From eb63f10d864112ac32954c49aeb7a2f960876739 Mon Sep 17 00:00:00 2001
From: Stan Ulbrych <stanulbrych@gmail.com>
Date: Mon, 14 Apr 2025 18:26:51 +0100
Subject: [PATCH 1/2] Raise a warning when passing conflicting directives

Co-authored-by: Mariatta <Mariatta@users.noreply.github.com>
---
 Doc/library/datetime.rst                                 | 9 +++++++++
 Lib/_strptime.py                                         | 7 +++++--
 .../2025-04-14-18-18-00.gh-issue-124549.hcsdgf.rst       | 2 ++
 3 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2025-04-14-18-18-00.gh-issue-124549.hcsdgf.rst

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 1ce2013f05da2e..37396f6d20cbc8 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -2765,6 +2765,15 @@ Notes:
       :exc:`DeprecationWarning`. In 3.15 or later we may change this into
       an error or change the default year to a leap year. See :gh:`70647`.
 
+(11)
+   When parsing a string using :meth:`~.datetime.strptime`, if more than one
+   directives of the same time unit were used, a SyntaxWarning is raised as
+   only the last directive gets parsed and applied to the datetime object. For
+   example, if the format string contains both ``%Y`` and ``%y``, like ``%Y%y``,
+   only the last directive on the string (``%y``) gets used on the resulting
+   datetime object.
+
+
 .. rubric:: Footnotes
 
 .. [#] If, that is, we ignore the effects of Relativity
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index aa63933a49d16d..59d3f7b3cf1b84 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -357,12 +357,15 @@ def pattern(self, format):
         day_of_month_in_format = False
         def repl(m):
             format_char = m[1]
+            nonlocal year_in_format, day_of_month_in_format
             match format_char:
                 case 'Y' | 'y' | 'G':
-                    nonlocal year_in_format
+                    if year_in_format:
+                        import warnings
+                        warnings.warn("When using conflicting directives only the last one will be used.",
+                                      SyntaxWarning, skip_file_prefixes=(os.path.dirname(__file__),))
                     year_in_format = True
                 case 'd':
-                    nonlocal day_of_month_in_format
                     day_of_month_in_format = True
             return self[format_char]
         format = re_sub(r'%([OE]?\\?.?)', repl, format)
diff --git a/Misc/NEWS.d/next/Library/2025-04-14-18-18-00.gh-issue-124549.hcsdgf.rst b/Misc/NEWS.d/next/Library/2025-04-14-18-18-00.gh-issue-124549.hcsdgf.rst
new file mode 100644
index 00000000000000..24197ab185c504
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-04-14-18-18-00.gh-issue-124549.hcsdgf.rst
@@ -0,0 +1,2 @@
+Raise a warning in :func:`datetime.datetime.strptime` and :func:`datetime.date.strptime`
+when conflicting directives are provided.

From e670d33772fa88ab7367fb7d093fcad6ff2e5054 Mon Sep 17 00:00:00 2001
From: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
Date: Mon, 19 May 2025 17:06:40 +0100
Subject: [PATCH 2/2] Reword

---
 Doc/library/datetime.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 37396f6d20cbc8..b6c6e1f69be528 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -2767,10 +2767,10 @@ Notes:
 
 (11)
    When parsing a string using :meth:`~.datetime.strptime`, if more than one
-   directives of the same time unit were used, a SyntaxWarning is raised as
+   directive of the same time unit is used, a SyntaxWarning is raised as
    only the last directive gets parsed and applied to the datetime object. For
    example, if the format string contains both ``%Y`` and ``%y``, like ``%Y%y``,
-   only the last directive on the string (``%y``) gets used on the resulting
+   only the last directive of the string (``%y``) gets used on the resulting
    datetime object.