code review 871042: runtime: turn run time errors checks into panics

test/recover.go

 // $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.
 
 // Test of basic recover functionality.
 
 package main
 
 import "runtime"
 
 func main() {
+        println("xxx")
         test1()
+        println("xxx")
         test1WithClosures()
+        println("xxx")
         test2()
+        println("xxx")
         test3()
+        println("xxx")
         test4()
+        println("xxx")
         test5()
+        println("xxx")
         test6()
+        println("xxx")
         test6WithClosures()
+        println("xxx")
         test7()
 }
 
 func die() {
         runtime.Breakpoint() // can't depend on panic
 }
 
 func mustRecover(x interface{}) {
         mustNotRecover() // because it's not a defer call
         v := recover()
@@ skipping 10 matching lines @@
         v = recover()
         if v != nil {
                 println("recover didn't recover")
                 die()
         }
 }
 
 func mustNotRecover() {
         v := recover()
         if v != nil {
-                println("spurious recover")
+                println("spurious recover", v)
                 die()
         }
 }
 
 func withoutRecover() {
         mustNotRecover() // because it's a sub-call
 }
 
 func test1() {
         defer mustNotRecover() // because mustRecover will squelch it
@@ skipping 174 matching lines @@
                 // this test checks that the defer func on the next line actually runs.
                 defer func() { ok = true }()
                 defer mustRecover(7)
                 panic(7)
         }()
         if !ok {
                 println("did not run ok func")
                 die()
         }
 }