From 3f67be49b4be64ef8a5ffe98d3bd0c85295948bf Mon Sep 17 00:00:00 2001
From: Thomas Boerger <thomas@webhippie.de>
Date: Tue, 4 May 2021 10:28:45 +0200
Subject: [PATCH] Respec envconfig tag within usage

---
 usage.go | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/usage.go b/usage.go
index aebadb0..8c60566 100644
--- a/usage.go
+++ b/usage.go
@@ -125,7 +125,13 @@ func Usagef(prefix string, spec interface{}, out io.Writer, format string) error
 
 	// Specify the default usage template functions
 	functions := template.FuncMap{
-		"usage_key":         func(v varInfo) string { return v.Key },
+		"usage_key": func(v varInfo) string {
+			val := v.Tags.Get("envconfig")
+			if val != "" {
+				return strings.ToUpper(val)
+			}
+			return v.Key
+		},
 		"usage_description": func(v varInfo) string { return v.Tags.Get("desc") },
 		"usage_type":        func(v varInfo) string { return toTypeDescription(v.Field.Type()) },
 		"usage_default":     func(v varInfo) string { return v.Tags.Get("default") },