From 2e91b90e332c473253c2ff91fd65da34eb709572 Mon Sep 17 00:00:00 2001
From: Son Ho
Date: Tue, 11 Jun 2024 14:06:23 +0200
Subject: Deactivate the use of tuple projectors in the Lean backend

---
 compiler/Config.ml              | 11 +++++++----
 compiler/SymbolicToPure.ml      |  2 +-
 tests/lean/NoNestedBorrows.lean |  6 ++++--
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/compiler/Config.ml b/compiler/Config.ml
index cb2c86ad..584635bc 100644
--- a/compiler/Config.ml
+++ b/compiler/Config.ml
@@ -362,16 +362,19 @@ let variant_concatenate_type_name = ref true
     ex.:
     {[
       // Rust
-      struct Foo(u32)
+      struct Foo(u32, u32)
 
       // OCaml
-      type Foo = (u32)
+      type Foo = u32 * u32
     ]}
  *)
 let use_tuple_structs = ref true
 
-let backend_has_tuple_projectors () =
-  match backend () with Lean -> true | Coq | FStar | HOL4 -> false
+let backend_has_tuple_projectors backend =
+  match backend with Lean -> true | Coq | FStar | HOL4 -> false
+
+(** Toggle the use of tuple projectors *)
+let use_tuple_projectors = ref false
 
 (** We we use nested projectors for tuple (like: [(0, 1).snd.fst]) or do
     we use better projector syntax? *)
diff --git a/compiler/SymbolicToPure.ml b/compiler/SymbolicToPure.ml
index 3975107a..87f1128d 100644
--- a/compiler/SymbolicToPure.ml
+++ b/compiler/SymbolicToPure.ml
@@ -2916,7 +2916,7 @@ and translate_ExpandAdt_one_branch (sv : V.symbolic_value)
            at once (`let (a, b, c) = x in`) *)
         || TypesUtils.type_decl_from_type_id_is_tuple_struct
              ctx.type_ctx.type_infos type_id
-           && not (Config.backend_has_tuple_projectors ())
+           && not !Config.use_tuple_projectors
       in
       if use_let_with_cons then
         (* Introduce a let binding which expands the ADT *)
diff --git a/tests/lean/NoNestedBorrows.lean b/tests/lean/NoNestedBorrows.lean
index 262fc79e..f0438050 100644
--- a/tests/lean/NoNestedBorrows.lean
+++ b/tests/lean/NoNestedBorrows.lean
@@ -553,12 +553,14 @@ def update_tuple (x : (U32 × U32)) : Result (U32 × U32) :=
 /- [no_nested_borrows::read_tuple_struct]:
    Source: 'tests/src/no_nested_borrows.rs', lines 490:0-490:52 -/
 def read_tuple_struct (x : Tuple U32 U32) : Result U32 :=
-  Result.ok x.#0
+  let (i, _) := x
+  Result.ok i
 
 /- [no_nested_borrows::update_tuple_struct]:
    Source: 'tests/src/no_nested_borrows.rs', lines 494:0-494:51 -/
 def update_tuple_struct (x : Tuple U32 U32) : Result (Tuple U32 U32) :=
-  Result.ok (1#u32, x.#1)
+  let (_, i) := x
+  Result.ok (1#u32, i)
 
 /- [no_nested_borrows::create_tuple_struct]:
    Source: 'tests/src/no_nested_borrows.rs', lines 498:0-498:61 -/
-- 
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