cmd/compile: fix corner case in DWARF inline info generation

The helper routine for returning pre-inlining parameter declarations
wasn't properly handling the case where you have more than one
parameter named "_" in a function signature; this triggered a map
collision later on when the function was inlined and DWARF was
generated for the inlined routine instance.

Fixes #23179.

Change-Id: I12e5d6556ec5ce08e982a6b53666a4dcc1d22201
Reviewed-on: https://go-review.googlesource.com/84755
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index 07e4f9d2e9e6fd2bc5a791d2590326941bca3393..d3834ddc379910a077213fcc084c0a835aa7adad 100644 (file)
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -599,7 +599,9 @@ func preInliningDcls(fnsym *obj.LSym) []*Node {
        }
        for _, n := range dcl {
                c := n.Sym.Name[0]
-               if c == '.' || n.Type.IsUntyped() {
+               // Avoid reporting "_" parameters, since if there are more tham
+               // one, it can result in a collision later on, as in #23179.
+               if unversion(n.Sym.Name) == "_" || c == '.' || n.Type.IsUntyped() {
                        continue
                }
                rdcl = append(rdcl, n)

diff --git a/test/fixedbugs/issue23179.dir/a.go b/test/fixedbugs/issue23179.dir/a.go
new file mode 100644 (file)
index 0000000..1b79666
--- /dev/null
+++ b/test/fixedbugs/issue23179.dir/a.go
@@ -0,0 +1,9 @@
+// Copyright 2017 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
+
+func F(x int, _ int, _ bool) int {
+       return x
+}

diff --git a/test/fixedbugs/issue23179.dir/b.go b/test/fixedbugs/issue23179.dir/b.go
new file mode 100644 (file)
index 0000000..edf5e6d
--- /dev/null
+++ b/test/fixedbugs/issue23179.dir/b.go
@@ -0,0 +1,11 @@
+// Copyright 2017 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 b
+
+import "a"
+
+func G(x int) int {
+       return a.F(x, 1, false)
+}

diff --git a/test/fixedbugs/issue23179.go b/test/fixedbugs/issue23179.go
new file mode 100644 (file)
index 0000000..8000a52
--- /dev/null
+++ b/test/fixedbugs/issue23179.go
@@ -0,0 +1,7 @@
+// compiledir
+
+// Copyright 2017 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