"Unexpected selector part type NESTED_SELECTOR_APPENDER. Anything but simple selector should have been removed from tree."

[gdelhumeau]

Hello.

I am integrating Less4j into XWiki.

However, I have an exception:

com.github.sommeri.less4j.core.problems.BugHappened: Bug, please report issue: Unexpected selector part type NESTED_SELECTOR_APPENDER. Anything but simple selector should have been removed from tree. 
 Offending place: 102:1

Source code that I try to compile (the coding style is bad because it is a generated file):

//
// Flamingo main LESS file
// --------------------------------------------------

// Imports ====================================================================
@import "before-bootstrap"; // Fixes that must be included BEFORE bootstrap
@import "bootstrap/bootstrap.less"; // Bootstrap
@import "variables"; // Bootstrap variables overrided by flamingo
@import "accordion";
@import "action-menus";
@import "admin";
@import "annotations";
@import "buttons";
@import "edit";
@import "forms";
@import "general";
@import "grid";
@import "headers";
@import "layout";
@import "livetable";
@import "messages";
@import "misc";
@import "panels";
@import "type";
@import "vertical-menus";
@import "xlist";

// Velocity Content =============================================================
//
// As the main LESS file for this skin, we can use Velocity.
// ------------------------------------------------------------------------------

// Here we initialize some variables that can be used in other LESS files

        // Colors from the new flamingo theme class
                                  @text-color: #333333;
                                          @body-bg: #F5F5F5;
                                          @xwiki-page-content-bg: #FFFFFF;
                                                    @link-color: #0088CC;
                                          @brand-primary: #0088CC;
                                          @brand-success: #008000;
                                          @brand-info: #336699;
                                          @brand-warning: #D09000;
                                          @brand-danger: #CC3333;
                                                                                                                @btn-default-color: #4D5860;
                                          @btn-default-bg: #ECECEC;
                                          @btn-primary-color: #FFFFFF;
                                          @btn-primary-bg: #0088CC;
                                          @btn-success-color: #FFFFFF;
                                          @btn-success-bg: #4D9244;
                                                                                                                @navbar-default-color: #FFFFFF;
                                          @navbar-default-bg: #222222;
                                          @navbar-default-link-color: #FFFFFF;
                                          @navbar-default-link-hover-color: #FFFFFF;
                                          @navbar-default-link-hover-bg: #2A2A2A;
                                          @navbar-default-link-active-color: #FFFFFF;
                                          @navbar-default-link-active-bg: #2A2A2A;
                                                    @dropdown-bg: #FFFFFF;
                                                    @dropdown-link-color: #333333;
                                          @dropdown-link-hover-color: #333333;
                                          @dropdown-link-hover-bg: #ECECEC;
                                                                                                                          @panel-bg: #F5F5F5;
                                          @panel-default-text: #333333;
                                                    @xwiki-border-color:                  #E8E8E8;
  @xwiki-panel-header-bg:               #ECECEC;
  @xwiki-panel-header-text:             #4D5860;
  @xwiki-background-secondary-color:    #F3F3F3;
  @xwiki-page-header-bg-color:          #FFFFFF;
  @xwiki-page-header-bg-image:          '';
  @xwiki-page-header-bg-position:       'top';

@icon-font-path:                      "/xwiki/bin/webjars/resources/path?value=bootstrap/3.2.0/fonts/";

@xwiki-accordion-title-bar-background:"/xwiki/resources/icons/xwiki/accordion.png";

@xwiki-silk-icon-folder:              "/xwiki/resources/icons/silk/folder.png";
@xwiki-silk-icon-page-white-text:     "/xwiki/resources/icons/silk/page_white_text.png";
@xwiki-silk-icon-comment:             "/xwiki/resources/icons/silk/comment.png";
@xwiki-silk-icon-attachment:          "/xwiki/resources/icons/silk/attach.png";
@xwiki-silk-icon-bullet-add:          "/xwiki/resources/icons/silk/bullet_add.png";
@xwiki-silk-icon-chart-organization:  "/xwiki/resources/icons/silk/chart_organisation.png";

