From 1a708bcf1d17171056a42ec1597ca8848c854d2a Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Thu, 9 Sep 2021 14:42:42 -0700 Subject: [PATCH] cmd/compile: don't crash while reporting invalid alias cycle Add a missing nil check in the formatting code for expression nodes. Matches the nil checks in the same code. Fixes #48301. Change-Id: Ia9bfd3535254a94996ee190b544d95e15433d252 Reviewed-on: https://go-review.googlesource.com/c/go/+/348740 Trust: Robert Griesemer Reviewed-by: Matthew Dempsky --- src/cmd/compile/internal/ir/fmt.go | 2 +- test/fixedbugs/issue48301.go | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) create mode 100644 test/fixedbugs/issue48301.go diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go index d19fe453ef..22fbf39975 100644 --- a/src/cmd/compile/internal/ir/fmt.go +++ b/src/cmd/compile/internal/ir/fmt.go @@ -559,7 +559,7 @@ func exprFmt(n Node, s fmt.State, prec int) { } nprec := OpPrec[n.Op()] - if n.Op() == OTYPE && n.Type().IsPtr() { + if n.Op() == OTYPE && n.Type() != nil && n.Type().IsPtr() { nprec = OpPrec[ODEREF] } diff --git a/test/fixedbugs/issue48301.go b/test/fixedbugs/issue48301.go new file mode 100644 index 0000000000..46fe779a42 --- /dev/null +++ b/test/fixedbugs/issue48301.go @@ -0,0 +1,13 @@ +// errorcheck -G=0 + +// 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. + +// Don't crash while reporting the error. + +package p + +func _() { + type T = T // ERROR "T uses T" +} -- 2.48.1