Fix readline backspace/line-wrapping on linux

CHANGES.rst

@@ -1,5 +1,12 @@
 .. currentmodule:: click
 
+Version 8.x.x
+--------------
+
+-   Fix readline functionality on Linux platforms. Prompt text is now passed
+    directly to readline instead of being printed separately, allowing proper
+    backspace, line editing, and line wrapping behavior. :issue:`2968` :pr:`2969`
+
 Version 8.3.0
 --------------
 

src/click/termui.py

@@ -7,10 +7,12 @@
 import sys
 import typing as t
 from contextlib import AbstractContextManager
+from contextlib import redirect_stdout
 from gettext import gettext as _
 
 from ._compat import isatty
 from ._compat import strip_ansi
+from ._compat import WIN
 from .exceptions import Abort
 from .exceptions import UsageError
 from .globals import resolve_color_default
@@ -136,12 +138,21 @@ def prompt(
     def prompt_func(text: str) -> str:
         f = hidden_prompt_func if hide_input else visible_prompt_func
         try:
-            # Write the prompt separately so that we get nice
-            # coloring through colorama on Windows
-            echo(text.rstrip(" "), nl=False, err=err)
-            # Echo a space to stdout to work around an issue where
-            # readline causes backspace to clear the whole line.
-            return f(" ")
+            if WIN:
+                # Write the prompt separately so that we get nice
+                # coloring through colorama on Windows
+                echo(text.rstrip(" "), nl=False, err=err)
+                # Echo a space to stdout to work around an issue where
+                # readline causes backspace to clear the whole line.
+                return f(" ")
+            else:
+                # On non-Windows platforms, pass the full prompt to readline
+                # so it can properly handle line editing and cursor positioning
+                if err:
+                    with redirect_stdout(sys.stderr):
+                        return f(text)
+                else:
+                    return f(text)
         except (KeyboardInterrupt, EOFError):
             # getpass doesn't print a newline if the user aborts input with ^C.
             # Allegedly this behavior is inherited from getpass(3).

tests/test_utils.py

@@ -227,7 +227,8 @@ def f(_):
         click.echo("interrupted")
 
     out, err = capsys.readouterr()
-    assert out == "Password:\ninterrupted\n"
+    # On non-Windows, prompt is passed directly to getpass, not echoed separately
+    assert out == "\ninterrupted\n"
 
 
 def test_prompts_eof(runner):
@@ -484,8 +485,8 @@ def emulate_input(text):
     emulate_input("asdlkj\n")
     click.prompt("Prompt to stderr", err=True)
     out, err = capfd.readouterr()
-    assert out == " "
-    assert err == "Prompt to stderr:"
+    assert out == ""
+    assert err == "Prompt to stderr: "
 
     emulate_input("y\n")
     click.confirm("Prompt to stdin")