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fixes #19013 [backport:1.6] (#19111)

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* fixes #19013 [backport:1.6]

* added test case
This commit is contained in:
Andreas Rumpf 2021-11-09 12:43:16 +01:00 • committed by GitHub
commit b7c66ce860
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4 changed files with 46 additions and 8 deletions
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17
compiler/isolation_check.nim
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@ -77,6 +77,17 @@ proc canAlias*(arg, ret: PType): bool =
var marker = initIntSet()
result = canAlias(arg, ret, marker)
proc containsVariable(n: PNode): bool =
case n.kind
of nodesToIgnoreSet:
result = false
of nkSym:
result = n.sym.kind in {skForVar, skParam, skVar, skLet, skConst, skResult, skTemp}
else:
for ch in n:
if containsVariable(ch): return true
result = false
proc checkIsolate*(n: PNode): bool =
if types.containsTyRef(n.typ):
# XXX Maybe require that 'n.typ' is acyclic. This is not much
@ -96,7 +107,11 @@ proc checkIsolate*(n: PNode): bool =
else:
let argType = n[i].typ
if argType != nil and not isCompileTimeOnly(argType) and containsTyRef(argType):
if argType.canAlias(n.typ):
if argType.canAlias(n.typ) or containsVariable(n[i]):
# bug #19013: Alias information is not enough, we need to check for potential
# "overlaps". I claim the problem can only happen by reading again from a location
# that materialized which is only possible if a variable that contains a `ref`
# is involved.
return false
result = true
of nkIfStmt, nkIfExpr: