From ade1e52cc7766114f98045a918ac01234e7998c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=87=91=E8=B1=86?= <jindou@jindoudeMacBook-Air.local>
Date: Mon, 5 Oct 2026 21:49:06 +0800
Subject: [PATCH] parse_time: handle 12 AM and 12 PM correctly on the 12-hour
 clock

The period handling added a flat +12 offset whenever the input
contained pm, which breaks both 12 o'clock cases:

    >>> parse_time('12:00 PM', locale='en_US')
    ValueError: hour must be in 0..23, not 24

    >>> parse_time('12:30 AM', locale='en_US')
    datetime.time(12, 30)     # midnight parsed as half past noon

en_US's own medium time format is 'h:mm:ss a', so parsing noon in the
most common locale crashes and midnight silently lands on the wrong
side of the day. Convert the 12-hour clock properly: 12 AM is 00:00
and 12 PM is 12:00, only 1-11 AM/PM shift by twelve hours.
---
 babel/dates.py      | 14 +++++++++-----
 tests/test_dates.py |  6 ++++++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/babel/dates.py b/babel/dates.py
index 7b626aa11..c197df573 100644
--- a/babel/dates.py
+++ b/babel/dates.py
@@ -1375,14 +1375,18 @@ def parse_time(
     # TODO: support time zones
 
     # Check if the format specifies a period to be used;
-    # if it does, look for 'pm' to figure out an offset.
-    hour_offset = 0
-    if 'a' in format_str and 'pm' in string.lower():
-        hour_offset = 12
+    # if it does, convert the hour from the 12-hour clock, on which
+    # 12 AM and 12 PM are 00:00 and 12:00 respectively.
+    hour = int(numbers[indexes['H']])
+    if 'a' in format_str:
+        if 'pm' in string.lower():
+            if hour != 12:
+                hour += 12
+        elif 'am' in string.lower() and hour == 12:
+            hour = 0
 
     # Parse up to three numbers from the string.
     minute = second = 0
-    hour = int(numbers[indexes['H']]) + hour_offset
     if len(numbers) > 1:
         minute = int(numbers[indexes['M']])
         if len(numbers) > 2:
diff --git a/tests/test_dates.py b/tests/test_dates.py
index 4f8c73907..06a3126c9 100644
--- a/tests/test_dates.py
+++ b/tests/test_dates.py
@@ -492,6 +492,12 @@ def test_parse_date_custom_format():
         ('03:30 PM', time(15, 30)),
         # test hour-only parsing
         ('4 pm', time(16, 0)),
+        # test 12 o'clock am/pm conversion: noon and midnight
+        ('12:00 pm', time(12, 0)),
+        ('12:00 PM', time(12, 0)),
+        ('12:30 am', time(0, 30)),
+        ('12 AM', time(0, 0)),
+        ('12:00:15 pm', time(12, 0, 15)),
     ],
 )
 def test_parse_time(input, expected):