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-rw-r--r--test/fixedbugs/issue15329.go79
1 files changed, 79 insertions, 0 deletions
diff --git a/test/fixedbugs/issue15329.go b/test/fixedbugs/issue15329.go
new file mode 100644
index 0000000..30fbf13
--- /dev/null
+++ b/test/fixedbugs/issue15329.go
@@ -0,0 +1,79 @@
+// run
+
+// Copyright 2016 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.
+
+// Previously, cmd/compile would rewrite
+//
+// check(unsafe.Pointer(testMeth(1).Pointer()), unsafe.Pointer(testMeth(2).Pointer()))
+//
+// to
+//
+// var autotmp_1 uintptr = testMeth(1).Pointer()
+// var autotmp_2 uintptr = testMeth(2).Pointer()
+// check(unsafe.Pointer(autotmp_1), unsafe.Pointer(autotmp_2))
+//
+// However, that means autotmp_1 is the only reference to the int
+// variable containing the value "1", but it's not a pointer type,
+// so it was at risk of being garbage collected by the evaluation of
+// testMeth(2).Pointer(), even though package unsafe's documentation
+// says the original code was allowed.
+//
+// Now cmd/compile rewrites it to
+//
+// var autotmp_1 unsafe.Pointer = unsafe.Pointer(testMeth(1).Pointer())
+// var autotmp_2 unsafe.Pointer = unsafe.Pointer(testMeth(2).Pointer())
+// check(autotmp_1, autotmp_2)
+//
+// to ensure the pointed-to variables are visible to the GC.
+
+package main
+
+import (
+ "fmt"
+ "reflect"
+ "runtime"
+ "unsafe"
+)
+
+func main() {
+ // Test all the different ways we can invoke reflect.Value.Pointer.
+
+ // Direct method invocation.
+ check(unsafe.Pointer(testMeth(1).Pointer()), unsafe.Pointer(testMeth(2).Pointer()))
+
+ // Invocation via method expression.
+ check(unsafe.Pointer(reflect.Value.Pointer(testMeth(1))), unsafe.Pointer(reflect.Value.Pointer(testMeth(2))))
+
+ // Invocation via interface.
+ check(unsafe.Pointer(testInter(1).Pointer()), unsafe.Pointer(testInter(2).Pointer()))
+
+ // Invocation via method value.
+ check(unsafe.Pointer(testFunc(1)()), unsafe.Pointer(testFunc(2)()))
+}
+
+func check(p, q unsafe.Pointer) {
+ a, b := *(*int)(p), *(*int)(q)
+ if a != 1 || b != 2 {
+ fmt.Printf("got %v, %v; expected 1, 2\n", a, b)
+ }
+}
+
+func testMeth(x int) reflect.Value {
+ // Force GC to run.
+ runtime.GC()
+ return reflect.ValueOf(&x)
+}
+
+type Pointerer interface {
+ Pointer() uintptr
+}
+
+func testInter(x int) Pointerer {
+ return testMeth(x)
+}
+
+func testFunc(x int) func() uintptr {
+ return testMeth(x).Pointer
+}