cmd/compile: ensure generic function is loaded when it needs to be re-exported

In the case where we need to re-export a generic function/method from
another package in the export data of the current package, make sure it
is loaded before trying to write it out.

Fixed #49667

Change-Id: I177754bb762689f34cf5c8ad246d43f1cdbbf195
Reviewed-on: https://go-review.googlesource.com/c/go/+/365837
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

4 files changed, 41 insertions, 0 deletions

diff --git a/test/typeparam/issue49667.dir/a.go b/test/typeparam/issue49667.dir/a.go
new file mode 100644
index 0000000000..3b1889f699
--- /dev/null
+++ b/test/typeparam/issue49667.dir/a.go
@@ -0,0 +1,12 @@
+// 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 a
+
+type A[T any] struct {
+}
+
+func (a A[T]) F() {
+	_ = a
+}
diff --git a/test/typeparam/issue49667.dir/b.go b/test/typeparam/issue49667.dir/b.go
new file mode 100644
index 0000000000..e7f781e4af
--- /dev/null
+++ b/test/typeparam/issue49667.dir/b.go
@@ -0,0 +1,11 @@
+// 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 b
+
+import "a"
+
+type B[T any] struct {
+	_ a.A[T]
+}
diff --git a/test/typeparam/issue49667.dir/main.go b/test/typeparam/issue49667.dir/main.go
new file mode 100644
index 0000000000..fccefe023f
--- /dev/null
+++ b/test/typeparam/issue49667.dir/main.go
@@ -0,0 +1,11 @@
+// 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 "b"
+
+func main() {
+	var _ b.B[int]
+}
diff --git a/test/typeparam/issue49667.go b/test/typeparam/issue49667.go
new file mode 100644
index 0000000000..76930e5e4f
--- /dev/null
+++ b/test/typeparam/issue49667.go
@@ -0,0 +1,7 @@
+// rundir -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 ignored