runtime: turn divide by zero, nil dereference into panics

tested on linux/amd64, linux/386, linux/arm, darwin/amd64, darwin/386.
freebsd untested; will finish in a separate CL.

for now all the panics are errorStrings.
richer structures can be added as necessary
once the mechanism is shaked out.

R=r
CC=golang-dev
http://codereview.appspot.com/906041

1 files changed, 78 insertions, 0 deletions

diff --git a/test/recover3.go b/test/recover3.go
new file mode 100644
index 000000000..f719b0ced
--- /dev/null
+++ b/test/recover3.go
@@ -0,0 +1,78 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2010 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 main
+
+import (
+	"runtime"
+	"strings"
+	"syscall"
+)
+
+var didbug bool
+
+func bug() {
+	if didbug {
+		return
+	}
+	println("BUG")
+	didbug = true
+}
+
+func check(name string, f func(), err string) {
+	defer func() {
+		v := recover()
+		if v == nil {
+			bug()
+			println(name, "did not panic")
+			return
+		}
+		runt, ok := v.(runtime.Error)
+		if !ok {
+			bug()
+			println(name, "panicked but not with runtime.Error")
+			return
+		}
+		s := runt.String()
+		if strings.Index(s, err) < 0 {
+			bug()
+			println(name, "panicked with", s, "not", err)
+			return
+		}
+	}()
+	
+	f()
+}
+
+func main() {
+	var x int
+	var x64 int64
+	var p *[10]int
+	var q *[10000]int
+	var i int
+
+	// not catching divide by zero on the arm.  is that even possible?
+	if syscall.ARCH != "arm" {
+		check("int-div-zero", func() { println(1/x) }, "integer divide by zero")
+		check("int64-div-zero", func() { println(1/x64) }, "integer divide by zero")
+	}
+
+	check("nil-deref", func() { println(p[0]) }, "nil pointer dereference")
+	check("nil-deref-1", func() { println(p[1]) }, "nil pointer dereference")
+	check("nil-deref-big", func() { println(q[5000]) }, "nil pointer dereference")
+
+	i = 99999
+	var sl []int
+	check("array-bounds", func() { println(p[i]) }, "index out of range")
+	check("slice-bounds", func() { println(sl[i]) }, "index out of range")
+	
+	var inter interface{}
+	inter = 1
+	check("type-concrete", func() { println(inter.(string)) }, "int, not string")
+	check("type-interface", func() { println(inter.(m)) }, "missing method m")
+}
+
+type m interface{ m() }