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Compiler: Closure iterators: Handle comma in multi-exception except variant #25922

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Compiler: Closure iterators: Handle comma in multi-exception except variant #25922

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2f56348
Compiler: Closure iterators: Handle comma in multi-exception `except`…
moigagoo Jun 17, 2026
85befdc
Compiler: Closure iterators: Handle comma in multi-exception `except`…
moigagoo Jun 17, 2026
fcaad41
Tests: Closure iterators: Add test for but #25921.
moigagoo Jun 17, 2026
5360c3d
Tests: Closure iterators: Do not run test for bug #25921 on JS backend.
moigagoo Jun 17, 2026
ee3fb6a
Tests: Closure iterators: Add fallback for JS backend.
moigagoo Jun 17, 2026
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5 changes: 5 additions & 0 deletions compiler/closureiters.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -335,6 +335,11 @@ proc collectExceptState(ctx: var Ctx, n: PNode): PNode {.inline.} =
if c.len > 1:
var cond: PNode = nil
for i in 0..<c.len - 1:
# `nkStmtList` means we hit a comma in a `FirstException, SecondException` expression.
# We skip it and go to the next child, which must be a `nkType` representing the next expection.
if c[i].kind == nkStmtList:
continue

@Araq Araq Jun 17, 2026

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Makes no sense. The structure is supposed to be except-guard-A, except-guard-B, ..., [last] nkStmtList

@moigagoo moigagoo Jun 18, 2026

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Sorry, this really is a silly take 😕 Somehow I thought that RangeDefect, Exception is traversed as nkType, nkStmtList, nkType, which is wrong, of course. I should have slept at this time of night probably instead of making blind guesses and spending CI cycles and your time.

In the PNode the nkExceptBranch that represents except RangeDefect, Exception looks like this:

except RangeDefect,
        ...   :tmpSlLower0 = Exception:
        ...   complete(retFutParamSym_603979901, result)
        ...   return nil

I.e. Exception is not represented as nkType at all, while it is a type. Maybe the problem is with PNode construction that happens earlier.

The structure is supposed to be except-guard-A, except-guard-B, ..., [last] nkStmtList

Yeah, matching each exception type individually works, no problem here. The problem is I can't match multiple exceptions in one except branch.

AFAIK matching multiple exception types is allowed and valid in except branches, so this should work.


assert(c[i].kind == nkType)
let nextCond = newTreeIT(nkCall, c.info, ctx.g.getSysType(c.info, tyBool),
newSymNode(g.getSysMagic(c.info, "of", mOf)),
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21 changes: 21 additions & 0 deletions tests/iter/tclosureiters.nim
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Expand Up @@ -31,6 +31,7 @@ discard """
(3, 1)
(3, 2)
(3, 3)
32
'''
"""

Expand Down Expand Up @@ -174,3 +175,23 @@ iterator pairs(): (int, int) {.closure.} =

for pair in pairs():
echo pair

# bug #25921
when not defined(js):
import asyncdispatch

proc getNumber(): Future[int] {.async, raises: [RangeDefect, Exception].} =
32

proc getX(): Future[int] {.async.} =
let x =
try:
await getNumber()
except RangeDefect, Exception:
return

x

echo waitFor getX()
else:
echo 32
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