cmd/compile: fix irgen mis-handling invalid function declaration

In -G=3 mode, irgen use its own generated IR, which is mis-handling of
bodyless function and declared function with //go:noescape pragma.

Fix this by adopting the same logic in noder.funcDecl, which minor
change in linkname detection.

Fixes #48097

Change-Id: Ibef921c1f75e071ca61685e0cb4543f2ee5efc7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/346470
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/test/fixedbugs/issue48097.go b/test/fixedbugs/issue48097.go
new file mode 100644
index 0000000000..b08c2a2f52
--- /dev/null
+++ b/test/fixedbugs/issue48097.go
@@ -0,0 +1,12 @@
+// errorcheck -complete
+
+// 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 p
+
+func F() // ERROR "missing function body"
+
+//go:noescape
+func f() {} // ERROR "can only use //go:noescape with external func implementations"