From e256d21f238f83a48a3668ec07c80b5c004cbea0 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 10 Apr 2026 11:10:48 -0700
Subject: [PATCH] CodingGuidelines: st_mtimespec vs st_mtim vs st_mtime

Most unfortunately macOS does not support st_[amc]tim for timestamps
down to nanosecond resolution as POSIX systems.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/CodingGuidelines | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index b8670751f5..db0d6800ea 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -681,6 +681,12 @@ For C programs:
          char *dogs[] = ...;
          walk_all_dogs(dogs);
 
+ - For file timestamps, do not use "st_mtim" (and other timestamp
+   members in "struct stat") unconditionally; not everybody is POSIX
+   (grep for USE_ST_TIMESPEC).  If you only need timestamp in whole
+   second resolution, "st_mtime" should work fine everywhere.
+
+
 For Perl programs:
 
  - Most of the C guidelines above apply.