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cmd/compile: copy captured dictionary var to local var

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When starting a closure that needs a dictionary, copy the closure
variable to a local variable. This lets child closures capture that
dictionary variable correctly.

This is a better fix for #47684, which does not cause problems
like #47723.

Fixes #47723
Update #47684

Change-Id: Ib5d9ffc68a5142e28daa7d0d75683e7a35508540
Reviewed-on: https://go-review.googlesource.com/c/go/+/343871
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
This commit is contained in:
Keith Randall 2021-08-20 10:19:28 -07:00
parent aeec6dbfe0
commit 8486ced8b0
3 changed files with 38 additions and 5 deletions
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16
src/cmd/compile/internal/noder/stencil.go
View file

@ -1087,13 +1087,25 @@ func (subst *subster) node(n ir.Node) ir.Node {
ir.FinishCaptureNames(oldfn.Pos(), saveNewf, newfn)
newfn.ClosureVars = append(newfn.ClosureVars, subst.namelist(oldfn.ClosureVars)...)
// Copy that closure variable to a local one.
// Note: this allows the dictionary to be captured by child closures.
// See issue 47723.
ldict := ir.NewNameAt(x.Pos(), subst.info.gf.Sym().Pkg.Lookup(".dict"))
typed(types.Types[types.TUINTPTR], ldict)
ldict.Class = ir.PAUTO
ldict.Curfn = newfn
newfn.Dcl = append(newfn.Dcl, ldict)
as := ir.NewAssignStmt(x.Pos(), ldict, cdict)
as.SetTypecheck(1)
newfn.Body.Append(as)
// Create inst info for the instantiated closure. The dict
// param is the closure variable for the dictionary of the
// outer function. Since the dictionary is shared, use the
// same entries for startSubDict, dictLen, dictEntryMap.
cinfo := &instInfo{
fun: newfn,
dictParam: cdict,
dictParam: ldict,
gf: subst.info.gf,
gfInfo: subst.info.gfInfo,
startSubDict: subst.info.startSubDict,
@ -1110,7 +1122,7 @@ func (subst *subster) node(n ir.Node) ir.Node {
outerinfo := subst.info
subst.info = cinfo
// Make sure type of closure function is set before doing body.
newfn.Body = subst.list(oldfn.Body)
newfn.Body.Append(subst.list(oldfn.Body)...)
subst.info = outerinfo
subst.newf = saveNewf
ir.CurFunc = saveNewf