curl_easy_setopt.md: change options when no transfer runs

Underscore this. Changing them mid-transfer may cause problems.

Fixes #21604
Reported-by: Joshua Rogers
Closes #21657

diff --git a/docs/libcurl/curl_easy_setopt.md b/docs/libcurl/curl_easy_setopt.md
index 13d966f3c319a402885e09863209e65e6a78d477..aafa00f0648253e38d465311e33aa3f287e3d348 100644 (file)
--- a/docs/libcurl/curl_easy_setopt.md
+++ b/docs/libcurl/curl_easy_setopt.md
@@ -50,6 +50,9 @@ any way reset between transfers, so if you want subsequent transfers with
 different options, you must change them between the transfers. You can
 optionally reset all options back to internal default with curl_easy_reset(3).
 
+Changing options with curl_easy_setopt(3) while a transfer is still in
+progress may cause undefined and undesired behavior.
+
 The order in which the options are set does not matter.
 
 # STRINGS