From 655dc32098c36a7e44f830e3f20ec780e04f57d0 Mon Sep 17 00:00:00 2001
From: Folkert <folkert@folkertdev.nl>
Date: Fri, 20 Mar 2020 22:14:38 +0100
Subject: [PATCH] support nested pattern matches on tag unions

---
 compiler/gen/src/crane/build.rs | 19 +--------
 compiler/gen/tests/test_gen.rs  | 75 ++++++++++++++++++++++++---------
 2 files changed, 58 insertions(+), 36 deletions(-)

diff --git a/compiler/gen/src/crane/build.rs b/compiler/gen/src/crane/build.rs
index 6f7dde44b4..ab17c4b4f0 100644
--- a/compiler/gen/src/crane/build.rs
+++ b/compiler/gen/src/crane/build.rs
@@ -330,7 +330,7 @@ pub fn build_expr<'a, B: Backend>(
                     let mem_flags = MemFlags::new();
                     let expr = build_expr(env, scope, module, builder, expr, procs);
 
-                    let ret_type = layout_to_type(&field_layout, cfg.pointer_type());
+                    let ret_type = type_from_layout(cfg, field_layout);
 
                     return builder
                         .ins()
@@ -426,21 +426,6 @@ pub fn build_expr<'a, B: Backend>(
     }
 }
 
-fn layout_to_type<'a>(layout: &Layout<'a>, _pointer_type: Type) -> Type {
-    use roc_mono::layout::Builtin::*;
-
-    match layout {
-        Layout::Builtin(builtin) => match builtin {
-            Int64 => cranelift::prelude::types::I64,
-            Byte => cranelift::prelude::types::I8,
-            Bool => cranelift::prelude::types::B1,
-            Float64 => cranelift::prelude::types::F64,
-            other => panic!("I don't yet know how to make a type from {:?}", other),
-        },
-        other => panic!("I don't yet know how to make a type from {:?}", other),
-    }
-}
-
 struct Branch2<'a> {
     cond: &'a Expr<'a>,
     cond_layout: &'a Layout<'a>,
@@ -570,7 +555,7 @@ fn build_switch<'a, B: Backend>(
 
             let mem_flags = MemFlags::new();
 
-            let ret_type = layout_to_type(&new_cond_layout, env.cfg.pointer_type());
+            let ret_type = type_from_layout(env.cfg, &new_cond_layout);
 
             builder
                 .ins()
diff --git a/compiler/gen/tests/test_gen.rs b/compiler/gen/tests/test_gen.rs
index 8083e12429..adae9d07fc 100644
--- a/compiler/gen/tests/test_gen.rs
+++ b/compiler/gen/tests/test_gen.rs
@@ -1438,25 +1438,62 @@ mod test_gen {
         );
     }
 
-    //    #[test]
-    //    fn when_on_just_just() {
-    //        assert_evals_to!(
-    //            indoc!(
-    //                r#"
-    //                Maybe a : [ Nothing, Just a ]
-    //
-    //                x : Maybe (Maybe a)
-    //                x = Just (Just 41)
-    //
-    //                when x is
-    //                    Just (Just v) -> v + 0x1
-    //                    _ -> 0x1
-    //                "#
-    //            ),
-    //            42,
-    //            i64
-    //        );
-    //    }
+    #[test]
+    fn nested_tag_union() {
+        assert_evals_to!(
+            indoc!(
+                r#"
+                Maybe a : [ Nothing, Just a ]
+
+                x : Maybe (Maybe a)
+                x = Just (Just 41)
+
+                5
+                "#
+            ),
+            5,
+            i64
+        );
+    }
+
+    #[test]
+    fn nested_record_load() {
+        assert_evals_to!(
+            indoc!(
+                r#"
+                Maybe a : [ Nothing, Just a ]
+
+                x = { a : { b : 0x5 } }
+
+                y = x.a
+
+                y.b
+                "#
+            ),
+            5,
+            i64
+        );
+    }
+
+    #[test]
+    fn nested_pattern_match() {
+        assert_evals_to!(
+            indoc!(
+                r#"
+                Maybe a : [ Nothing, Just a ]
+
+                x : Maybe (Maybe a)
+                x = Just (Just 41)
+
+                when x is
+                    Just (Just v) -> v + 0x1
+                    _ -> 0x1
+                "#
+            ),
+            42,
+            i64
+        );
+    }
 
     //    #[test]
     //    fn linked_list_empty() {