Fix shortcode directly following a shortcode delimiter

Fixes #5402

hugolib/page_test.go

@@ -1513,7 +1513,13 @@ Content.
 	b.WithContent("page-md-shortcode-same-line.md", `---
 title: "Hugo"
 ---
-This is a {{< sc >}}.<!--more-->Same line.
+This is a {{< sc >}}<!--more-->Same line.
+`)
+
+	b.WithContent("page-md-shortcode-same-line-after.md", `---
+title: "Hugo"
+---
+Summary<!--more-->{{< sc >}}
 `)
 
 	b.WithContent("page-org-shortcode.org", `#+TITLE: T1
@@ -1547,8 +1553,13 @@ CONTENT:{{ .Content }}
 	)
 
 	b.AssertFileContent("public/page-md-shortcode-same-line/index.html",
-		"SUMMARY:<p>This is a a shortcode.</p>:END",
+		"SUMMARY:<p>This is a a shortcode</p>:END",
-		"CONTENT:<p>This is a a shortcode.</p>\n\n<p>Same line.</p>\n",
+		"CONTENT:<p>This is a a shortcode</p>\n\n<p>Same line.</p>\n",
+	)
+
+	b.AssertFileContent("public/page-md-shortcode-same-line-after/index.html",
+		"SUMMARY:<p>Summary</p>:END",
+		"CONTENT:<p>Summary</p>\n\na shortcode",
 	)
 
 	b.AssertFileContent("public/page-org-shortcode/index.html",

parser/pageparser/pagelexer.go

@@ -247,6 +247,9 @@ func lexMainSection(l *pageLexer) stateFunc {
 				// This makes it a little easier to reason about later.
 				l.consumeSpace()
 				l.emit(TypeLeadSummaryDivider)
+
+				// We have already moved to the next.
+				continue
 			}
 		}
 

parser/pageparser/pageparser_intro_test.go

@@ -68,11 +68,14 @@ var frontMatterTests = []lexerTest{
 	{"Summary divider ORG", tstORG + "\nSome text.\n# more\nSome text.\n", []Item{tstFrontMatterORG, tstSomeText, nti(TypeLeadSummaryDivider, "# more\n"), nti(tText, "Some text.\n"), tstEOF}},
 	{"Summary divider", "+++\nfoo = \"bar\"\n+++\n\nSome text.\n<!--more-->\nSome text.\n", []Item{tstFrontMatterTOML, tstSomeText, tstSummaryDivider, nti(tText, "Some text.\n"), tstEOF}},
 	{"Summary divider same line", "+++\nfoo = \"bar\"\n+++\n\nSome text.<!--more-->Some text.\n", []Item{tstFrontMatterTOML, nti(tText, "\nSome text."), nti(TypeLeadSummaryDivider, "<!--more-->"), nti(tText, "Some text.\n"), tstEOF}},
+	// https://github.com/gohugoio/hugo/issues/5402
+	{"Summary and shortcode, no space", "+++\nfoo = \"bar\"\n+++\n\nSome text.\n<!--more-->{{< sc1 >}}\nSome text.\n", []Item{tstFrontMatterTOML, tstSomeText, nti(TypeLeadSummaryDivider, "<!--more-->"), tstLeftNoMD, tstSC1, tstRightNoMD, tstSomeText, tstEOF}},
 }
 
 func TestFrontMatter(t *testing.T) {
 	t.Parallel()
 	for i, test := range frontMatterTests {
+
 		items := collect([]byte(test.input), false, lexIntroSection)
 		if !equal(items, test.items) {
 			got := crLfReplacer.Replace(fmt.Sprint(items))