Add test when bound symbols differ in branch patterns, but no bound symbol is used

crates/compiler/test_gen/src/gen_primitives.rs

@@ -3660,6 +3660,25 @@ fn shared_pattern_variable_in_when_branches() {
     );
 }
 
+#[test]
+#[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]
+fn symbol_not_bound_in_all_patterns_runs_when_no_bound_symbol_used() {
+    assert_evals_to!(
+        indoc!(
+            r#"
+            f = \t -> when t is
+                        A x | B y -> 31u8
+
+            {a: f (A 15u8), b: f (B 15u8)}
+            "#
+        ),
+        31u8,
+        u8,
+        |x| x,
+        true // allow errors
+    );
+}
+
 #[test]
 #[ignore = "TODO currently fails in alias analysis because `B y` does not introduce `x`"]
 #[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]