(a: Nilable) =
if a.isNil:
raise newException(ValueError, "a == nil")
echo a.a # ok
# proc testBlockScope(a: Nilable) =
# var other = a
# block:
# var other = Nilable()
# echo other.a # ok
# echo other.a # can't deref other: it might be nil
# # (ask Araq about this: not supported yet) ok we can't really get the nil value from here, so should be ok
# proc testDirectRaiseCall: NonNilable =
# var a = raiseCall()
# result = NonNilable()
proc testStmtList =
var a = Nilable()
block:
a = nil
a = Nilable()
echo a.a # ok
proc testItemDerefNoWarning(a: var seq[Nilable]) =
a[0] = Nilable() # good: now .. if we dont track, how do we know
echo a[0].a # ok
var b = 1
const c = 0
a[c] = Nilable()
echo a[0].a # ok
# proc callChange(a: Nilable) =
# a.field = nil
# proc testCallAlias =
# var a = Nilable(field: Nilable())
# callChange(a)
# echo a.field.a # can't deref a.field, it might be nil
# # proc test10(a: Nilable) =
# # if not a.isNil and not a.b.isNil:
# # c_memset(globalA.addr, 0, globalA.sizeOf.csize_t)
# # globalA = nil
# # echo a.a # can't deref a: it might be nil
var nilable: Nilable
var withField = Nilable(a: 0, field: Nilable())
|