PanicReason rework

CHANGELOG.md

@@ -19,6 +19,11 @@ Description of the upcoming release here.
 
 ### Changed
 
+#### Breaking
+
+- [#477](https://github.com/FuelLabs/fuel-vm/pull/477): The `PanicReason::UnknownPanicReason` is `0x00`.
+    The `PanicReason` now implements `From<u8>` instead of `TryFrom<u8>` and can't return an error anymore.
+
 - [#478](https://github.com/FuelLabs/fuel-vm/pull/478): The `memcopy` method is updated
     and returns `MemoryWriteOverlap` instead of `MemoryOverflow`.
 
@@ -29,12 +34,9 @@ Description of the upcoming release here.
     leaves by setting the leaf key to the hash of an existing leaf or node. This is 
     done by removing the insertion of the leaf using the leaf key.
 
-
 - [#484](https://github.com/FuelLabs/fuel-vm/pull/484): Fixed bug with not-working `CreateMetadata`.
 
 
-- [#484](https://github.com/FuelLabs/fuel-vm/pull/484): Fixed bug with not-working `CreateMetadata`.
-
 #### Breaking
 
 - [#473](https://github.com/FuelLabs/fuel-vm/pull/473): CFS and CFSI were not validating
@@ -51,6 +53,7 @@ Description of the upcoming release here.
 
 - [#478](https://github.com/FuelLabs/fuel-vm/pull/478): The `CheckedMemRange` is replaced by the `MemoryRange`.
 
+
 ## [Version 0.33.0]
 
 The release contains a lot of breaking changes. 

fuel-asm/src/encoding_tests.rs

@@ -69,43 +69,7 @@ fn opcode() {
 fn panic_reason_description() {
     let imm24 = 0xbfffff;
 
-    let reasons = vec![
-        PanicReason::Revert,
-        PanicReason::OutOfGas,
-        PanicReason::TransactionValidity,
-        PanicReason::MemoryOverflow,
-        PanicReason::ArithmeticOverflow,
-        PanicReason::ContractNotFound,
-        PanicReason::MemoryOwnership,
-        PanicReason::NotEnoughBalance,
-        PanicReason::ExpectedInternalContext,
-        PanicReason::AssetIdNotFound,
-        PanicReason::InputNotFound,
-        PanicReason::OutputNotFound,
-        PanicReason::WitnessNotFound,
-        PanicReason::TransactionMaturity,
-        PanicReason::InvalidMetadataIdentifier,
-        PanicReason::MalformedCallStructure,
-        PanicReason::ReservedRegisterNotWritable,
-        PanicReason::ErrorFlag,
-        PanicReason::InvalidImmediateValue,
-        PanicReason::ExpectedCoinInput,
-        PanicReason::MaxMemoryAccess,
-        PanicReason::MemoryWriteOverlap,
-        PanicReason::ContractNotInInputs,
-        PanicReason::InternalBalanceOverflow,
-        PanicReason::ContractMaxSize,
-        PanicReason::ExpectedUnallocatedStack,
-        PanicReason::MaxStaticContractsReached,
-        PanicReason::TransferAmountCannotBeZero,
-        PanicReason::ExpectedOutputVariable,
-        PanicReason::ExpectedParentInternalContext,
-        PanicReason::IllegalJump,
-        PanicReason::ArithmeticError,
-        PanicReason::ContractInstructionNotAllowed,
-    ];
-
-    for r in reasons {
+    for r in PanicReason::iter() {
         let b = r as u8;
         let r_p = PanicReason::try_from(b).expect("Should get panic reason");
         let w = Word::from(r as u8);

fuel-asm/src/panic_instruction.rs

@@ -1,4 +1,3 @@
-use crate::panic_reason::InvalidPanicReason;
 use crate::{Instruction, PanicReason, RawInstruction, Word};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -39,15 +38,13 @@ impl From<PanicInstruction> for Word {
     }
 }
 
