cmd/compile: fix nongeneric closures in generic functions

Ensure that formal parameter Names are correctly copied and marked
with the correct Curfn. We need to ensure this even when the underlying
closure has no type parameters.

(Aside: it is strange that the types of things contain formal
parameter names that need to be copied. Maybe that's an underlying
larger problem that needs to be fixed.)

Fixes #45738

Change-Id: Ia13d69eea992ff7080bd44065115bc52eb624e73
Reviewed-on: https://go-review.googlesource.com/c/go/+/313652
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>

diff --git a/src/cmd/compile/internal/escape/escape.go b/src/cmd/compile/internal/escape/escape.go
index b706d7d2c8cd1ce722430b712262e5dbdc76be7a..05bd44c35de5e58a52069bb3a637f54f52c27197 100644 (file)
--- a/src/cmd/compile/internal/escape/escape.go
+++ b/src/cmd/compile/internal/escape/escape.go
@@ -1295,7 +1295,7 @@ func (e *escape) newLoc(n ir.Node, transient bool) *location {
                if n.Op() == ir.ONAME {
                        n := n.(*ir.Name)
                        if n.Curfn != e.curfn {
-                               base.Fatalf("curfn mismatch: %v != %v", n.Curfn, e.curfn)
+                               base.Fatalf("curfn mismatch: %v != %v for %v", n.Curfn, e.curfn, n)
                        }
 
                        if n.Opt != nil {
@@ -1308,6 +1308,9 @@ func (e *escape) newLoc(n ir.Node, transient bool) *location {
 }
 
 func (b *batch) oldLoc(n *ir.Name) *location {
+       if n.Canonical().Opt == nil {
+               base.Fatalf("%v has no location", n)
+       }
        return n.Canonical().Opt.(*location)
 }
 

diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index d60f0af548f11680e6ef1c047d056b0cab3eb922..3ebc8dff6d84322d2d5c2379e9497a87ebb1d73b 100644 (file)
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -667,7 +667,10 @@ func instTypeName(name string, targs []*types.Type) string {
 // result is t; otherwise the result is a new type. It deals with recursive types
 // by using TFORW types and finding partially or fully created types via sym.Def.
 func (subst *subster) typ(t *types.Type) *types.Type {
-       if !t.HasTParam() {
+       if !t.HasTParam() && t.Kind() != types.TFUNC {
+               // Note: function types need to be copied regardless, as the
+               // types of closures may contain declarations that need
+               // to be copied. See #45738.
                return t
        }
 

diff --git a/test/typeparam/issue45738.go b/test/typeparam/issue45738.go
new file mode 100644 (file)
index 0000000..9f03e79
--- /dev/null
+++ b/test/typeparam/issue45738.go
@@ -0,0 +1,18 @@
+// compile -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 main
+
+//go:noinline
+func f[T any]() {
+       x := 5
+       g := func() int { return x }
+       g()
+}
+
+func main() {
+       f[int]()
+}