[dev.typeparams] cmd/compile/internal/types2: add Config.AllowTypeLists to control type list handling

Eventually the flag should not be set anymore, but we set it in the
compiler until all tests have been converted.

Also, convert some more types2 tests to use the type set notation.

Change-Id: I616599a3473451ab75d67272016b2bd3de6835af
Reviewed-on: https://go-review.googlesource.com/c/go/+/324571
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/types2/testdata/examples/constraints.go2 b/src/cmd/compile/internal/types2/testdata/examples/constraints.go2
index efefaa2a25..d9805fe694 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/constraints.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/constraints.go2
@@ -7,6 +7,18 @@
 package p
 
 type (
+	// Type lists are processed as unions but an error is reported.
+	// TODO(gri) remove this once the parser doesn't accept type lists anymore.
+	_ interface{
+		type /* ERROR use generalized embedding syntax instead of a type list */ int
+	}
+	_ interface{
+		type /* ERROR use generalized embedding syntax instead of a type list */ int
+		type float32
+	}
+)
+
+type (
 	// Arbitrary types may be embedded like interfaces.
 	_ interface{int}
 	_ interface{~int}