cmd/compile: don't use dictionary convert to shaped empty interface

Fixes: golang#53254 Change-Id: I3153d6ebb9f25957b09363f45c5cd4651ee84c2d Reviewed-on: https://go-review.googlesource.com/c/go/+/410655 Reviewed-by: Matthew Dempsky <[email protected]> Run-TryBot: Wayne Zuo <[email protected]> TryBot-Result: Gopher Robot <[email protected]> Reviewed-by: Keith Randall <[email protected]> Reviewed-by: Keith Randall <[email protected]>
robertodauria · Jun 22, 2022 · ff17b7d · ff17b7d
1 parent 2a3b467
commit ff17b7d
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Showing 2 changed files with 21 additions and 2 deletions.
diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
@@ -1349,7 +1349,7 @@ func (g *genInst) dictPass(info *instInfo) {
 			mce := m.(*ir.ConvExpr)
 			// Note: x's argument is still typed as a type parameter.
 			// m's argument now has an instantiated type.
-			if mce.X.Type().HasShape() || m.Type().HasShape() {
+			if mce.X.Type().HasShape() || (m.Type().HasShape() && !m.Type().IsEmptyInterface()) {
 				m = convertUsingDictionary(info, info.dictParam, m.Pos(), mce.X, m, m.Type())
 			}
 		case ir.ODOTTYPE, ir.ODOTTYPE2:
@@ -1446,7 +1446,7 @@ func findDictType(info *instInfo, t *types.Type) int {
 // instantiated node of the CONVIFACE node or XDOT node (for a bound method call) that is causing the
 // conversion.
 func convertUsingDictionary(info *instInfo, dictParam *ir.Name, pos src.XPos, v ir.Node, in ir.Node, dst *types.Type) ir.Node {
-	assert(v.Type().HasShape() || in.Type().HasShape())
+	assert(v.Type().HasShape() || (in.Type().HasShape() && !in.Type().IsEmptyInterface()))
 	assert(dst.IsInterface())
 
 	if v.Type().IsInterface() {

diff --git a/test/typeparam/issue53254.go b/test/typeparam/issue53254.go
@@ -0,0 +1,19 @@
+// compile
+
+// Copyright 2022 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
+
+type Interface[T any] interface {
+}
+
+func F[T any]() Interface[T] {
+	var i int
+	return i
+}
+
+func main() {
+	F[int]()
+}