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go/misc/cgo/testplugin/testdata/issue44956/main.go
Cherry Zhang 7a1e963058 cmd/compile, cmd/link: dynamically export writable static tmps
Static tmps are private to a package, but with plugins a package
can be shared among multiple DSOs. They need to have a consistent
view of the static tmps, especially for writable ones. So export
them. (Read-only static tmps have the same values anyway, so it
doesn't matter. Also Mach-O doesn't support dynamically exporting
read-only symbols anyway.)

Fixes #44956.

Change-Id: I921e25b7ab73cd5d5347800eccdb7931e3448779
Reviewed-on: https://go-review.googlesource.com/c/go/+/301793
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
2021-03-16 23:14:54 +00:00

48 lines
1.1 KiB
Go

// 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.
// Issue 44956: writable static temp is not exported correctly.
// In the test below, package base is
//
// X = &map{...}
//
// which compiles to
//
// X = &stmp // static
// stmp = makemap(...) // in init function
//
// plugin1 and plugin2 both import base. plugin1 doesn't use
// base.X, so that symbol is deadcoded in plugin1.
//
// plugin1 is loaded first. base.init runs at that point, which
// initialize base.stmp.
//
// plugin2 is then loaded. base.init already ran, so it doesn't run
// again. When base.stmp is not exported, plugin2's base.X points to
// its own private base.stmp, which is not initialized, fail.
package main
import "plugin"
func main() {
_, err := plugin.Open("issue44956p1.so")
if err != nil {
panic("FAIL")
}
p2, err := plugin.Open("issue44956p2.so")
if err != nil {
panic("FAIL")
}
f, err := p2.Lookup("F")
if err != nil {
panic("FAIL")
}
x := f.(func() *map[int]int)()
if x == nil || (*x)[123] != 456 {
panic("FAIL")
}
}