@xwiki-icon-parent-edit:              "/xwiki/resources/icons/xwiki/parent_edit.gif";
@xwiki-icon-edit-section:             "/xwiki/resources/icons/xwiki/edit%2Dsection.png";
@xwiki-icon-spinner:                  "/xwiki/resources/icons/xwiki/spinner.gif";

// ==============================================================================
// NOT SENT TO THE BROWSER FROM THIS POINT
// ==============================================================================
.not-sent-to-the-browser-from-this-point{
  color: red;
}
    .colortheme-pageContentBackgroundColor{
        color: @xwiki-page-content-bg;
    }
    .colortheme-borderColor{
        color: @xwiki-border-color;
    }
    .colortheme-panelHeaderBackgroundColor{
        color: @panel-default-heading-bg;
    }
    .colortheme-textColor{
        color: @text-color;
    }
    .colortheme-linkColor{
        color: @link-color;
    }
    .colortheme-titleColor{
        color: @headings-color;
    }
    .colortheme-pageBackgroundColor{
        color: @body-bg;
    }
    .colortheme-menuBackgroundColor{
        color: @navbar-default-bg;
    }
    .colortheme-menuLinkColor{
        color: @navbar-inverse-link-color;
    }
    .colortheme-menuSelectedEntryBackgroundColor{
        color: @navbar-default-link-active-bg;
    }
    .colortheme-menuSelectedEntryLinkColor{
        color: @navbar-default-link-active-color;
    }
    .colortheme-panelBackgroundColor{
        color: @panel-bg;
    }
    .colortheme-buttonPrimaryTextColor{
        color: @btn-primary-color;
    }
    .colortheme-buttonPrimaryBackgroundColor{
        color: @btn-primary-bg;
    }
    .colortheme-buttonSecondaryTextColor{
        color: @btn-default-color;
    }
    .colortheme-buttonSecondaryBackgroundColor{
        color: @btn-default-bg;
    }
    .colortheme-menuAddEntryLinkColor{
        color: @btn-success-color;
    }
    .colortheme-menuAddEntryBackgroundColor{
        color: @btn-success-bg;
    }
    .colortheme-highlightColor{
        color: @nav-link-hover-bg;
    }
    .colortheme-notificationSuccessColor{
        color: @brand-success;
    }
    .colortheme-notificationInfoColor{
        color: @brand-info;
    }
    .colortheme-notificationWarningColor{
        color: @brand-warning;
    }
    .colortheme-notificationErrorColor{
        color: @brand-danger;
    }

Thanks, Guillaume

[SomMeri]

The problem is caused by one of the imported files - if I remove imports and add missing variable everything compiles. The error does not says which one, I will add that print into BugHappened event.

Could you please put breakpoint into BugHappened and see what file is returned by offendingNode.getSourceLine()? It would help greatly if I could get line 102 of that file.

[gdelhumeau]

The file is: https://github.com/twbs/bootstrap/blob/v3.2.0/less/mixins/vendor-prefixes.less#L102

The line 102 is:

&::-moz-placeholder           { color: @color;   // Firefox

[SomMeri]

One way to reproduce the problem:

@import (reference) "less/bootstrap.less"; 
.placeholder();

Important notes:

• The .placeholder mixin must be imported for it to fail.
• Whole bootstrap must be imported for it to fail.

Following construction works correctly:

.placeholder(@color: @input-color-placeholder) {
  &::-moz-placeholder  { 
    color: @color;   
    opacity: 1; 
  } 
}
@input-color-placeholder: red;

.placeholder();

Following construction works correctly too:

@import "less/mixins/vendor-prefixes.less"; // Bootstrap
@input-color-placeholder:red;

.placeholder();

[SomMeri]

Smallest reproduce so far:

.placeholder() {
  &::-webkit-input-placeholder  { color: red; }
}
.modal-footer {
  &:extend(.clearfix all); 
}
.placeholder();

Error is reported on line 2:

Offending place: .../bootstrap-3.2.0-less/flamingo-m.less 2:1

[SomMeri]

The issue I could reproduce is now fixed, so I'm closing the issue. If the current master or the next release does not fix your problem, please re-open.

[SomMeri]

I released new version 1.8.4, your problem should be fixed there. If it is not, please re-open this issue.