From b446677edaf0e74843edde6741e8962bc1b0a703 Mon Sep 17 00:00:00 2001
From: John <j@soft.fish>
Date: Tue, 9 Jul 2024 06:13:55 -0500
Subject: [PATCH] cl-interpret: Enforce wrapping behavior

---
 compiler/cl-interpret/src/builtin.rs |  4 ++--
 compiler/cl-interpret/src/lib.rs     | 18 +++++++++++-------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/compiler/cl-interpret/src/builtin.rs b/compiler/cl-interpret/src/builtin.rs
index 702dd40..114142a 100644
--- a/compiler/cl-interpret/src/builtin.rs
+++ b/compiler/cl-interpret/src/builtin.rs
@@ -1,9 +1,9 @@
 //! Implementations of built-in functions
 
 use super::{
+    convalue::ConValue,
     env::Environment,
     error::{Error, IResult},
-    convalue::ConValue,
     BuiltIn, Callable,
 };
 use cl_ast::Sym;
@@ -183,7 +183,7 @@ builtins! {
     pub fn neg(tail) -> IResult<ConValue> {
         Ok(match tail {
             ConValue::Empty => ConValue::Empty,
-            ConValue::Int(v) => ConValue::Int(-v),
+            ConValue::Int(v) => ConValue::Int(v.wrapping_neg()),
             _ => Err(Error::TypeError)?,
         })
     }
diff --git a/compiler/cl-interpret/src/lib.rs b/compiler/cl-interpret/src/lib.rs
index 2e254e4..508b188 100644
--- a/compiler/cl-interpret/src/lib.rs
+++ b/compiler/cl-interpret/src/lib.rs
@@ -207,7 +207,7 @@ pub mod convalue {
     ops! {
         Add: add = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a + b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_add(b)),
             (ConValue::String(a), ConValue::String(b)) => (a.to_string() + &b.to_string()).into(),
             _ => Err(Error::TypeError)?
             ]
@@ -231,32 +231,36 @@ pub mod convalue {
         ]
         Div: div = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a / b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.checked_div(b).unwrap_or_else(|| {
+                eprintln!("Warning: Divide by zero in {a} / {b}"); a
+            })),
             _ => Err(Error::TypeError)?
         ]
         Mul: mul = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a * b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_mul(b)),
             _ => Err(Error::TypeError)?
         ]
         Rem: rem = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a % b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.checked_rem(b).unwrap_or_else(|| {
+                eprintln!("Warning: Divide by zero in {a} % {b}"); a
+            })),
             _ => Err(Error::TypeError)?
         ]
         Shl: shl = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a << b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_shl(b as _)),
             _ => Err(Error::TypeError)?
         ]
         Shr: shr = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a >> b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_shr(b as _)),
             _ => Err(Error::TypeError)?
         ]
         Sub: sub = [
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
-            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a - b),
+            (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_sub(b)),
             _ => Err(Error::TypeError)?
         ]
     }