#16937: document that stdin is always buffered, even when -u is used. Patch by Elena Oat.

Doc/using/cmdline.rst

@@ -269,7 +269,7 @@ Miscellaneous options
 
 .. cmdoption:: -u
 
-   Force the binary layer of the stdin, stdout and stderr streams (which is
+   Force the binary layer of the stdout and stderr streams (which is
    available as their ``buffer`` attribute) to be unbuffered. The text I/O
    layer will still be line-buffered if writing to the console, or
    block-buffered if redirected to a non-interactive file.

Misc/ACKS

@@ -896,6 +896,7 @@ Tim O'Malley
 Zooko O'Whielacronx
 Aaron Oakley
 James Oakley
+Elena Oat
 Jon Oberheide
 Pascal Oberndoerfer
 Jeffrey Ollie

Misc/python.man

@@ -172,7 +172,8 @@ that it entails.  Also disable these manipulations if
 is explicitly imported later.
 .TP
 .B \-u
-Force the binary I/O layers of stdin, stdout and stderr to be unbuffered.
+Force the binary I/O layers of stdout and stderr to be unbuffered.
+stdin is always buffered.
 The text I/O layer will still be line-buffered.
 .\" Note that there is internal buffering in readlines() and
 .\" file-object iterators ("for line in sys.stdin") which is not

Modules/main.c

@@ -77,7 +77,8 @@ static char *usage_2 = "\
 -S     : don't imply 'import site' on initialization\n\
 ";
 static char *usage_3 = "\
--u     : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=x\n\
+-u     : unbuffered binary stdout and stderr, stdin always buffered;\n\
+         also PYTHONUNBUFFERED=x\n\
          see man page for details on internal buffering relating to '-u'\n\
 -v     : verbose (trace import statements); also PYTHONVERBOSE=x\n\
          can be supplied multiple times to increase verbosity\n\