1 files changed, 59 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47818.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47818.go2
new file mode 100644
index 0000000000..5334695b5e
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47818.go2
@@ -0,0 +1,59 @@
+// 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.
+
+// Parser accepts type parameters but the type checker
+// needs to report any operations that are not permitted
+// before Go 1.18.
+
+package go1_17
+
+type T[P /* ERROR type parameters require go1\.18 or later */ any] struct{}
+
+// for init (and main, but we're not in package main) we should only get one error
+func init[P /* ERROR func init must have no type parameters */ any]()   {}
+func main[P /* ERROR type parameters require go1\.18 or later */ any]() {}
+
+func f[P /* ERROR type parameters require go1\.18 or later */ any](x P) {
+	var _ T[ /* ERROR type instantiation requires go1\.18 or later */ int]
+	var _ (T[ /* ERROR type instantiation requires go1\.18 or later */ int])
+	_ = T[ /* ERROR type instantiation requires go1\.18 or later */ int]{}
+	_ = T[ /* ERROR type instantiation requires go1\.18 or later */ int](struct{}{})
+}
+
+func (T[ /* ERROR type instantiation requires go1\.18 or later */ P]) g(x int) {
+	f[ /* ERROR function instantiation requires go1\.18 or later */ int](0)     // explicit instantiation
+	(f[ /* ERROR function instantiation requires go1\.18 or later */ int])(0)   // parentheses (different code path)
+	f( /* ERROR implicit function instantiation requires go1\.18 or later */ x) // implicit instantiation
+}
+
+type C1 interface {
+	comparable // ERROR undeclared name: comparable \(requires version go1\.18 or later\)
+}
+
+type C2 interface {
+	comparable // ERROR undeclared name: comparable \(requires version go1\.18 or later\)
+	int        // ERROR embedding non-interface type int requires go1\.18 or later
+	~ /* ERROR embedding interface element ~int requires go1\.18 or later */ int
+	int /* ERROR embedding interface element int\|~string requires go1\.18 or later */ | ~string
+}
+
+type _ interface {
+	// errors for these were reported with their declaration
+	C1
+	C2
+}
+
+type (
+	_ comparable // ERROR undeclared name: comparable \(requires version go1\.18 or later\)
+	// errors for these were reported with their declaration
+	_ C1
+	_ C2
+
+	_ = comparable // ERROR undeclared name: comparable \(requires version go1\.18 or later\)
+	// errors for these were reported with their declaration
+	_ = C1
+	_ = C2
+)
+
+// TODO(gri) need test cases for imported constraint types (see also issue #47967)
+\ No newline at end of file