runtime: testprogcgo: don't call exported Go functions directly from Go

Instead route through a C function, to avoid declaration conflicts
between the declaration needed in the cgo comment and the declaration
generated by cgo in _cgo_export.h.

This is not something user code will ever do, so no need to make it
work in cgo.

Fixes #46502

Change-Id: I1bfffdc76ef8ea63e3829871298d0774157957a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/327309
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>

src/runtime/testdata/testprogcgo/aprof.go

@@ -10,7 +10,7 @@ package main
 // The test fails when the function is the first C function.
 // The exported functions are the first C functions, so we use that.
 
-// extern void GoNop();
+// extern void CallGoNop();
 import "C"
 
 import (
@@ -38,7 +38,7 @@ func CgoCCodeSIGPROF() {
 					break
 				}
 			}
-			C.GoNop()
+			C.CallGoNop()
 		}
 		c <- true
 	}()

src/runtime/testdata/testprogcgo/aprof_c.c

@@ -0,0 +1,9 @@
+// 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.
+
+#include "_cgo_export.h"
+
+void CallGoNop() {
+	GoNop();
+}

src/runtime/testdata/testprogcgo/bigstack1_windows.c

@@ -0,0 +1,12 @@
+// 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.
+
+// This is not in bigstack_windows.c because it needs to be part of
+// testprogcgo but is not part of the DLL built from bigstack_windows.c.
+
+#include "_cgo_export.h"
+
+void CallGoBigStack1(char* p) {
+	goBigStack1(p);
+}

src/runtime/testdata/testprogcgo/bigstack_windows.go

@@ -6,7 +6,7 @@ package main
 
 /*
 typedef void callback(char*);
-extern void goBigStack1(char*);
+extern void CallGoBigStack1(char*);
 extern void bigStack(callback*);
 */
 import "C"
@@ -18,7 +18,7 @@ func init() {
 func BigStack() {
 	// Create a large thread stack and call back into Go to test
 	// if Go correctly determines the stack bounds.
-	C.bigStack((*C.callback)(C.goBigStack1))
+	C.bigStack((*C.callback)(C.CallGoBigStack1))
 }
 
 //export goBigStack1