# HG changeset patch
# Parent  ccf42cdffc6d5ba3e0f11e3d84c58d413041292d
Issue #1927: Always write input() to stdout

Initial patch contributed by Michael Domingues.

diff -r ccf42cdffc6d Lib/test/test_builtin.py
--- a/Lib/test/test_builtin.py	Sat Dec 05 05:42:18 2015 +0000
+++ b/Lib/test/test_builtin.py	Tue Jan 19 02:59:34 2016 +0000
@@ -9,6 +9,7 @@
 import pickle
 import platform
 import random
+import subprocess
 import sys
 import traceback
 import types
@@ -1493,6 +1494,19 @@
     """Tests that use a pseudo terminal to guarantee stdin and stdout are
     terminals in the test environment"""
 
+    def read_master(self, fd):
+        # Beware of Linux raising EIO when the slave is closed
+        child_output = bytearray()
+        while True:
+            try:
+                chunk = os.read(fd, 3000)
+            except OSError:  # Assume EIO
+                break
+            if not chunk:
+                break
+            child_output.extend(chunk)
+        return child_output
+
     def run_child(self, child, terminal_input):
         r, w = os.pipe()  # Pipe test results from child back to parent
         try:
@@ -1530,16 +1544,7 @@
         # Check the result was got and corresponds to the user's terminal input
         if len(lines) != 2:
             # Something went wrong, try to get at stderr
-            # Beware of Linux raising EIO when the slave is closed
-            child_output = bytearray()
-            while True:
-                try:
-                    chunk = os.read(fd, 3000)
-                except OSError:  # Assume EIO
-                    break
-                if not chunk:
-                    break
-                child_output.extend(chunk)
+            child_output = self.read_master(fd)
             os.close(fd)
             child_output = child_output.decode("ascii", "ignore")
             self.fail("got %d lines in pipe but expected 2, child output was:\n%s"
@@ -1601,6 +1606,21 @@
         )
         self.assertSequenceEqual(lines, expected)
 
+    def test_prompt_stdout(self):
+        # Issue #1927: If stdin and stdout are the original terminal, the
+        # prompt should be written to stdout, not stderr
+        [master, slave] = pty.openpty()
+        with os.fdopen(master, "wb") as writer:
+            cmd = (sys.executable, "-I", "-c", "input('prompt')")
+            # Do not capture stderr
+            with subprocess.Popen(cmd, stdin=slave, stdout=slave) as proc:
+                os.close(slave)
+                writer.write(b"quux\r")
+                writer.flush()
+                output = self.read_master(master)
+        self.assertIn(b"prompt", output)
+        self.assertEqual(proc.returncode, 0)
+
 class TestSorted(unittest.TestCase):
 
     def test_basic(self):
diff -r ccf42cdffc6d Misc/ACKS
--- a/Misc/ACKS	Sat Dec 05 05:42:18 2015 +0000
+++ b/Misc/ACKS	Tue Jan 19 02:59:34 2016 +0000
@@ -18,6 +18,7 @@
 Marc Abramowitz
 Eldar Abusalimov
 Ron Adam
+Matt Adams
 Anton Afanasyev
 Ali Afshar
 Nitika Agarwal
@@ -353,6 +354,7 @@
 Josip Djolonga
 Walter Dörwald
 Jaromir Dolecek
+Michael Domingues
 Ismail Donmez
 Robert Donohue
 Marcos Donolo
diff -r ccf42cdffc6d Misc/NEWS
--- a/Misc/NEWS	Sat Dec 05 05:42:18 2015 +0000
+++ b/Misc/NEWS	Tue Jan 19 02:59:34 2016 +0000
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #1927: The interactive interpreter and the input() builtin now print
+  their prompts to stdout, rather than stderr.
+
 - Issue #25709: Fixed problem with in-place string concatenation and utf-8 cache.
 
 - Issue #5319: New Py_FinalizeEx() API allowing Python to set an exit status
diff -r ccf42cdffc6d Parser/myreadline.c
--- a/Parser/myreadline.c	Sat Dec 05 05:42:18 2015 +0000
+++ b/Parser/myreadline.c	Tue Jan 19 02:59:34 2016 +0000
@@ -115,10 +115,10 @@
     if (p == NULL)
         return NULL;
 
+    fflush(stderr);
+    if (prompt)
+        fprintf(sys_stdout, "%s", prompt);
     fflush(sys_stdout);
-    if (prompt)
-        fprintf(stderr, "%s", prompt);
-    fflush(stderr);
 
     switch (my_fgets(p, (int)n, sys_stdin)) {
     case 0: /* Normal case */
diff -r ccf42cdffc6d Parser/pgenmain.c
--- a/Parser/pgenmain.c	Sat Dec 05 05:42:18 2015 +0000
+++ b/Parser/pgenmain.c	Tue Jan 19 02:59:34 2016 +0000
@@ -146,7 +146,7 @@
     char *q;
     if (p == NULL)
         return NULL;
-    fprintf(stderr, "%s", prompt);
+    fprintf(sys_stdout, "%s", prompt);
     q = fgets(p, n, sys_stdin);
     if (q == NULL) {
         *p = '\0';
diff -r ccf42cdffc6d Parser/tokenizer.c
--- a/Parser/tokenizer.c	Sat Dec 05 05:42:18 2015 +0000
+++ b/Parser/tokenizer.c	Tue Jan 19 02:59:34 2016 +0000
@@ -932,7 +932,7 @@
             return Py_CHARMASK(*tok->cur++);
         }
         if (tok->prompt != NULL) {
-            char *newtok = PyOS_Readline(stdin, stdout, tok->prompt);
+            char *newtok = PyOS_Readline(stdin, stderr, tok->prompt);
 #ifndef PGEN
             if (newtok != NULL) {
                 char *translated = translate_newlines(newtok, 0, tok);