Add GuildMember.permissionsIn and make ChannelResolvables more lenient

src/client/ClientDataResolver.js

@@ -113,8 +113,10 @@ class ClientDataResolver {
   /**
    * Data that can be resolved to give a Channel. This can be:
    * * An instance of a Channel
+   * * An instance of a Message (the channel the message was sent in)
+   * * An instance of a Guild (the #general channel)
    * * An ID of a Channel
-   * @typedef {Channel|string} ChannelResolvable
+   * @typedef {Channel|Guild|Message|string} ChannelResolvable
    */
 
   /**
@@ -124,6 +126,8 @@ class ClientDataResolver {
    */
   resolveChannel(channel) {
     if (channel instanceof Channel) return channel;
+    if (channel instanceof Message) return channel.channel;
+    if (channel instanceof Guild) return channel.channels.get(channel.id);
     if (typeof channel === 'string') return this.client.channels.get(channel.id);
     return null;
   }

src/structures/GuildMember.js

@@ -167,6 +167,19 @@ class GuildMember {
     return new EvaluatedPermissions(this, permissions);
   }
 
+  /**
+   * Returns `guildChannel.permissionsFor(guildMember)`. Returns evaluated permissions for a member in a guild channel.
+   * @param {ChannelResolvable} guildChannel the guild channel to use as context
+   * @returns {?EvaluatedPermissions}
+   */
+  permissionsIn(guildChannel) {
+    guildChannel = this.client.resolver.resolveChannel(guildChannel);
+    if (!guildChannel) {
+      throw new Error('supply a channel resolvable that resolves to a GuildChannel!');
+    }
+    return guildChannel.permissionsFor(this);
+  }
+
   /**
    * Checks if any of the member's roles have a permission
    * @param {PermissionResolvable} permission The permission to check for