cmd/compile: prevent typecheck importer reading type parameter twice

This is a port of CL 349009 to typecheck importer.

Fixes #48306

Change-Id: Iec3f078089346bd85f0ab739896e079940325011
Reviewed-on: https://go-review.googlesource.com/c/go/+/349011
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>

diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 8bc098c2bdaab06cccfd8696e82f66427c9a7270..6eec94a98499a6ec998bc3104dc1f5e7f11ed3c4 100644 (file)
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -316,16 +316,12 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
                return n
 
        case 'T', 'U':
-               var rparams []*types.Type
-               if tag == 'U' {
-                       rparams = r.typeList()
-               }
-
                // Types can be recursive. We need to setup a stub
                // declaration before recursing.
                n := importtype(pos, sym)
                t := n.Type()
                if tag == 'U' {
+                       rparams := r.typeList()
                        t.SetRParams(rparams)
                }
 

diff --git a/src/go/internal/gcimporter/gcimporter_test.go b/src/go/internal/gcimporter/gcimporter_test.go
index 478534daf2e129ae981a899da3dc9c8395ba31f8..9f4345d8f9c06463c288d9afb37901fbdc1fd388 100644 (file)
--- a/src/go/internal/gcimporter/gcimporter_test.go
+++ b/src/go/internal/gcimporter/gcimporter_test.go
@@ -167,8 +167,6 @@ func TestImportTypeparamTests(t *testing.T) {
        skip := map[string]string{
                "equal.go":  "inconsistent embedded sorting", // TODO(rfindley): investigate this.
                "nested.go": "fails to compile",              // TODO(rfindley): investigate this.
-
-               "issue46461.go": "known issue with type parameter constraints referring back to parameterized type",
        }
 
        for _, entry := range list {

diff --git a/test/run.go b/test/run.go
index d2b7b88768a3167d724dc3906b9240217ec308c2..790b54bfd2c2185eb74f3e6e5c2eaee666944621 100644 (file)
--- a/test/run.go
+++ b/test/run.go
@@ -2188,8 +2188,6 @@ var g3Failures = setOf(
 
        "typeparam/nested.go", // -G=3 doesn't support function-local types with generics
 
-       "typeparam/issue46461b.go", // -G=3 fails when type parameters refer back to the parameterized type itself
-
        "typeparam/mdempsky/4.go", // -G=3 can't export functions with labeled breaks in loops
 )
 

diff --git a/test/typeparam/issue48306.dir/a.go b/test/typeparam/issue48306.dir/a.go
new file mode 100644 (file)
index 0000000..739750b
--- /dev/null
+++ b/test/typeparam/issue48306.dir/a.go
@@ -0,0 +1,9 @@
+// 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 I[T I[T]] interface {
+       F() T
+}

diff --git a/test/typeparam/issue48306.dir/main.go b/test/typeparam/issue48306.dir/main.go
new file mode 100644 (file)
index 0000000..5d602fe
--- /dev/null
+++ b/test/typeparam/issue48306.dir/main.go
@@ -0,0 +1,15 @@
+// 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 "a"
+
+type S struct{}
+
+func (*S) F() *S { return nil }
+
+func main() {
+       var _ a.I[*S] = &S{}
+}

diff --git a/test/typeparam/issue48306.go b/test/typeparam/issue48306.go
new file mode 100644 (file)
index 0000000..76930e5
--- /dev/null
+++ b/test/typeparam/issue48306.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