From: Robert Griesemer <gri@golang.org>
Date: Fri, 20 Aug 2021 04:35:57 +0000 (-0700)
Subject: go/types: don't override x.mode before using it
X-Git-Tag: go1.18beta1~1687
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=e17439e0877d6ddb6881d9eb59758c27cc62f930;p=gostls13.git

go/types: don't override x.mode before using it

Changing the mode of x before using the old value is clearly wrong.
And x is not needed anymore afterward so besides being misplaced,
the assignment is not needed in the first place.

Tested manually as it's a bit complicated to set up a test.

Needs to be back-ported to 1.17.

Fixes #47777.

Change-Id: I06f1fa9443eb98009b4276f566d557fd52f1d6d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/343809
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/go/types/call.go b/src/go/types/call.go
index 390e9cd892..08ef2451bf 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -223,7 +223,6 @@ func (check *Checker) exprList(elist []ast.Expr, allowCommaOk bool) (xlist []*op
 		// exactly one (possibly invalid or comma-ok) value
 		xlist = []*operand{&x}
 		if allowCommaOk && (x.mode == mapindex || x.mode == commaok || x.mode == commaerr) {
-			x.mode = value
 			x2 := &operand{mode: value, expr: e, typ: Typ[UntypedBool]}
 			if x.mode == commaerr {
 				x2.typ = universeError