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authorSon Ho2024-06-12 14:46:52 +0200
committerSon Ho2024-06-12 14:46:52 +0200
commit1018aa1af83e639a6b41b5650bf3b717e7f8de68 (patch)
treeaa14af61056233f309cdedf138604f7ac0ba443f /backends
parentf5deac2b0f42e2a87fc26da50c902729e0ed1039 (diff)
Deactivate the coercion from Nat to Scalar
Diffstat (limited to 'backends')
-rw-r--r--backends/lean/Base/Arith/Scalar.lean10
-rw-r--r--backends/lean/Base/Primitives/Scalar.lean7
2 files changed, 17 insertions, 0 deletions
diff --git a/backends/lean/Base/Arith/Scalar.lean b/backends/lean/Base/Arith/Scalar.lean
index c2e4e24e..8793713b 100644
--- a/backends/lean/Base/Arith/Scalar.lean
+++ b/backends/lean/Base/Arith/Scalar.lean
@@ -80,4 +80,14 @@ example (x : Int) (h0 : 0 ≤ x) (h1 : x ≤ U32.max) :
example (x : U32) (h0 : ¬ x = U32.ofInt 0) : 0 < x.val := by
scalar_tac
+/- See this: https://aeneas-verif.zulipchat.com/#narrow/stream/349819-general/topic/U64.20trouble/near/444049757
+
+ We solved it by removing the instance `OfNat` for `Scalar`.
+ Note however that we could also solve it with a simplification lemma.
+ However, after testing, we noticed we could only apply such a lemma with
+ the rewriting tactic (not the simplifier), probably because of the use
+ of typeclasses. -/
+example {u: U64} (h1: (u : Int) < 2): (u : Int) = 0 ∨ (u : Int) = 1 := by
+ scalar_tac
+
end Arith
diff --git a/backends/lean/Base/Primitives/Scalar.lean b/backends/lean/Base/Primitives/Scalar.lean
index 8fb067e1..157ade2c 100644
--- a/backends/lean/Base/Primitives/Scalar.lean
+++ b/backends/lean/Base/Primitives/Scalar.lean
@@ -351,10 +351,17 @@ instance [Decide (Scalar.cMin ty ≤ v ∧ v ≤ Scalar.cMax ty)] : InBounds ty
@[simp] abbrev Scalar.check_bounds (ty : ScalarTy) (x : Int) : Bool :=
(Scalar.cMin ty ≤ x || Scalar.min ty ≤ x) ∧ (x ≤ Scalar.cMax ty || x ≤ Scalar.max ty)
+/- Discussion:
+ This coercion can be slightly annoying at times, because if we write
+ something like `u = 3` (where `u` is, for instance, as `U32`), then instead of
+ coercing `u` to `Int`, Lean will lift `3` to `U32`).
+ For now we deactivate it.
+
-- TODO(raitobezarius): the inbounds constraint is a bit ugly as we can pretty trivially
-- discharge the lhs on ≥ 0.
instance {ty: ScalarTy} [InBounds ty (Int.ofNat n)]: OfNat (Scalar ty) (n: ℕ) where
ofNat := Scalar.ofInt n
+-/
theorem Scalar.check_bounds_imp_in_bounds {ty : ScalarTy} {x : Int}
(h: Scalar.check_bounds ty x) :