Bail with a warning when deleting custom post types without --force

features/post.feature

@@ -8,10 +8,14 @@ Feature: Manage WordPress posts
     Then STDOUT should be a number
     And save STDOUT as {POST_ID}
 
-    When I run `wp post exists {POST_ID}`
+    When I run `wp post create --post_title='Test post' --post_type="test" --porcelain`
+    Then STDOUT should be a number
+    And save STDOUT as {CUSTOM_POST_ID}
+
+    When I run `wp post exists {CUSTOM_POST_ID}`
     Then STDOUT should be:
       """
-    Success: Post with ID {POST_ID} exists.
+      Success: Post with ID {CUSTOM_POST_ID} exists.
       """
     And the return code should be 0
 
@@ -37,6 +41,19 @@ Feature: Manage WordPress posts
       Success: Deleted post {POST_ID}.
       """
 
+    When I try `wp post delete {CUSTOM_POST_ID}`
+    Then STDERR should be:
+      """
+      Warning: Posts of type 'test' do not support being sent to trash.
+      Please use the --force flag to skip trash and delete them permanently.
+      """
+
+    When I run `wp post delete {CUSTOM_POST_ID} --force`
+    Then STDOUT should be:
+      """
+      Success: Deleted post {CUSTOM_POST_ID}.
+      """
+
     When I try the previous command again
     Then the return code should be 1
 

src/Post_Command.php

@@ -447,24 +447,39 @@ public function get( $args, $assoc_args ) {
 	 *     Success: Deleted post 1294.
 	 */
 	public function delete( $args, $assoc_args ) {
-		$defaults = array(
-			'force' => false,
-		);
+		$defaults   = [ 'force' => false ];
 		$assoc_args = array_merge( $defaults, $assoc_args );
 
-		parent::_delete( $args, $assoc_args, function ( $post_id, $assoc_args ) {
-			$status = get_post_status( $post_id );
-			$post_type = get_post_type( $post_id );
-			$r = wp_delete_post( $post_id, $assoc_args['force'] );
+		parent::_delete( $args, $assoc_args, [ $this, 'delete_callback' ] );
+	}
+
+	/**
+	 * Callback used to delete a post.
+	 *
+	 * @param $post_id
+	 * @param $assoc_args
+	 * @return array
+	 */
+	protected function delete_callback( $post_id, $assoc_args ) {
+		$status    = get_post_status( $post_id );
+		$post_type = get_post_type( $post_id );
+
+		if ( ! $assoc_args['force']
+			&& ( $post_type !== 'post' && $post_type !== 'page' ) ) {
+			return [
+				'error',
+				"Posts of type '{$post_type}' do not support being sent to trash.\n"
+				. 'Please use the --force flag to skip trash and delete them permanently.',
+			];
+		}
+
+		if ( ! wp_delete_post( $post_id, $assoc_args['force'] ) ) {
+			return [ 'error', "Failed deleting post {$post_id}." ];
+		}
 
-			if ( $r ) {
-				$action = $assoc_args['force'] || 'trash' === $status || 'revision' === $post_type ? 'Deleted' : 'Trashed';
+		$action = $assoc_args['force'] || 'trash' === $status || 'revision' === $post_type ? 'Deleted' : 'Trashed';
 
-				return array( 'success', "$action post $post_id." );
-			} else {
-				return array( 'error', "Failed deleting post $post_id." );
-			}
-		} );
+		return [ 'success', "{$action} post {$post_id}." ];
 	}
 
 	/**

src/WP_CLI/CommandWithDBObject.php

@@ -103,7 +103,7 @@ protected static function process_csv_arguments_to_arrays( $assoc_args ) {
 	 *
 	 * @param array $args Collection of one or more object ids to delete.
 	 * @param array $assoc_args Any arguments needed for the callback function.
-	 * @param string $callback Function used to delete object.
+	 * @param callable $callback Function used to delete object.
 	 */
 	protected function _delete( $args, $assoc_args, $callback ) {
 		$status = 0;