Correct spacing between closing delimiter and large operators (#1857)

crates/typst-library/src/math/spacing.rs

@@ -47,8 +47,9 @@ pub(super) fn spacing(
         (Binary, _) if !script(l) => resolve(MEDIUM, l),
         (_, Binary) if !script(r) => resolve(MEDIUM, r),
 
-        // Thin spacing around large operators, unless next to a delimiter.
-        (Large, Opening | Fence) | (Closing | Fence, Large) => None,
+        // Thin spacing around large operators, unless to the left of
+        // an opening delimiter. TeXBook, p170
+        (Large, Opening | Fence) => None,
         (Large, _) => resolve(THIN, l),
         (_, Large) => resolve(THIN, r),
 

tests/typ/math/spacing.typ

@@ -13,7 +13,7 @@ $sum x, sum(x)$ \
 $sum product x$ \
 $f(x), zeta(x), "frac"(x)$ \
 $a+dots.c+b$
-
+$f(x) sin(y)$
 ---
 // Test ignored vs non-ignored spaces.
 $f (x), f(x)$ \