Merge pull request #4350 from roc-lang/i4348

Use runtime representation of values when building structural eq

crates/compiler/gen_llvm/src/llvm/compare.rs

@@ -147,6 +147,8 @@ fn build_eq<'a, 'ctx, 'env>(
     rhs_layout: &Layout<'a>,
     when_recursive: WhenRecursive<'a>,
 ) -> BasicValueEnum<'ctx> {
+    let lhs_layout = &lhs_layout.runtime_representation(env.layout_interner);
+    let rhs_layout = &rhs_layout.runtime_representation(env.layout_interner);
     if lhs_layout != rhs_layout {
         panic!(
             "Equality of different layouts; did you have a type mismatch?\n{:?} == {:?}",

crates/compiler/test_gen/src/gen_primitives.rs

@@ -4085,3 +4085,21 @@ fn pattern_match_char() {
         RocStr
     );
 }
+
+#[test]
+#[cfg(any(feature = "gen-llvm", feature = "gen-wasm"))]
+fn issue_4348() {
+    assert_evals_to!(
+        indoc!(
+            r#"
+            str = "z"
+            (\_ ->
+                when str is
+                    "z" -> "okay"
+                    _ -> "") "FAIL"
+            "#
+        ),
+        RocStr::from("okay"),
+        RocStr
+    );
+}