docx: normalize TOCHeading gallery content controls with trailing FieldEnd paragraph (#5952)

* docx: normalize TOCHeading gallery content controls with trailing FieldEnd paragraph

* test(docx): assert TOC entries survive round-trip in section-break TOC control test

crates/docx/src/read/toc.rs

@@ -83,13 +83,14 @@ pub(super) fn toc_control_to_toc(body: &mut Blocks) {
     }
     // An empty paragraph opening the control takes the field. It may end a section, as above
     // entries in columns (#3889).
-    if engine.get(s).and_then(|b| b.as_para()).is_some_and(|p| p.is_empty()) {
+    let empty_heading = engine.get(s).and_then(|b| b.as_para()).is_some_and(|p| p.is_empty());
+    if empty_heading {
         field_to_heading(&mut engine, s + 1);
     } else {
         toc_field_to_heading(&mut engine);
     }
     if crate::write::written_toc_span(&engine) == Some((s, last)) {
-        *body = toc;
+        *body = if empty_heading { toc } else { engine };
     }
 }
 
@@ -97,7 +98,7 @@ pub(super) fn toc_control_to_toc(body: &mut Blocks) {
 /// reproduce exactly. Other imported TOCs keep their explicit boundaries, independent of styles.
 pub(super) fn toc_field_to_heading(body: &mut Blocks) {
     for i in 1..body.len() {
-        if body[i - 1].as_para().is_some_and(|p| p.props.style.as_deref() == Some("TOCHeading")) {
+        if body.get(i - 1).and_then(|b| b.as_para()).is_some_and(|p| p.props.style.as_deref() == Some("TOCHeading")) {
             field_to_heading(body, i);
         }
     }

crates/docx/tests/it/content_controls.rs

@@ -342,3 +342,57 @@ fn toc_gallery_around_a_toc_whose_heading_is_in_a_block_control_round_trips() {
         assert!(xml.rfind("</w:sdt>").unwrap() < xml.rfind(">Chapter One<").unwrap(), "pass {pass}: {xml}");
     }
 }
+
+#[test]
+fn word_toc_gallery_with_field_end_after_entries_round_trips_without_update() {
+    let style = |s: &str, inner: &str| format!(r#"<w:p><w:pPr><w:pStyle w:val="{s}"/></w:pPr>{inner}</w:p>"#);
+    let begin = r#"<w:r><w:fldChar w:fldCharType="begin"/></w:r><w:r><w:instrText xml:space="preserve"> TOC \o "1-3" \h \z \u </w:instrText></w:r><w:r><w:fldChar w:fldCharType="separate"/></w:r>"#;
+    let content = format!(
+        "{}{}{}<w:p><w:r><w:fldChar w:fldCharType=\"end\"/></w:r></w:p>",
+        style("TOCHeading", &t("Contents")),
+        style("TOC1", &format!("{begin}{}", t("Chapter One\t1"))),
+        style("TOC2", &t("Section\t2"))
+    );
+    let pr = r#"<w:id w:val="-1234567"/><w:docPartObj><w:docPartGallery w:val="Table of Contents"/><w:docPartUnique/></w:docPartObj>"#;
+    let mut bytes = package(&format!("{}{}", sdt(pr, &content), p(&t("Chapter One"))));
+    for pass in 0..2 {
+        let d = read(&bytes).unwrap();
+        bytes = write(&d).unwrap();
+        let xml = document_xml(&bytes);
+        assert_eq!(xml.matches("<w:sdt>").count(), 1, "pass {pass}: {xml}");
+        assert!(xml.contains(r#"<w:docPartGallery w:val="Table of Contents"/>"#), "pass {pass}: {xml}");
+        assert!(xml.find("</w:sdt>").unwrap() < xml.rfind(">Chapter One<").unwrap(), "pass {pass}: {xml}");
+    }
+}
+
+#[test]
+fn range_toc_without_control_stays_unwrapped_and_section_break_toc_control_hands_over() {
+    let style = |s: &str, inner: &str| format!(r#"<w:p><w:pPr><w:pStyle w:val="{s}"/></w:pPr>{inner}</w:p>"#);
+    let begin = r#"<w:r><w:fldChar w:fldCharType="begin"/></w:r><w:r><w:instrText xml:space="preserve"> TOC \o "1-3" \h \z \u </w:instrText></w:r><w:r><w:fldChar w:fldCharType="separate"/></w:r>"#;
+    // A range TOC that was never in a content control (with FieldEnd in its own paragraph) must
+    // not gain a Table of Contents w:sdt on save.
+    let bare = format!(
+        "{}{}{}<w:p><w:r><w:fldChar w:fldCharType=\"end\"/></w:r></w:p>{}",
+        style("TOCHeading", &t("Contents")),
+        style("TOC1", &format!("{begin}{}", t("Chapter One\t1"))),
+        style("TOC2", &t("Section\t2")),
+        p(&t("Chapter One")),
+    );
+    let d_bare = read(&package(&bare)).unwrap();
+    let xml_bare = document_xml(&write(&d_bare).unwrap());
+    assert_eq!(xml_bare.matches("<w:sdt>").count(), 0, "{xml_bare}");
+
+    // #3889: a Table of Contents control opening on an empty paragraph that ends a section above
+    // the entries hands its control over on read so Update Table reuses the section-break paragraph.
+    let sect_toc = format!(
+        r#"<w:p><w:pPr><w:sectPr><w:pgSz w:w="11906" w:h="16838"/></w:sectPr></w:pPr></w:p>{}{}<w:p><w:r><w:fldChar w:fldCharType="end"/></w:r></w:p>"#,
+        style("TOC1", &format!("{begin}{}", t("Chapter One\t1"))),
+        style("TOC2", &t("Section\t2")),
+    );
+    let pr = r#"<w:id w:val="-1234567"/><w:docPartObj><w:docPartGallery w:val="Table of Contents"/><w:docPartUnique/></w:docPartObj>"#;
+    let d_sect = read(&package(&format!("{}{}", sdt(pr, &sect_toc), p(&t("Chapter One"))))).unwrap();
+    assert!(controls(&d_sect).is_empty());
+    assert!(d_sect.body[0].as_para().unwrap().section.is_some());
+    let xml_sect = document_xml(&write(&d_sect).unwrap());
+    assert!(xml_sect.contains("Chapter One") && xml_sect.contains("Section"), "{xml_sect}");
+}