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[dev.typeparams] cmd/compile: avoid ir.DeepCopy in noder.constDecl

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Instead of using ir.DeepCopy to copy the IR from the previous constant
declaration, just call exprList again and then fix up the position
information. This is equivalent in practice, but has cleaner semantics
for tricky corner cases like constant declarations that contain
function literals.

In particular, this refactoring is necessary for the next CL that
cleans up function literal construction, because it adds extra
consistency checks that weren't satisfied by DeepCopy'd OCLOSUREs.

Change-Id: I0372bde5d6613695ee572cc8bf8fb4ff9aef4cb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/327449
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Matthew Dempsky 2021-06-11 18:51:56 -07:00
parent 2954f11ead
commit 8f00eb0099
1 changed files with 11 additions and 6 deletions
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17
src/cmd/compile/internal/noder/noder.go
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@ -450,7 +450,7 @@ func (p *noder) varDecl(decl *syntax.VarDecl) []ir.Node {
type constState struct {
group *syntax.Group
typ ir.Ntype
values []ir.Node
values syntax.Expr
iota int64
}
@ -468,16 +468,15 @@ func (p *noder) constDecl(decl *syntax.ConstDecl, cs *constState) []ir.Node {
names := p.declNames(ir.OLITERAL, decl.NameList)
typ := p.typeExprOrNil(decl.Type)
var values []ir.Node
if decl.Values != nil {
values = p.exprList(decl.Values)
cs.typ, cs.values = typ, values
cs.typ, cs.values = typ, decl.Values
} else {
if typ != nil {
base.Errorf("const declaration cannot have type without expression")
}
typ, values = cs.typ, cs.values
typ = cs.typ
}
values := p.exprList(cs.values)
nn := make([]ir.Node, 0, len(names))
for i, n := range names {
@ -485,10 +484,16 @@ func (p *noder) constDecl(decl *syntax.ConstDecl, cs *constState) []ir.Node {
base.Errorf("missing value in const declaration")
break
}
v := values[i]
if decl.Values == nil {
v = ir.DeepCopy(n.Pos(), v)
ir.Visit(v, func(v ir.Node) {
if ir.HasUniquePos(v) {
v.SetPos(n.Pos())
}
})
}
typecheck.Declare(n, typecheck.DeclContext)
n.Ntype = typ