Support syntactically directly nested list, enum, and term list (#5728)

Co-authored-by: Laurenz <laurmaedje@gmail.com>

crates/typst-syntax/src/parser.rs

@@ -160,7 +160,7 @@ fn list_item(p: &mut Parser) {
     p.with_nl_mode(AtNewline::RequireColumn(p.current_column()), |p| {
         let m = p.marker();
         p.assert(SyntaxKind::ListMarker);
-        markup(p, false, false, syntax_set!(RightBracket, End));
+        markup(p, true, false, syntax_set!(RightBracket, End));
         p.wrap(m, SyntaxKind::ListItem);
     });
 }
@@ -170,7 +170,7 @@ fn enum_item(p: &mut Parser) {
     p.with_nl_mode(AtNewline::RequireColumn(p.current_column()), |p| {
         let m = p.marker();
         p.assert(SyntaxKind::EnumMarker);
-        markup(p, false, false, syntax_set!(RightBracket, End));
+        markup(p, true, false, syntax_set!(RightBracket, End));
         p.wrap(m, SyntaxKind::EnumItem);
     });
 }
@@ -184,7 +184,7 @@ fn term_item(p: &mut Parser) {
             markup(p, false, false, syntax_set!(Colon, RightBracket, End));
         });
         p.expect(SyntaxKind::Colon);
-        markup(p, false, false, syntax_set!(RightBracket, End));
+        markup(p, true, false, syntax_set!(RightBracket, End));
         p.wrap(m, SyntaxKind::TermItem);
     });
 }

tests/suite/model/enum.typ

@@ -199,3 +199,13 @@ a + 0.
 + f
 #align(right)[+ align]
 + h
+
+--- issue-5719-enum-nested ---
+// Enums can be immediately nested.
+1. A
+2. 1. B
+   2. C
++ + D
+  + E
++ = F
+  G

tests/suite/model/heading.typ

@@ -148,3 +148,7 @@ Cannot be used as @intro
 // Hint: 1-16 HTML only supports <h1> to <h6>, not <h8>
 // Hint: 1-16 you may want to restructure your document so that it doesn't contain deep headings
 ======= Level 7
+
+--- issue-5719-heading-nested ---
+// Headings may not be nested like this.
+= = A

tests/suite/model/list.typ

@@ -276,3 +276,11 @@ World
 - h
 #align(right)[- i]
 - j
+
+--- issue-5719-list-nested ---
+// Lists can be immediately nested.
+- A
+- - B
+  - C
+- = D
+  E

tests/suite/model/terms.typ

@@ -90,3 +90,9 @@ Not in list
 / h: h
 #align(right)[/ i: i]
 / j: j
+
+--- issue-5719-terms-nested ---
+// Term lists can be immediately nested.
+/ Term A: 1
+/ Term B: / Term C: 2
+          / Term D: 3