Fix #16020: allow empty required custom fields

This is a port of the following 1.2.x commits:
- 890c36e
- 7ab6eb3

See related issues #12619, #11684 for details

bug_report.php

@@ -166,15 +166,13 @@
 	$t_def = custom_field_get_definition( $t_id );
 
 	# Produce an error if the field is required but wasn't posted
-	if ( !gpc_isset_custom_field( $t_id, $t_def['type'] ) &&
-		( $t_def['require_report'] ||
-			$t_def['type'] == CUSTOM_FIELD_TYPE_ENUM ||
-			$t_def['type'] == CUSTOM_FIELD_TYPE_LIST ||
-			$t_def['type'] == CUSTOM_FIELD_TYPE_MULTILIST ||
-			$t_def['type'] == CUSTOM_FIELD_TYPE_RADIO ) ) {
+	if(   !gpc_isset_custom_field( $t_id, $t_def['type'] )
+	   && $t_def['require_report']
+	) {
 		error_parameters( lang_get_defaulted( custom_field_get_field( $t_id, 'name' ) ) );
 		trigger_error( ERROR_EMPTY_FIELD, ERROR );
 	}
+
 	if ( !custom_field_validate( $t_id, gpc_get_custom_field( "custom_field_$t_id", $t_def['type'], NULL ) ) ) {
 		error_parameters( lang_get_defaulted( custom_field_get_field( $t_id, 'name' ) ) );
 		trigger_error( ERROR_CUSTOM_FIELD_INVALID_VALUE, ERROR );
@@ -206,7 +204,7 @@
 
 # Handle custom field submission
 foreach( $t_related_custom_field_ids as $t_id ) {
-	# Do not set custom field value if user has no write access.
+	# Do not set custom field value if user has no write access
 	if( !custom_field_has_write_access( $t_id, $t_bug_id ) ) {
 		continue;
 	}
@@ -278,7 +276,7 @@
 // log status and resolution changes if they differ from the default
 if ( $t_bug_data->status != config_get('bug_submit_status') )
 	history_log_event($t_bug_id, 'status', config_get('bug_submit_status') );
-	
+
 if ( $t_bug_data->resolution != config_get('default_bug_resolution') )
 	history_log_event($t_bug_id, 'resolution', config_get('default_bug_resolution') );
 

core/custom_field_api.php

@@ -1073,12 +1073,12 @@ function custom_field_validate( $p_field_id, $p_value ) {
 			$t_valid &= ( $p_value == null ) || ( ( $p_value !== false ) && ( $p_value > 0 ) );
 			break;
 		case CUSTOM_FIELD_TYPE_CHECKBOX:
+		case CUSTOM_FIELD_TYPE_MULTILIST:
 			# Checkbox fields can hold a null value (when no checkboxes are ticked)
 			if( $p_value === '' ) {
 				break;
 			}
-			# If checkbox field value is not null then we need to validate it... (note: no "break" statement here!)
-		case CUSTOM_FIELD_TYPE_MULTILIST:
+			# If checkbox field value is not null then we need to validate it
 			$t_values = explode( '|', $p_value );
 			$t_possible_values = custom_field_prepare_possible_values( $row['possible_values'] );
 			$t_possible_values = explode( '|', $t_possible_values );
@@ -1088,6 +1088,13 @@ function custom_field_validate( $p_field_id, $p_value ) {
 		case CUSTOM_FIELD_TYPE_ENUM:
 		case CUSTOM_FIELD_TYPE_LIST:
 		case CUSTOM_FIELD_TYPE_RADIO:
+			# List fields can be empty (when they are not shown on the
+			# form, or shown with no default values and never clicked)
+			if( is_blank( $p_value ) ) {
+				break;
+			}
+
+			# If list field value is not empty then we need to validate it
 			$t_possible_values = custom_field_prepare_possible_values( $row['possible_values'] );
 			$t_values_arr = explode( '|', $t_possible_values );
 			$t_valid &= in_array( $p_value, $t_values_arr );