[release-branch.go1.11] cmd/compile: don't crash reporting misuse of shadowed built...

The existing implementation causes a compiler panic if a function parameter shadows a built-in function, and then calling that shadowed name.

Updates #27356
Fixes #27399

Change-Id: I1ffb6dc01e63c7f499e5f6f75f77ce2318f35bcd
Reviewed-on: https://go-review.googlesource.com/132876
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 4a095b87d30f1f6f7ae01e966f1af5ee63b15c1c)
Reviewed-on: https://go-review.googlesource.com/c/139103
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go
index 51dd0dba87fcb48580ecadc15228e13c155dd6b7..bf7090518c85123b4ae15ef16434c93c035ca5cb 100644 (file)
--- a/src/cmd/compile/internal/gc/typecheck.go
+++ b/src/cmd/compile/internal/gc/typecheck.go
@@ -1263,7 +1263,7 @@ func typecheck1(n *Node, top int) *Node {
                        n.Op = OCALLFUNC
                        if t.Etype != TFUNC {
                                name := l.String()
-                               if isBuiltinFuncName(name) {
+                               if isBuiltinFuncName(name) && l.Name.Defn != nil {
                                        // be more specific when the function
                                        // name matches a predeclared function
                                        yyerror("cannot call non-function %s (type %v), declared at %s",

diff --git a/test/fixedbugs/issue27356.go b/test/fixedbugs/issue27356.go
new file mode 100644 (file)
index 0000000..4278487
--- /dev/null
+++ b/test/fixedbugs/issue27356.go
@@ -0,0 +1,19 @@
+// errorcheck
+
+// Copyright 2018 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 27356: function parameter hiding built-in function results in compiler crash
+
+package p
+
+var a = []int{1,2,3}
+
+func _(len int) {
+       _ =  len(a) // ERROR "cannot call non-function"
+}
+
+var cap = false
+var _ = cap(a) // ERROR "cannot call non-function"
+