fix: non-convergence when an empty heading has attachments

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Bug fix: Previously, empty headings with attachments like `= <label>` or `= //` will be formatted as `=  <label>` or `=  //` (an extra space is inserted), which does not converge. Now it is fixed.
+
 ## v0.13.18 - [2025-10-11]
 
 - Bug fix: Previously, `@typstyle off` is not correctly recognized for `{table,grid}.{header,footer}`. Now it is fixed.

crates/typstyle-core/src/pretty/markup.rs

@@ -86,8 +86,12 @@ impl<'a> PrettyPrinter<'a> {
         self.convert_flow_like(ctx, heading.to_untyped(), |ctx, child, _| {
             if child.kind() == SyntaxKind::HeadingMarker {
                 FlowItem::spaced(self.arena.text(child.text().as_str()))
-            } else if let Some(markup) = child.cast() {
-                FlowItem::spaced(self.convert_markup_impl(ctx, markup, MarkupScope::InlineItem))
+            } else if let Some(markup) = child.cast::<Markup>() {
+                if !child.is_empty() {
+                    FlowItem::spaced(self.convert_markup_impl(ctx, markup, MarkupScope::InlineItem))
+                } else {
+                    FlowItem::none()
+                }
             } else {
                 FlowItem::none()
             }
@@ -132,7 +136,7 @@ impl<'a> PrettyPrinter<'a> {
                     .repeat(child.text().count_linebreaks()),
             ),
             SyntaxKind::Markup => {
-                if !seen_term || child.children().next().is_some() {
+                if !seen_term || !child.is_empty() {
                     // empty markup is ignored here
                     FlowItem::spaced(self.convert_markup_impl(
                         ctx,
@@ -165,7 +169,7 @@ impl<'a> PrettyPrinter<'a> {
                     .hardline()
                     .repeat(child.text().count_linebreaks()),
             ),
-            SyntaxKind::Markup if child.children().next().is_some() => {
+            SyntaxKind::Markup if !child.is_empty() => {
                 // empty markup is ignored here
                 FlowItem::spaced(self.convert_markup_impl(
                     ctx,

tests/fixtures/unit/markup/heading-empty.typ

@@ -0,0 +1,20 @@
+=     
+==   //   
+===    /*  */   
+= <label>
+  =  <label>
+  = /*
+ */<label>
+= /*  */ <label>
+  ==/*  */<label>
+   ==  /*
+ */  <label>
+==  a  <label>
+   ===  b//
+== c  //
+  = d /*  */  <label>
+==  /*  */ e<label>
+= f /*
+ */  <label>
+  ==  /*
+ */ g <label>

tests/fixtures/unit/markup/snap/heading-empty.typ-0.snap

@@ -0,0 +1,24 @@
+---
+source: tests/src/unit.rs
+input_file: tests/fixtures/unit/markup/heading-empty.typ
+---
+=
+==   //
+===    /*  */
+= <label>
+=  <label>
+= /*
+   */<label>
+= /*  */ <label>
+==/*  */<label>
+==  /*
+     */  <label>
+== a  <label>
+=== b//
+== c  //
+= d /*  */  <label>
+== /*  */ e<label>
+= f /*
+     */  <label>
+== /*
+    */ g <label>

tests/fixtures/unit/markup/snap/heading-empty.typ-120.snap

@@ -0,0 +1,24 @@
+---
+source: tests/src/unit.rs
+input_file: tests/fixtures/unit/markup/heading-empty.typ
+---
+=
+==   //
+===    /*  */
+= <label>
+=  <label>
+= /*
+   */<label>
+= /*  */ <label>
+==/*  */<label>
+==  /*
+     */  <label>
+== a  <label>
+=== b//
+== c  //
+= d /*  */  <label>
+== /*  */ e<label>
+= f /*
+     */  <label>
+== /*
+    */ g <label>

tests/fixtures/unit/markup/snap/heading-empty.typ-40.snap

@@ -0,0 +1,24 @@
+---
+source: tests/src/unit.rs
+input_file: tests/fixtures/unit/markup/heading-empty.typ
+---
+=
+==   //
+===    /*  */
+= <label>
+=  <label>
+= /*
+   */<label>
+= /*  */ <label>
+==/*  */<label>
+==  /*
+     */  <label>
+== a  <label>
+=== b//
+== c  //
+= d /*  */  <label>
+== /*  */ e<label>
+= f /*
+     */  <label>
+== /*
+    */ g <label>

tests/fixtures/unit/markup/snap/heading-empty.typ-80.snap

@@ -0,0 +1,24 @@
+---
+source: tests/src/unit.rs
+input_file: tests/fixtures/unit/markup/heading-empty.typ
+---
+=
+==   //
+===    /*  */
+= <label>
+=  <label>
+= /*
+   */<label>
+= /*  */ <label>
+==/*  */<label>
+==  /*
+     */  <label>
+== a  <label>
+=== b//
+== c  //
+= d /*  */  <label>
+== /*  */ e<label>
+= f /*
+     */  <label>
+== /*
+    */ g <label>