[release-branch.go1.17] cmd/compile: fix case where init info of OAS node is dropped

When an OAS node is converted to an OSELRECV2 node in tcSelect(), the
possible DCL node in the Init field was being dropped, since a
completely new node was being created and the Init field was not set. I
don't expect n.Init() to be set for the ORECV case, but the code now
deals with that too.

Fixed bug in both tcSelect() and transformSelect().

Cherry-picked from https://go-review.googlesource.com/c/go/+/348569

Fixes #49511

Change-Id: Id5b736daa8e90afda88aaa3769dde801db294c0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/363664
Trust: Dan Scales <danscales@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

diff --git a/src/cmd/compile/internal/noder/transform.go b/src/cmd/compile/internal/noder/transform.go
index 2859089e69b91386010db02268764a66aa2de7aa..1a0c4d94c7e3f594a87578a0cb557054b6e88b08 100644 (file)
--- a/src/cmd/compile/internal/noder/transform.go
+++ b/src/cmd/compile/internal/noder/transform.go
@@ -495,10 +495,11 @@ func transformSelect(sel *ir.SelectStmt) {
                if ncase.Comm != nil {
                        n := ncase.Comm
                        oselrecv2 := func(dst, recv ir.Node, def bool) {
-                               n := ir.NewAssignListStmt(n.Pos(), ir.OSELRECV2, []ir.Node{dst, ir.BlankNode}, []ir.Node{recv})
-                               n.Def = def
-                               n.SetTypecheck(1)
-                               ncase.Comm = n
+                               selrecv := ir.NewAssignListStmt(n.Pos(), ir.OSELRECV2, []ir.Node{dst, ir.BlankNode}, []ir.Node{recv})
+                               selrecv.Def = def
+                               selrecv.SetTypecheck(1)
+                               selrecv.SetInit(n.Init())
+                               ncase.Comm = selrecv
                        }
                        switch n.Op() {
                        case ir.OAS:

diff --git a/src/cmd/compile/internal/typecheck/stmt.go b/src/cmd/compile/internal/typecheck/stmt.go
index 922a01bfbe9aa7d6dea6ab34e03e5955ef883105..2fc6d04e854786eaef02223c18d2a40c11c6fea2 100644 (file)
--- a/src/cmd/compile/internal/typecheck/stmt.go
+++ b/src/cmd/compile/internal/typecheck/stmt.go
@@ -383,10 +383,11 @@ func tcSelect(sel *ir.SelectStmt) {
                        n := Stmt(ncase.Comm)
                        ncase.Comm = n
                        oselrecv2 := func(dst, recv ir.Node, def bool) {
-                               n := ir.NewAssignListStmt(n.Pos(), ir.OSELRECV2, []ir.Node{dst, ir.BlankNode}, []ir.Node{recv})
-                               n.Def = def
-                               n.SetTypecheck(1)
-                               ncase.Comm = n
+                               selrecv := ir.NewAssignListStmt(n.Pos(), ir.OSELRECV2, []ir.Node{dst, ir.BlankNode}, []ir.Node{recv})
+                               selrecv.Def = def
+                               selrecv.SetTypecheck(1)
+                               selrecv.SetInit(n.Init())
+                               ncase.Comm = selrecv
                        }
                        switch n.Op() {
                        default:

diff --git a/test/fixedbugs/issue48289.go b/test/fixedbugs/issue48289.go
new file mode 100644 (file)
index 0000000..94dbeee
--- /dev/null
+++ b/test/fixedbugs/issue48289.go
@@ -0,0 +1,28 @@
+// run
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func main() {
+       ch := make(chan int, 1)
+
+       var ptrs [2]*int
+       for i := range ptrs {
+               ch <- i
+               select {
+               case x := <-ch:
+                       ptrs[i] = &x
+               }
+       }
+
+       for i, ptr := range ptrs {
+               if *ptr != i {
+                       panic(fmt.Sprintf("got *ptr %d, want %d", *ptr, i))
+               }
+       }
+}