hugolib: Consider summary in front matter for .Summary

Add the ability to have a `summary` page variable that overrides
the auto-generated summary.  Logic for obtaining summary becomes:

  * if summary divider is present in content, use the text above it
  * if summary variables is present in page metadata, use that
  * auto-generate summary from first _x_ words of the content

Fixes #5800

1 files changed, 9 insertions, 1 deletions

diff --git a/hugolib/page__per_output.go b/hugolib/page__per_output.go
index 05b35cc87..177e0420a 100644
--- a/hugolib/page__per_output.go
+++ b/hugolib/page__per_output.go
@@ -128,6 +128,14 @@ func newPageContentOutput(p *pageState) func(f output.Format) (*pageContentOutpu
 							cp.summary = helpers.BytesToHTML(summary)
 						}
 					}
+				} else if cp.p.m.summary != "" {
+					html := cp.p.s.ContentSpec.RenderBytes(&helpers.RenderingContext{
+						Content: []byte(cp.p.m.summary), RenderTOC: false, PageFmt: cp.p.m.markup,
+						Cfg:        p.Language(),
+						DocumentID: p.File().UniqueID(), DocumentName: p.File().Path(),
+						Config: cp.p.getRenderingConfig()})
+					html = cp.p.s.ContentSpec.TrimShortHTML(html)
+					cp.summary = helpers.BytesToHTML(html)
 				}
 			}
 
@@ -271,7 +279,7 @@ func (p *pageContentOutput) WordCount() int {
 }
 
 func (p *pageContentOutput) setAutoSummary() error {
-	if p.p.source.hasSummaryDivider {
+	if p.p.source.hasSummaryDivider || p.p.m.summary != "" {
 		return nil
 	}