Fix space collapsing for explicit paragraphs (#5749)

crates/typst-realize/src/lib.rs

@@ -729,8 +729,8 @@ fn finish(s: &mut State) -> SourceResult<()> {
         }
     })?;
 
-    // In math, spaces are top-level.
+    // In paragraph and math realization, spaces are top-level.
-    if let RealizationKind::Math = s.kind {
+    if matches!(s.kind, RealizationKind::LayoutPar | RealizationKind::Math) {
         collapse_spaces(&mut s.sink, 0);
     }
 

tests/suite/model/par.typ

@@ -215,8 +215,30 @@ Welcome \ here. Does this work well?
 #set text(hyphenate: false)
 Lorem ipsum dolor #metadata(none) nonumy eirmod tempor.
 
---- par-show ---
+--- par-show-children ---
-// This is only slightly cursed.
+// Variant 1: Prevent recursion by checking the children.
+#let p = counter("p")
+#let step = p.step()
+#let nr = context p.display()
+#show par: it => {
+  if it.body.at("children", default: ()).at(0, default: none) == step {
+    return it
+  }
+  par(step + [§#nr ] + it.body)
+}
+
+= A
+
+B
+
+C #parbreak() D
+
+#block[E]
+
+#block[F #parbreak() G]
+
+--- par-show-styles ---
+// Variant 2: Prevent recursion by observing a style.
 #let revoke = metadata("revoke")
 #show par: it => {
   if bibliography.title == revoke { return it }
@@ -229,11 +251,12 @@ Lorem ipsum dolor #metadata(none) nonumy eirmod tempor.
 
 B
 
-C #parbreak() D
+C
 
-#block[E]
+--- par-explicit-trim-space ---
+A
 
-#block[F #parbreak() G]
+#par[ B ]
 
 --- issue-4278-par-trim-before-equation ---
 #set par(justify: true)