cmd/compile: fix ICE in reporting of invalid recursive types

asNode(t.Nod).Name.Param will be nil for builtin types (i.e., the
universal predeclared types and unsafe.Pointer). These types can't be
part of a cycle anyway, so we can just skip them.

Fixes #42075.

Change-Id: Ic7a44de65c6bfd16936545dee25e36de8850acf3
Reviewed-on: https://go-review.googlesource.com/c/go/+/263717
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

1 files changed, 16 insertions, 0 deletions

diff --git a/test/fixedbugs/issue42075.go b/test/fixedbugs/issue42075.go
new file mode 100644
index 0000000000..af85fb281d
--- /dev/null
+++ b/test/fixedbugs/issue42075.go
@@ -0,0 +1,16 @@
+// errorcheck
+
+// Copyright 2020 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 p
+
+import "unsafe"
+
+type T struct { // ERROR "recursive type"
+	x int
+	p unsafe.Pointer
+
+	f T
+}