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fixes #24806; generates =wasMoved for seqs self-assignment to reset the buffer #24830

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fixes #24806; generates =wasMoved for seqs self-assignment to reset the buffer #24830

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14 changes: 8 additions & 6 deletions compiler/liftdestructors.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -575,12 +575,14 @@ proc forallElements(c: var TLiftCtx; t: PType; body, x, y: PNode) =
body.sons.setLen counterIdx

proc checkSelfAssignment(c: var TLiftCtx; t: PType; body, x, y: PNode) =
let addrX = newTreeIT(nkAddr, c.info, makePtrType(c.fn, x.typ, c.idgen), x)
let addrY = newTreeIT(nkAddr, c.info, makePtrType(c.fn, y.typ, c.idgen), y)
var cond = callCodegenProc(c.g, "sameSeqPayload", c.info,
newTreeIT(nkAddr, c.info, makePtrType(c.fn, x.typ, c.idgen), x),
newTreeIT(nkAddr, c.info, makePtrType(c.fn, y.typ, c.idgen), y)
addrX, addrY
)
cond.typ() = getSysType(c.g, c.info, tyBool)
body.add genIf(c, cond, newTreeI(nkReturnStmt, c.info, newNodeI(nkEmpty, c.info)))
body.add genIf(c, cond,
genBuiltin(c, mWasMoved, "`=wasMoved`", addrX))

proc fillSeqOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
case c.kind
Expand All @@ -590,10 +592,10 @@ proc fillSeqOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
of attachedAsgn, attachedDeepCopy:
# we generate:
# if x.p == y.p:
# return
# setLen(dest, y.len)
# wasMoved(x)
# setLen(x, y.len)
# var i = 0
# while i < y.len: dest[i] = y[i]; inc(i)
# while i < y.len: x[i] = y[i]; inc(i)
# This is usually more efficient than a destroy/create pair.
checkSelfAssignment(c, t, body, x, y)
body.add setLenSeqCall(c, t, x, y)
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48 changes: 48 additions & 0 deletions tests/arc/tmalloc.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -14,3 +14,51 @@ block: # bug #22058
V(v: foo())

doAssert bar().v == @[byte(0)]

type
GlobFilter* = object
incl*: bool
glob*: string

GlobState* = object
one: int
two: int

proc aa() =
let filters = @[GlobFilter(incl: true, glob: "**")]
var wbg = newSeqOfCap[GlobState](1)
wbg.add GlobState()
var
dirc = @[wbg]
while true:
wbg = dirc[^1]
dirc.add wbg
break

var handlerLocs = newSeq[string]()
handlerLocs.add "sammich"
aa()
aa()

block: # bug #24806
block:
proc aa() =
var
a = @[0]
b = @[a]
block:
a = b[0]
b.add a

aa()

block:
proc aa() =
var
a = @[0]
b = @[a]
block:
a = b[^1]
b.add a

aa()