libgo: update to Go1.18beta2

gotools/
	* Makefile.am (go_cmd_cgo_files): Add ast_go118.go
	(check-go-tool): Copy golang.org/x/tools directories.
	* Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/384695

1 files changed, 18 insertions, 0 deletions

diff --git a/libgo/go/math/big/rat_test.go b/libgo/go/math/big/rat_test.go
index 02569c1..d98c89b 100644
--- a/libgo/go/math/big/rat_test.go
+++ b/libgo/go/math/big/rat_test.go
@@ -726,3 +726,21 @@ func TestIssue34919(t *testing.T) {
 		}
 	}
 }
+
+func TestDenomRace(t *testing.T) {
+	x := NewRat(1, 2)
+	const N = 3
+	c := make(chan bool, N)
+	for i := 0; i < N; i++ {
+		go func() {
+			// Denom (also used by Float.SetRat) used to mutate x unnecessarily,
+			// provoking race reports when run in the race detector.
+			x.Denom()
+			new(Float).SetRat(x)
+			c <- true
+		}()
+	}
+	for i := 0; i < N; i++ {
+		<-c
+	}
+}