libgo: update to Go 1.8 release candidate 1

    
    Compiler changes:
      * Change map assignment to use mapassign and assign value directly.
      * Change string iteration to use decoderune, faster for ASCII strings.
      * Change makeslice to take int, and use makeslice64 for larger values.
      * Add new noverflow field to hmap struct used for maps.
    
    Unresolved problems, to be fixed later:
      * Commented out test in go/types/sizes_test.go that doesn't compile.
      * Commented out reflect.TestStructOf test for padding after zero-sized field.
    
    Reviewed-on: https://go-review.googlesource.com/35231

gotools/:
	Updates for Go 1.8rc1.
	* Makefile.am (go_cmd_go_files): Add bug.go.
	(s-zdefaultcc): Write defaultPkgConfig.
	* Makefile.in: Rebuild.

From-SVN: r244456

1 files changed, 10 insertions, 1 deletions

diff --git a/libgo/go/io/multi.go b/libgo/go/io/multi.go
index 3a9d036..d784846 100644
--- a/libgo/go/io/multi.go
+++ b/libgo/go/io/multi.go
@@ -4,13 +4,19 @@
 
 package io
 
+type eofReader struct{}
+
+func (eofReader) Read([]byte) (int, error) {
+	return 0, EOF
+}
+
 type multiReader struct {
 	readers []Reader
 }
 
 func (mr *multiReader) Read(p []byte) (n int, err error) {
 	for len(mr.readers) > 0 {
-		// Optimization to flatten nested multiReaders (Issue 13558)
+		// Optimization to flatten nested multiReaders (Issue 13558).
 		if len(mr.readers) == 1 {
 			if r, ok := mr.readers[0].(*multiReader); ok {
 				mr.readers = r.readers
@@ -19,6 +25,9 @@ func (mr *multiReader) Read(p []byte) (n int, err error) {
 		}
 		n, err = mr.readers[0].Read(p)
 		if err == EOF {
+			// Use eofReader instead of nil to avoid nil panic
+			// after performing flatten (Issue 18232).
+			mr.readers[0] = eofReader{} // permit earlier GC
 			mr.readers = mr.readers[1:]
 		}
 		if n > 0 || err != EOF {