From 16858c9a276224ca632130e22f3bb7fcb2db3555 Mon Sep 17 00:00:00 2001
From: Christopher Illarionova <drydench@amazon.com>
Date: Wed, 14 Jan 2026 19:58:29 +0000
Subject: [PATCH] strtime: apply uppercase flag to compound specifiers

Fixes #486, Ref #513 for coming up with a better fix
---
 CHANGELOG.md               |  5 +++++
 src/fmt/strtime/mod.rs     | 32 ++++++++++++++++++++++++--------
 src/fmt/strtime/printer.rs | 22 ++++++++++++++++++++++
 3 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c6f9ab5..a171d386 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,11 @@ Update comparison with the `time` crate in the Jiff documentation.
 * [#502](https://github.com/BurntSushi/jiff/issues/502):
 Enable some non-default features for the Rust Playground deployment.
 
+Bug fixes:
+
+* [#486](https://github.com/BurntSushi/jiff/issues/486):
+Make `%^c` result in uppercase strings where appropriate.
+
 
 0.2.19 (2026-02-05)
 ===================
diff --git a/src/fmt/strtime/mod.rs b/src/fmt/strtime/mod.rs
index 383be5b3..d18d868d 100644
--- a/src/fmt/strtime/mod.rs
+++ b/src/fmt/strtime/mod.rs
@@ -668,11 +668,15 @@ pub trait Custom: Sized {
     fn format_datetime<W: Write>(
         &self,
         config: &Config<Self>,
-        _ext: &Extension,
+        ext: &Extension,
         tm: &BrokenDownTime,
         wtr: &mut W,
     ) -> Result<(), Error> {
-        tm.format_with_config(config, "%Y M%m %-d, %a %H:%M:%S", wtr)
+        if matches!(ext.flag, Some(Flag::Uppercase)) {
+            tm.format_with_config(config, "%Y M%m %-d, %^a %H:%M:%S", wtr)
+        } else {
+            tm.format_with_config(config, "%Y M%m %-d, %a %H:%M:%S", wtr)
+        }
     }
 
     /// Called when formatting a datetime with the `%x` flag.
@@ -708,11 +712,15 @@ pub trait Custom: Sized {
     fn format_12hour_time<W: Write>(
         &self,
         config: &Config<Self>,
-        _ext: &Extension,
+        ext: &Extension,
         tm: &BrokenDownTime,
         wtr: &mut W,
     ) -> Result<(), Error> {
-        tm.format_with_config(config, "%-I:%M:%S %p", wtr)
+        if matches!(ext.flag, Some(Flag::Uppercase)) {
+            tm.format_with_config(config, "%-I:%M:%S %^p", wtr)
+        } else {
+            tm.format_with_config(config, "%-I:%M:%S %p", wtr)
+        }
     }
 }
 
@@ -791,11 +799,15 @@ impl Custom for PosixCustom {
     fn format_datetime<W: Write>(
         &self,
         config: &Config<Self>,
-        _ext: &Extension,
+        ext: &Extension,
         tm: &BrokenDownTime,
         wtr: &mut W,
     ) -> Result<(), Error> {
-        tm.format_with_config(config, "%a %b %e %H:%M:%S %Y", wtr)
+        if matches!(ext.flag, Some(Flag::Uppercase)) {
+            tm.format_with_config(config, "%^a %^b %e %H:%M:%S %Y", wtr)
+        } else {
+            tm.format_with_config(config, "%a %b %e %H:%M:%S %Y", wtr)
+        }
     }
 
     fn format_date<W: Write>(
@@ -821,11 +833,15 @@ impl Custom for PosixCustom {
     fn format_12hour_time<W: Write>(
         &self,
         config: &Config<Self>,
-        _ext: &Extension,
+        ext: &Extension,
         tm: &BrokenDownTime,
         wtr: &mut W,
     ) -> Result<(), Error> {
-        tm.format_with_config(config, "%I:%M:%S %p", wtr)
+        if matches!(ext.flag, Some(Flag::Uppercase)) {
+            tm.format_with_config(config, "%I:%M:%S %^p", wtr)
+        } else {
+            tm.format_with_config(config, "%I:%M:%S %p", wtr)
+        }
     }
 }
 
diff --git a/src/fmt/strtime/printer.rs b/src/fmt/strtime/printer.rs
index 85817ba0..4688bc9d 100644
--- a/src/fmt/strtime/printer.rs
+++ b/src/fmt/strtime/printer.rs
@@ -1421,6 +1421,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn ok_format_compound_uppercase() {
+        let f = |fmt: &str, date: DateTime| format(fmt, date).unwrap();
+
+        insta::assert_snapshot!(
+            f("%^c", date(2024, 7, 14).at(0, 0, 0, 0)),
+            @"2024 M07 14, SUN 00:00:00",
+        );
+        insta::assert_snapshot!(
+            f("%^x", date(2024, 7, 14).at(0, 0, 0, 0)),
+            @"2024 M07 14",
+        );
+        insta::assert_snapshot!(
+            f("%^X", date(2024, 7, 14).at(8, 30, 0, 0)),
+            @"08:30:00",
+        );
+        insta::assert_snapshot!(
+            f("%^r", date(2024, 7, 14).at(8, 30, 0, 0)),
+            @"8:30:00 AM",
+        );
+    }
+
     #[test]
     fn ok_format_posix_locale() {
         let f = |fmt: &str, date: DateTime| {