Fix optimized linebreaks without justification (#5236)

Author: laurmaedje

crates/typst/src/layout/inline/linebreak.rs

@@ -597,7 +597,7 @@ fn raw_cost(
     let badness = if ratio < metrics.min_ratio(approx) {
         // Overfull line always has maximum cost.
         1_000_000.0
-    } else if justify || ratio < 0.0 {
+    } else if breakpoint != Breakpoint::Mandatory || justify || ratio < 0.0 {
         // If the line shall be justified or needs shrinking, it has normal
         // badness with cost 100|ratio|^3. We limit the ratio to 10 as to not
         // get to close to our maximum cost.

tests/ref/issue-5235-linebreak-optimized-without-justify.png

@@ -123,3 +123,19 @@ For info see #link("https://myhost.tld").
 // - shaping that results in multiple glyphs in the same cluster
 #set text(font: "Noto Sans Thai")
 #h(85pt) งบิก
+
+--- issue-5235-linebreak-optimized-without-justify ---
+#set page(width: 207pt, margin: 15pt)
+#set text(11pt)
+
+#set par(linebreaks: "simple")
+Some texts feature many longer
+words. Those are often exceedingly
+challenging to break in a visually
+pleasing way.
+
+#set par(linebreaks: "optimized")
+Some texts feature many longer
+words. Those are often exceedingly
+challenging to break in a visually
+pleasing way.