feat: Add ability to deprecate singular config values

lib/index.js

@@ -98,12 +98,16 @@ class Config {
     const types = {}
     const defaults = {}
     this.deprecated = {}
+    this.deprecatedValues = {}
     for (const [key, def] of Object.entries(definitions)) {
       defaults[key] = def.default
       types[key] = def.type
       if (def.deprecated) {
         this.deprecated[key] = def.deprecated.trim().replace(/\n +/, '\n')
       }
+      if (def.deprecatedValues) {
+        this.deprecatedValues[key] = def.deprecatedValues
+      }
     }
 
     // populated the first time we flatten the object
@@ -507,8 +511,14 @@ class Config {
 
   [_checkDeprecated] (key, where, obj, kv) {
     // XXX(npm9+) make this throw an error
-    if (this.deprecated[key]) {
-      log.warn('config', key, this.deprecated[key])
+    const value = obj[key]
+    const hasDeprecatedValues = Array.isArray(this.deprecatedValues[key])
+    const warn =
+      (hasDeprecatedValues && this.deprecatedValues[key].includes(value)) ||
+      (!hasDeprecatedValues && this.deprecated[key])
+
+    if (warn) {
+      log.warn("config", key, this.deprecated[key])
     }
   }