go/printer: parenthesize type in <-((<-chan int)(nil))
When printing synthetic syntax (not created by the parser),
the tree for <-((<-chan int)(nil)) without any ParenExpr nodes
was misprinted so that it was parsed back as a receive of
a receive. This changes emits parens around the channel type.
Fixes #63362
Change-Id: I2041ced224f0bca001cee5d37f7a127265d21020
Reviewed-on: https://go-review.googlesource.com/c/go/+/532556
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@google.com>