Merge pull request #3616 from rtfeldman/i3614

Compile branches in the presence of degenerate patterns

crates/compiler/test_gen/src/gen_primitives.rs

@@ -3651,7 +3651,25 @@ fn shared_pattern_variable_in_when_branches() {
 }
 
 #[test]
-#[ignore = "TODO currently fails in alias analysis because `B y` does not introduce `x`"]
+#[cfg(any(feature = "gen-llvm"))]
+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]
 #[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]
 fn symbol_not_bound_in_all_patterns_runs_when_bound_pattern_reached() {
     assert_evals_to!(
@@ -3662,6 +3680,28 @@ fn symbol_not_bound_in_all_patterns_runs_when_bound_pattern_reached() {
             "#
         ),
         15u8,
-        u8
+        u8,
+        |x| x,
+        true // allow errors
+    );
+}
+
+#[test]
+#[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]
+#[should_panic(
+    expected = r#"Roc failed with message: "Hit a branch pattern that does not bind all symbols its body needs"#
+)]
+fn runtime_error_when_degenerate_pattern_reached() {
+    assert_evals_to!(
+        indoc!(
+            r#"
+            when B 15u8 is
+                A x | B y -> x + 5u8
+            "#
+        ),
+        15u8,
+        u8,
+        |x| x,
+        true // allow errors
     );
 }