libgo: update to Go1.13

    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/194698

From-SVN: r275691

1 files changed, 2 insertions, 5 deletions

diff --git a/libgo/go/os/error.go b/libgo/go/os/error.go
index 0c2e6a7..0e8e2d4 100644
--- a/libgo/go/os/error.go
+++ b/libgo/go/os/error.go
@@ -22,8 +22,6 @@ var (
 	ErrExist      = errExist()      // "file already exists"
 	ErrNotExist   = errNotExist()   // "file does not exist"
 	ErrClosed     = errClosed()     // "file already closed"
-	ErrTimeout    = errTimeout()    // "deadline exceeded"
-	ErrTemporary  = errTemporary()  // "temporary error"
 	ErrNoDeadline = errNoDeadline() // "file type does not support deadline"
 )
 
@@ -32,8 +30,6 @@ func errPermission() error { return oserror.ErrPermission }
 func errExist() error      { return oserror.ErrExist }
 func errNotExist() error   { return oserror.ErrNotExist }
 func errClosed() error     { return oserror.ErrClosed }
-func errTimeout() error    { return oserror.ErrTimeout }
-func errTemporary() error  { return oserror.ErrTemporary }
 func errNoDeadline() error { return poll.ErrNoDeadline }
 
 type timeout interface {
@@ -119,7 +115,8 @@ func underlyingErrorIs(err, target error) bool {
 	if err == target {
 		return true
 	}
-	e, ok := err.(interface{ Is(error) bool })
+	// To preserve prior behavior, only examine syscall errors.
+	e, ok := err.(syscallErrorType)
 	return ok && e.Is(target)
 }