From 4c4b770c27f61d10f7358c1b87df899925fcbbc6 Mon Sep 17 00:00:00 2001
From: lilydjwg <lilydjwg@gmail.com>
Date: Thu, 24 Jun 2021 11:18:35 +0800
Subject: [PATCH] docs: clarify behavior when `from_pattern` is not matched

[skip ci]
---
 docs/usage.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docs/usage.rst b/docs/usage.rst
index 001c0a7..83d2cf2 100644
--- a/docs/usage.rst
+++ b/docs/usage.rst
@@ -153,6 +153,9 @@ from_pattern, to_pattern
   Both are Python-compatible regular expressions. If ``from_pattern`` is found
   in the version string, it will be replaced with ``to_pattern``.
 
+  If ``from_pattern`` is not found, the version string remains unchanged and no
+  error is emitted.
+
 missing_ok
   Suppress warnings and errors if a version checking module finds nothing.
   Currently only ``regex`` supports it.