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

2 files changed, 17 insertions, 0 deletions

diff --git a/libgo/go/encoding/gob/encoder.go b/libgo/go/encoding/gob/encoder.go
index d6c8fdd..40ec81b 100644
--- a/libgo/go/encoding/gob/encoder.go
+++ b/libgo/go/encoding/gob/encoder.go
@@ -215,6 +215,9 @@ func (enc *Encoder) sendTypeId(state *encoderState, ut *userTypeInfo) {
 // guaranteeing that all necessary type information has been transmitted first.
 // Passing a nil pointer to EncodeValue will panic, as they cannot be transmitted by gob.
 func (enc *Encoder) EncodeValue(value reflect.Value) error {
+	if value.Kind() == reflect.Invalid {
+		return errors.New("gob: cannot encode nil value")
+	}
 	if value.Kind() == reflect.Ptr && value.IsNil() {
 		panic("gob: cannot encode nil pointer of type " + value.Type().String())
 	}
diff --git a/libgo/go/encoding/gob/encoder_test.go b/libgo/go/encoding/gob/encoder_test.go
index 22090a1..9256848 100644
--- a/libgo/go/encoding/gob/encoder_test.go
+++ b/libgo/go/encoding/gob/encoder_test.go
@@ -830,6 +830,20 @@ func TestPtrToMapOfMap(t *testing.T) {
 	}
 }
 
+// Test that untyped nils generate an error, not a panic.
+// See Issue 16204.
+func TestCatchInvalidNilValue(t *testing.T) {
+	encodeErr, panicErr := encodeAndRecover(nil)
+	if panicErr != nil {
+		t.Fatalf("panicErr=%v, should not panic encoding untyped nil", panicErr)
+	}
+	if encodeErr == nil {
+		t.Errorf("got err=nil, want non-nil error when encoding untyped nil value")
+	} else if !strings.Contains(encodeErr.Error(), "nil value") {
+		t.Errorf("expected 'nil value' error; got err=%v", encodeErr)
+	}
+}
+
 // A top-level nil pointer generates a panic with a helpful string-valued message.
 func TestTopLevelNilPointer(t *testing.T) {
 	var ip *int