IndexError when use a list of funcs generated bymapit

[foldl]

Use mapit to generate a list of functions. When calling these functions, Index error occur.

Example

import sequtils, sugar
static:
  # following map & mapit should be equivalent
  echo [1, 2].map((it) => func (x: int): int = it + x).map((f) => f(100))
  echo [1, 2].mapit(func (x: int): int = it + x).map((f) => f(100))

Current Output

@[101, 102]
fatal.nim(39)            sysFatal
Error: unhandled exception: index 23 not in 0 .. 2 [IndexError]

Expected Output

@[101, 102]
@[101, 102]

Possible Solution

N/A.

Additional Information

N/A

$ nim -v
Nim Compiler Version 1.0.2 [Windows: amd64]
Compiled at 2019-10-22
Copyright (c) 2006-2019 by Andreas Rumpf

git hash: 193b3c66bbeffafaebff166d24b9866f1eaaac0e
active boot switches: -d:release

[narimiran]

Regarding the expected output, running the example outside of the static block gives:

@[101, 102]
@[102, 102]

[foldl]

Here is an example that can't give the correct result running in isMainModule.
It seems like that only m[1] is used in mapIt.

if isMainModule:
  let m = @[func (x: int): int = x + 100, func (x: int): int = x + 200]
  let l = m.mapIt(func (x: int): int = it(x))
  echo l.mapIt(it 1)

Current Output

@[201, 201]

Expected Output

@[101, 201]

[alehander92]

hm, is if isMainModule valid , i thought one can only when

[narimiran]

hm, is if isMainModule valid , i thought one can only when

It doesn't matter, I originally reproduced the problem without it.

[foldl]

My finding: it is not captured by the generated proc of mapIt, but defined as
a global variable.

So, the title of this issue should be changed to: {.inject} is not handled properly when
generating closure?

if isMainModule:
  let m = @[func (x: int): int = x + 100, func (x: int): int = x + 200]
  # The "simplified" generated C code of this line is listed below
  let l = m.mapIt(func (x: int): int = it(x))  
  echo l.mapIt(it 1)

The "simplified" generated C code:

it__MpefkJ9cQAwQD9aL17D5DVvw; // *it* is a global variable, which is wrong!
N_LIB_PRIVATE N_NIMCALL(NI, colonanonymous___vsp4xqNMQqR9b4HAKLhepJw_3)(NI x) {	NI result;
	result = it__MpefkJ9cQAwQD9aL17D5DVvw(x);
	return result;
}

// let l = m.mapIt(func (x: int): int = it(x))
for (int i = 0; i < 2; i++)
{
    it__MpefkJ9cQAwQD9aL17D5DVvw = m[i];
    l[i].proc = colonanonymous___vsp4xqNMQqR9b4HAKLhepJw_3;
    l[i].env = NIL;
}

[foldl]

Some updates on this issue.

Further checking indicates that the root cause is, in a for (or while) loop, env is owned by the proc, so it is initialized out of for. The generated func-s in the loop are all referring to the env by ref, so they are all referencing to the same env, which is modified in each iteration of for.
(This has nothing to do with {.inject.})

@Araq pointed out in this thread:

That's actually what the spec says needs to be done (but I'm not sure it's written down somewhere in the manual. sigh). Reason: Performance, JS interop. Workaround: use system.closureScope instead.

Unfortunately, this workaround does not work for this case. In the proc generated by closureScope, asgnRef is used, failing to capture the local variable correctly.