Formerly stdio/stdio.h.~40~

diff --git a/stdio/stdio.h b/stdio/stdio.h
index b3a8500..ca58d32 100644 (file)
--- a/stdio/stdio.h
+++ b/stdio/stdio.h
@@ -181,10 +181,12 @@ struct __stdio_file
    with `__'.  All of these may evaluate their arguments more than once.  */
 
 
-/* Nonzero if STREAM is a valid stream.  */
+/* Nonzero if STREAM is a valid stream.
+   STREAM must be a modifiable lvalue (wow, I got to use that term).
+   See stdio/glue.c for what the confusing bit is about.  */
 #define        __validfp(stream)                                                     \
   (stream != NULL && ((stream->__magic == _GLUEMAGIC &&                              \
-                      (stream = (FILE *) &((int *) stream)[1])),             \
+                      (stream = *(FILE **) ((int *) stream)[1])),            \
                      (stream->__magic == _IOMAGIC)))                         \
 
 /* Clear the error and EOF indicators of STREAM.  */