test: restore tests for the reject unsafe code option

Tests in test/safe were neglected after moving to the run.go
framework. This change restores them.

These tests are skipped for go/types via -+ option.

Fixes #25668

Change-Id: I8fe26574a76fa7afa8664c467d7c2e6334f1bba9
Reviewed-on: https://go-review.googlesource.com/124660Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

test/safe/nousesafe.go

-// $G $D/pkg.go && pack grc pkg.a pkg.$A 2> /dev/null && rm pkg.$A && errchk $G -I . -u $D/main.go
-// rm -f pkg.a
-
-// Copyright 2012 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 ignored

test/safe/usesafe.go

-// $G $D/pkg.go && pack grcS pkg.a pkg.$A 2> /dev/null && rm pkg.$A && $G -I . -u $D/main.go
-// rm -f pkg.a
-
-// Copyright 2012 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 ignored

test/safe/main.go → test/unsafereject1.go

-// true
+// errorcheck -u -+
 
-// Copyright 2012 The Go Authors. All rights reserved.
+// 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.
 
+// Check that we cannot import a package that uses "unsafe" internally
+// when -u is supplied.
+
 package main
 
-// can't use local path with -u, use -I. instead
-import "pkg"  // ERROR "import unsafe package"
+import "syscall" // ERROR "import unsafe package"
 
 func main() {
-	print(pkg.Float32bits(1.0))
+	print(syscall.Environ())
 }

test/safe/pkg.go → test/unsafereject2.go

-// true
+// errorcheck -u -+
 
-// Copyright 2012 The Go Authors. All rights reserved.
+// 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.
 
-// a package that uses unsafe on the inside but not in it's api
+// Check that we cannot import the "unsafe" package when -u is supplied.
 
-package pkg
+package a
 
-import "unsafe"
+import "unsafe" // ERROR "import package unsafe"
 
-// this should be inlinable
 func Float32bits(f float32) uint32 {
 	return *(*uint32)(unsafe.Pointer(&f))
 }