From 2dab9c81d1858a48b9d6444220ead7f48acecf66 Mon Sep 17 00:00:00 2001
From: Folkert <folkert@folkertdev.nl>
Date: Fri, 23 Apr 2021 11:22:32 +0200
Subject: [PATCH] use invoke

---
 compiler/mono/src/inc_dec.rs | 12 ++++++++++--
 compiler/mono/src/ir.rs      | 16 ++++++++--------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/compiler/mono/src/inc_dec.rs b/compiler/mono/src/inc_dec.rs
index e3d7b86226..89405474a1 100644
--- a/compiler/mono/src/inc_dec.rs
+++ b/compiler/mono/src/inc_dec.rs
@@ -728,7 +728,13 @@ impl<'a> Context<'a> {
 
                 // the result of an invoke should not be touched in the fail branch
                 // but it should be present in the pass branch (otherwise it would be dead)
-                debug_assert!(case_live_vars.contains(symbol));
+                // NOTE: we cheat a bit here to allow `invoke` when generating code for `expect`
+                let is_dead = !case_live_vars.contains(symbol);
+
+                if is_dead && layout.is_refcounted() {
+                    panic!("A variable of a reference-counted layout is dead; that's a bug!");
+                }
+
                 case_live_vars.remove(symbol);
 
                 let fail = {
@@ -738,7 +744,9 @@ impl<'a> Context<'a> {
                     ctx.add_dec_for_alt(&case_live_vars, &alt_live_vars, b)
                 };
 
-                case_live_vars.insert(*symbol);
+                if !is_dead {
+                    case_live_vars.insert(*symbol);
+                }
 
                 let pass = {
                     // TODO should we use ctor info like Lean?
diff --git a/compiler/mono/src/ir.rs b/compiler/mono/src/ir.rs
index 7a945e6953..a04da8c89d 100644
--- a/compiler/mono/src/ir.rs
+++ b/compiler/mono/src/ir.rs
@@ -3260,7 +3260,7 @@ pub fn with_hole<'a>(
 
         EmptyRecord => Stmt::Let(assigned, Expr::Struct(&[]), Layout::Struct(&[]), hole),
 
-        Expect(_, rest) => todo!(),
+        Expect(_, _) => unreachable!("I think this is unreachable"),
 
         If {
             cond_var,
@@ -4307,14 +4307,14 @@ pub fn from_can<'a>(
                 call_type,
                 arguments,
             };
-            let test = Expr::Call(call);
 
-            let rest = Stmt::Let(
-                env.unique_symbol(),
-                test,
-                bool_layout,
-                env.arena.alloc(rest),
-            );
+            let rest = Stmt::Invoke {
+                symbol: env.unique_symbol(),
+                call,
+                layout: bool_layout,
+                pass: env.arena.alloc(rest),
+                fail: env.arena.alloc(Stmt::Rethrow),
+            };
 
             with_hole(
                 env,