Bracket IPv6 hosts in the DSN shown and saved by \dsn

changelog.md

@@ -5,6 +5,7 @@ Bug Fixes
 --------
 * Read `/source` files and the `\e` editor file as UTF-8 instead of the locale encoding, so non-ASCII SQL no longer fails or is mis-decoded under non-UTF-8 locales.
 * Open the audit log and the `\T`/`\o` output files as UTF-8, so non-ASCII output no longer fails under non-UTF-8 locales.
+* Bracket IPv6 hosts in the DSN shown and saved by `\dsn`, so a saved alias for `::1` can be used to connect again.
 * Support `DELIMITER` in batch input (`mycli < file.sql`, `--batch`), so dumps with triggers or routines restore.
 * Read `--batch` files and read and write `--checkpoint` files as UTF-8, fixing `--resume` and non-ASCII batch files on Windows.
 

mycli/AUTHORS.txt

@@ -123,6 +123,7 @@ Contributors:
   * Wei-Lun Li
   * Shaurya Kesarwani
   * Alex Castillo
+  * Karim Masmoudi
   * Jay Hemnani
   * Alpenj
 

mycli/packages/special_commands/special_command_utils.py

@@ -167,6 +167,9 @@ def format_connection_dsn(
     if user_part := urlquote(user or ''):
         user_part = f'{user_part}@'
     host_part = host or 'localhost'
+    if ':' in host_part and not host_part.startswith('['):
+        # IPv6 literals must be bracketed so the port can be told apart
+        host_part = f'[{host_part}]'
     port_part = f':{port}' if port is not None else ''
     if db_part := urlquote(database or ''):
         db_part = f'/{db_part}'

mycli_test/pytests/test_special_utils.py

@@ -5,6 +5,7 @@
 import tempfile
 from types import SimpleNamespace
 from unittest.mock import MagicMock
+from urllib.parse import urlparse
 
 import pymysql
 import pytest
@@ -327,6 +328,21 @@ def test_format_connection_dsn_includes_ssh_jump() -> None:
     )
 
 
+def test_format_connection_dsn_brackets_ipv6_host() -> None:
+    dsn = format_connection_dsn(
+        user='alice',
+        host='::1',
+        port=3307,
+        database='prod',
+        socket=None,
+        character_set=None,
+    )
+    assert dsn == 'mysql://alice@[::1]:3307/prod'
+    uri = urlparse(dsn)
+    assert uri.hostname == '::1'
+    assert uri.port == 3307
+
+
 def test_format_connection_dsn_includes_encoded_kubectl_resource() -> None:
     assert (
         format_connection_dsn(