From d9db70cabdc9cb10cd5584464b8adb9a24545b92 Mon Sep 17 00:00:00 2001
From: Olivia Kinnear <51250849+superatomic@users.noreply.github.com>
Date: Sat, 29 Jul 2023 17:14:02 -0500
Subject: [PATCH] bash version support shows warning instead of error

---
 CHANGES.rst                   |  1 +
 src/click/shell_completion.py | 13 ++++++++-----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index 35a0ff428..3662e5696 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -6,6 +6,7 @@ Version 8.1.7
 Unreleased
 
 -   Fix issue with regex flags in shell completion. :issue:`2581`
+-   Bash version detection issues a warning instead of an error. :issue:`2574`
 
 
 Version 8.1.6
diff --git a/src/click/shell_completion.py b/src/click/shell_completion.py
index 9091f787e..af4a57a23 100644
--- a/src/click/shell_completion.py
+++ b/src/click/shell_completion.py
@@ -301,7 +301,8 @@ class BashComplete(ShellComplete):
     name = "bash"
     source_template = _SOURCE_BASH
 
-    def _check_version(self) -> None:
+    @staticmethod
+    def _check_version() -> None:
         import subprocess
 
         output = subprocess.run(
@@ -313,15 +314,17 @@ def _check_version(self) -> None:
             major, minor = match.groups()
 
             if major < "4" or major == "4" and minor < "4":
-                raise RuntimeError(
+                echo(
                     _(
                         "Shell completion is not supported for Bash"
                         " versions older than 4.4."
-                    )
+                    ),
+                    err=True,
                 )
         else:
-            raise RuntimeError(
-                _("Couldn't detect Bash version, shell completion is not supported.")
+            echo(
+                _("Couldn't detect Bash version, shell completion is not supported."),
+                err=True,
             )
 
     def source(self) -> str: