net: only build cgo_stub.go on unix or wasip1

We were building it for Windows, although Windows code never calls
any of these functions. When using -tags netgo that cause a multiple
definition of cgoAvailable.

Fixes #61153

Change-Id: Ib9e1de7720a8c0dacd6f12002917bf305dfa5405
Reviewed-on: https://go-review.googlesource.com/c/go/+/507655
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

diff --git a/src/net/cgo_stub.go b/src/net/cgo_stub.go
index a8514c19f8faee32749cbdac343eae95352e137b..b26b11af8b4dcd156627d033128d6b527ad22fd0 100644 (file)
--- a/src/net/cgo_stub.go
+++ b/src/net/cgo_stub.go
@@ -3,13 +3,13 @@
 // license that can be found in the LICENSE file.
 
 // This file holds stub versions of the cgo functions called on Unix systems.
-// We build this file if using the netgo build tag, or if cgo is not
-// enabled and we are using a Unix system other than Darwin, or if it's
-// wasip1 where cgo is never available.
-// Darwin is exempted because it always provides the cgo routines,
-// in cgo_unix_syscall.go.
+// We build this file:
+// - if using the netgo build tag on a Unix system
+// - on a Unix system without the cgo resolver functions
+//   (Darwin always provides the cgo functions, in cgo_unix_syscall.go)
+// - on wasip1, where cgo is never available
 
-//go:build netgo || (!cgo && unix && !darwin) || wasip1
+//go:build (netgo && unix) || (unix && !cgo && !darwin) || wasip1
 
 package net