cmd/compile: use AutogeneratedPos for method value wrapper

We use AutogeneratedPos for most compiler-generated functions. But
for method value wrappers we currently don't. Instead, we use the
Pos for their (direct) declaration if there is one, otherwise
not set it in methodValueWrapper, which will probably cause it to
inherit from the caller, i.e. the Pos of that method value
expression. If that Pos has inline information, it will cause the
method wrapper to have bogus inline information, which could lead
to infinite loop when printing a stack trace.

Change it to use AutogeneratedPos instead.

Fixes #51401.

Change-Id: I398dfe85f9f875e1fd82dc2f489dab63ada6570d
Reviewed-on: https://go-review.googlesource.com/c/go/+/388794
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

diff --git a/src/cmd/compile/internal/walk/closure.go b/src/cmd/compile/internal/walk/closure.go
index 68e16803be088f97d7d7db956abec7368bd35e9b..f7bd2e0e073e212a038bd93b2094d81d707dbdbb 100644 (file)
--- a/src/cmd/compile/internal/walk/closure.go
+++ b/src/cmd/compile/internal/walk/closure.go
@@ -235,15 +235,7 @@ func methodValueWrapper(dot *ir.SelectorExpr) *ir.Name {
        saveLineNo := base.Pos
        ir.CurFunc = nil
 
-       // Set line number equal to the line number where the method is declared.
-       if pos := dot.Selection.Pos; pos.IsKnown() {
-               base.Pos = pos
-       }
-       // Note: !dot.Selection.Pos.IsKnown() happens for method expressions where
-       // the method is implicitly declared. The Error method of the
-       // built-in error type is one such method.  We leave the line
-       // number at the use of the method expression in this
-       // case. See issue 29389.
+       base.Pos = base.AutogeneratedPos
 
        tfn := ir.NewFuncType(base.Pos, nil,
                typecheck.NewFuncParams(t0.Params(), true),

diff --git a/test/fixedbugs/issue51401.go b/test/fixedbugs/issue51401.go
new file mode 100644 (file)
index 0000000..1e8e0d0
--- /dev/null
+++ b/test/fixedbugs/issue51401.go
@@ -0,0 +1,44 @@
+// run
+
+// 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.
+
+// Issue 51401: bad inline info in generated interface method wrapper
+// causes infinite loop in stack unwinding.
+
+package main
+
+import "runtime"
+
+type Outer interface{ Inner }
+
+type impl struct{}
+
+func New() Outer { return &impl{} }
+
+type Inner interface {
+       DoStuff() error
+}
+
+func (a *impl) DoStuff() error {
+       return newError()
+}
+
+func newError() error {
+       stack := make([]uintptr, 50)
+       runtime.Callers(2, stack[:])
+
+       return nil
+}
+
+func main() {
+       funcs := listFuncs(New())
+       for _, f := range funcs {
+               f()
+       }
+}
+
+func listFuncs(outer Outer) []func() error {
+       return []func() error{outer.DoStuff}
+}