From 43a6ff7f4c6b112e3360d658ef58a6aaba95ff1c Mon Sep 17 00:00:00 2001
From: 0xPlish <plish@hylo.so>
Date: Tue, 11 Mar 2025 21:47:00 -0700
Subject: [PATCH 1/2] implement TryFrom for FixValue variants, checking
 exponent before conversion

---
 Cargo.toml       |  2 +-
 flake.nix        |  1 +
 src/fix_value.rs | 24 +++++++++++++++++++-----
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index cdd5d4e..9632442 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ name = "fix"
 idl-build = ["anchor-lang/idl-build"]
 
 [dependencies]
-anchor-lang = "0.30"
+anchor-lang = "0.30.1"
 anyhow = "1.0.82"
 muldiv = "1.0.1"
 num-traits = "0.2.17"
diff --git a/flake.nix b/flake.nix
index f5bf4a0..9a3326e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -26,6 +26,7 @@
             openssl
             pkg-config
             rust-bin.stable.latest.complete  
+            rust-analyzer
           ];
         };
       };
diff --git a/src/fix_value.rs b/src/fix_value.rs
index e7969a2..05f40e3 100644
--- a/src/fix_value.rs
+++ b/src/fix_value.rs
@@ -1,6 +1,8 @@
 use crate::typenum::{Integer, U10};
 use crate::Fix;
-use anchor_lang::prelude::{borsh, AnchorDeserialize, AnchorSerialize, InitSpace};
+
+use anchor_lang::error::ErrorCode::InvalidNumericConversion;
+use anchor_lang::prelude::{borsh, AnchorDeserialize, AnchorSerialize, InitSpace, Result};
 use paste::paste;
 
 macro_rules! impl_fix_value {
@@ -33,13 +35,18 @@ macro_rules! impl_fix_value {
                 }
             }
 
-            impl<Bits, Exp> From<[<$sign FixValue $bits>]> for Fix<Bits, U10, Exp>
+            impl<Bits, Exp> TryFrom<[<$sign FixValue $bits>]> for Fix<Bits, U10, Exp>
             where
                 Bits: From<[<$sign:lower $bits>]>,
                 Exp: Integer,
             {
-              fn from(value: [<$sign FixValue $bits>]) -> Fix<Bits, U10, Exp> {
-                Fix::new(value.bits.into())
+              type Error = anchor_lang::error::Error;
+              fn try_from(value: [<$sign FixValue $bits>]) -> Result<Fix<Bits, U10, Exp>> {
+                if value.exp == Exp::to_i8() {
+                  Ok(Fix::new(value.bits.into()))
+                } else {
+                  Err(InvalidNumericConversion.into())
+                }
               }
             }
         }
@@ -71,7 +78,7 @@ mod tests {
                 fn [<roundtrip_into_ $sign:lower $bits>]() -> Result<()> {
                     let start = Kilo::new([<69 $sign:lower $bits>]);
                     let there: [<$sign FixValue $bits>] = start.into();
-                    let back: Kilo<[<$sign:lower $bits>]> = there.into();
+                    let back: Kilo<[<$sign:lower $bits>]> = there.try_into()?;
                     assert_eq!(there, [<$sign FixValue $bits>]::new(69, 3));
                     Ok(assert_eq!(start, back))
                 }
@@ -83,6 +90,13 @@ mod tests {
                     let back = AnchorDeserialize::deserialize(&mut bytes.as_slice())?;
                     Ok(assert_eq!(start, back))
                 }
+
+                #[test]
+                fn [<wrong_exp_should_fail_ $sign:lower $bits>]() -> Result<()> {
+                    let pow11 = [<$sign FixValue $bits>]::new(42, -11);
+                    let wrong = TryInto::<Kilo<[<$sign:lower $bits>]>>::try_into(pow11);
+                    Ok(assert_eq!(Err(InvalidNumericConversion.into()), wrong))
+                }
             }
         };
     }

From 7be0f9cfd9bd935e587b36995678f6c864f5e959 Mon Sep 17 00:00:00 2001
From: 0xPlish <plish@hylo.so>
Date: Wed, 12 Mar 2025 13:31:04 -0700
Subject: [PATCH 2/2] Bump package version

---
 Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 9632442..a5201d1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "hylo-fix"
-version = "0.2.0"
+version = "0.3.0"
 edition = "2021"
 description = "Fixed-point number types with Solana Anchor support"
 authors = ["0xPlish <plish@hylo.so>", "Curtis McEnroe <programble@gmail.com>"]