[dev.typealias] go/types: implement type aliases

Now a TypeName is just that: a name for a type (not just Named and Basic types
as before). If it happens to be an alias, its type won't be a Named or Basic type,
or it won't have the same name. We can determine this externally.

It may be useful to provide a helper predicate to make that test easily accessible,
but we can get to that if there's an actual need.

The field/method lookup code has become more general an simpler, which is a good sign.
The changes in methodset.go are symmetric to the changes in lookup.go.

Known issue: Cycles created via alias types are not properly detected at the moment.

For #18130.

Change-Id: I90a3206be13116f89c221b5ab4d0f577eec6c78a
Reviewed-on: https://go-review.googlesource.com/35091
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index f844575269..24b3365717 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -68,11 +68,11 @@ var tests = [][]string{
 	{"testdata/decls1.src"},
 	{"testdata/decls2a.src", "testdata/decls2b.src"},
 	{"testdata/decls3.src"},
+	{"testdata/decls4.src"},
 	{"testdata/const0.src"},
 	{"testdata/const1.src"},
 	{"testdata/constdecl.src"},
 	{"testdata/vardecl.src"},
-	//{"testdata/aliasdecl.src"},
 	{"testdata/expr0.src"},
 	{"testdata/expr1.src"},
 	{"testdata/expr2.src"},