cmd/compile/internal/importer: key tparams by Package instead of pkgname

The importer type param index used package name type parameter key,
causing type parameters to be reused/overwritten if two packages in the
import graph had the same combination of (name, declaration name, type
parameter name).

Fix this by instead using the *Package in the key.

Fixes #51836

Change-Id: I881ceaf3cf7c1ab4e0835962350feb552e79b233
Reviewed-on: https://go-review.googlesource.com/c/go/+/394219
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

4 files changed, 39 insertions, 0 deletions

diff --git a/test/typeparam/issue51836.dir/a.go b/test/typeparam/issue51836.dir/a.go
new file mode 100644
index 00000000000..e9223c9aa82
--- /dev/null
+++ b/test/typeparam/issue51836.dir/a.go
@@ -0,0 +1,8 @@
+// Copyright 2022 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 a
+
+type T[K any] struct {
+}
diff --git a/test/typeparam/issue51836.dir/aa.go b/test/typeparam/issue51836.dir/aa.go
new file mode 100644
index 00000000000..d774be282e5
--- /dev/null
+++ b/test/typeparam/issue51836.dir/aa.go
@@ -0,0 +1,13 @@
+// Copyright 2022 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 a
+
+import (
+	"./a"
+)
+
+type T[K any] struct {
+	t a.T[K]
+}
diff --git a/test/typeparam/issue51836.dir/p.go b/test/typeparam/issue51836.dir/p.go
new file mode 100644
index 00000000000..98197ae0fd9
--- /dev/null
+++ b/test/typeparam/issue51836.dir/p.go
@@ -0,0 +1,11 @@
+// Copyright 2022 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 (
+	a "./aa"
+)
+
+var Foo a.T[int]
diff --git a/test/typeparam/issue51836.go b/test/typeparam/issue51836.go
new file mode 100644
index 00000000000..c755e74b9cd
--- /dev/null
+++ b/test/typeparam/issue51836.go
@@ -0,0 +1,7 @@
+// compiledir -s
+
+// Copyright 2022 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 ignored