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Illegal capture of closure iterator, when should be legal
proc foo() =
iterator it() {.closure.} =
discard
proc useIter() {.nimcall.} =
var iii = it # <-- illegal capture
useIter()
foo()
nim c test
.../test.nim(5, 15) Error: illegal capture 'it' because 'useIter' has the calling convention: <nimcall>
This capture should be legal as it is a fresh local instance of the iterator.
nim --version
Nim Compiler Version 1.7.1 [Linux: amd64]
Compiled at 2022-08-03
Copyright (c) 2006-2022 by Andreas Rumpf
git hash: 0d734d7966644018207a20cf23f16912f9c276d8
active boot switches: -d:release
This capture should be legal as it is a fresh local instance of the iterator.
If this is true, this shall be a regression since 1.4.0 , https://github.com/nim-lang/Nim/commit/b022576ce96f5c166c7f5684bef9de682704cb1b looks suspicious, I'm looking into it.
is this true? tests\closure\tinvalidclosure4.nim exists ensure it's a illegal capture
But tinvalidclosure4.nim demonstrates a case when a nimcall function tries to capture outer variable, which is technically impossible and thus illegal. In my example it doesn't capture anything and so should be possible to instantiate from within a nimcall function. Something like in the following valid code:
proc foo() =
proc bar() = # Local function, but not a closure, because no captures
echo "hi"
proc baz() {.nimcall.} = # Calls local function
bar()
baz()
foo()
I believe this is because closure iterators are always treated as closures internally in nim, even if they don't capture anything, but I could be wrong.
