https://github.com/nim-lang/Nim/pull/20614
I am able to reproduce with:
nim c -r --warning:ProveField:on /tmp/test.nim
Run
Yes that is odd. I'm not sure why the warning triggers in the loop but not
above. FWIW I can get the warning to go away with:
for node in list:
let n = node[]
case
I'm on version 1.6.8 I can try updating
anyway if I run `nim c -r --forceBuild --verbosity\:0 --hint\[Processing\]\:off
--excessiveStackTrace\:on test.nim`
or even just `nim c test.nim`
it compiles without warning and outputs
foo
hello
Run
if I run with `nim c -
I do not see a warning when compiled with:
nim c -r --forceBuild --verbosity\:0 --hint\[Processing\]\:off
--excessiveStackTrace\:on /tmp/test.nim
Run
I also tried it with the `--warning:ProveField:on` flag, still no warning.
My nim version:
Nim Compiler
not sure if I got the issue right. If the problem is related to partial
initialization, why it affects also accessors?
e.g.
# node is correctly initialized with all fields
let n = Node(kind: nkChild, name: "foo")
case n.kind
of nkChild: echo $n.name #using case statement
This is unfortunate but happens because you are initializing a `ref` object
which allows unsafe partial initialization, making a `NodeObj` first errors the
way it should without adding any warning flags:
type
NodeKind = enum
nkParent,
nkChild
Node
the problem seems to happen inside loops:
let list = @[Node(kind: nkParent), Node(kind: nkChild)]
for node in list:
case node.kind
of nkParent:
node.children = @[] # inside the loop results in warning, if not in a
loop is fine as in previous post
of
ok, this is working:
let a = Node(kind: nkParent)
case a.kind
of nkParent:
a.children = @[]
else: discard
Run
I guess it makes sense as the kind could change at runtime so the compiler
needs a case or if to infer it.
Still on a more complex code I ha
sorry if the code is not too clean, when I do
let a = Node(kind: nkParent, children: @[]) # this is fine (now warnings)
echo $a.children # this throws a warning (cannot prove that field is
accessible)
Run
Myabe I am missing something, but was expecting that once `a
`--warning[ProveField]:on` works but depending on your shell you can also write
it as `--warning:ProveField:on`
cool, I have 2 questions/issues though:
1\. I was able to enable the warning using a pragma like
`{.warning[ProveField]: on.} ` on top of the file, but not sure how to pass it
as a compilation argument. I tried nim c or nimble build with that argument and
it says `no matches found: --warning[Pr
And yeah, this should have become the default for Nim v2 but v2 is already late
and overwhelming.
Use `--warning[ProveField]:on`.
Given a simple "kinded" object like:
type
NodeKind = enum
nkParent,
nkChild
Node = ref NodeObj
NodeObj {.acyclic.} = object
case kind: NodeKind
of nkParent:
children: seq[Node]
of nkChild:
name: strin
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