cmd/compile: fix missing case for shape double-check function

Missing case types.TUNSAFEPTR in parameterizedBy().

Also realized there was the same missing case in the type substituter
(*Tsubster).Typ().

Fixes #48103

Change-Id: If71f1a6ef80932f0e2120d4c18b39a30189fd8fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/346669
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/test/typeparam/issue48013.go b/test/typeparam/issue48013.go
new file mode 100644
index 0000000000..179d9f44e9
--- /dev/null
+++ b/test/typeparam/issue48013.go
@@ -0,0 +1,39 @@
+// run -gcflags=-G=3
+
+// 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.
+
+package main
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+type S[T any] struct {
+	val T
+}
+
+// Test type substitution where base type is unsafe.Pointer
+type U[T any] unsafe.Pointer
+
+func test[T any]() T {
+	var q U[T]
+	var v struct {
+		// Test derived type that contains an unsafe.Pointer
+		p   unsafe.Pointer
+		val T
+	}
+	_ = q
+	return v.val
+}
+
+func main() {
+	want := 0
+	got := test[int]()
+	if got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+
+}