-impl TryFrom<Word> for PanicInstruction {
-    type Error = InvalidPanicReason;
-
-    fn try_from(val: Word) -> Result<Self, Self::Error> {
+impl From<Word> for PanicInstruction {
+    fn from(val: Word) -> Self {
         // Safe to cast as we've shifted the 8 MSB.
         let reason_u8 = (val >> REASON_OFFSET) as u8;
         // Cast to truncate in order to remove the `reason` bits.
         let instruction = (val >> INSTR_OFFSET) as u32;
-        let reason = PanicReason::try_from(reason_u8)?;
-        Ok(Self { reason, instruction })
+        let reason = PanicReason::from(reason_u8);
+        Self { reason, instruction }
     }
 }

fuel-asm/src/panic_reason.rs

@@ -1,12 +1,14 @@
-use core::{convert, fmt};
+use core::fmt;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, strum::EnumIter)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[repr(u8)]
 #[non_exhaustive]
 /// Panic reason representation for the interpreter.
 pub enum PanicReason {
+    /// The byte can't be mapped to any known `PanicReason`.
+    UnknownPanicReason = 0x00,
     /// Found `RVRT` instruction.
     Revert = 0x01,
     /// Execution ran out of gas.
@@ -82,8 +84,6 @@ pub enum PanicReason {
     ArithmeticError = 0x23,
     /// The contract instruction is not allowed in predicates.
     ContractInstructionNotAllowed = 0x24,
-    /// The byte can't be mapped to any known `PanicReason`.
-    UnknownPanicReason = 0x25,
 }
 
 impl fmt::Display for PanicReason {
@@ -99,28 +99,11 @@ impl std::error::Error for PanicReason {
     }
 }
 
-// TODO: Remove this - `Infallible` has nothing to do with `PanicReason`.
-impl From<convert::Infallible> for PanicReason {
-    fn from(_i: convert::Infallible) -> Self {
-        unreachable!()
-    }
-}
-
-/// Failed to parse a `u8` as a valid panic reason.
-#[derive(Debug, Eq, PartialEq)]
-pub struct InvalidPanicReason;
-
-impl TryFrom<u8> for PanicReason {
-    type Error = InvalidPanicReason;
-
+impl From<u8> for PanicReason {
     /// Converts the `u8` into a `PanicReason`.
-    fn try_from(b: u8) -> Result<Self, Self::Error> {
-        if b == 0 {
-            return Err(InvalidPanicReason);
-        }
-
+    fn from(b: u8) -> Self {
         use PanicReason::*;
-        let reason = match b {
+        match b {
             0x01 => Revert,
             0x02 => OutOfGas,
             0x03 => TransactionValidity,
@@ -158,18 +141,7 @@ impl TryFrom<u8> for PanicReason {
             0x23 => ArithmeticError,
             0x24 => ContractInstructionNotAllowed,
             _ => UnknownPanicReason,
-        };
-
-        Ok(reason)
-    }
-}
-
-#[cfg(feature = "std")]
-impl From<InvalidPanicReason> for std::io::Error {
-    fn from(_: InvalidPanicReason) -> Self {
-        use std::io;
-
-        io::Error::new(io::ErrorKind::InvalidInput, "Panic reason can't be zero")
+        }
     }
 }
 
@@ -191,20 +163,21 @@ impl From<core::array::TryFromSliceError> for PanicReason {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use strum::IntoEnumIterator;
 
     #[test]
     fn test_u8_panic_reason_round_trip() {
-        const LAST_PANIC_REASON: u8 = PanicReason::UnknownPanicReason as u8;
-        let reason = PanicReason::try_from(0);
-        assert!(reason.is_err());
+        let last_known_panic_reason: u8 = PanicReason::iter().last().unwrap() as u8 + 1;
+        let reason = PanicReason::from(0);
+        assert_eq!(reason, PanicReason::UnknownPanicReason);
 
-        for i in 1..LAST_PANIC_REASON {
+        for i in 1..last_known_panic_reason {
             let reason = PanicReason::try_from(i).unwrap();
             let i2 = reason as u8;
             assert_eq!(i, i2);
         }
-        for i in LAST_PANIC_REASON..=255 {
-            let reason = PanicReason::try_from(i).unwrap();
+        for i in last_known_panic_reason..=255 {
+            let reason = PanicReason::from(i);
             let i2 = reason as u8;
             assert_eq!(PanicReason::UnknownPanicReason as u8, i2);
         }

fuel-tx/src/receipt/receipt_std.rs

@@ -365,7 +365,7 @@ impl io::Write for Receipt {
 
                 let id = id.into();
 
-                *self = Self::panic(id, PanicInstruction::try_from(reason)?, pc, is);
+                *self = Self::panic(id, PanicInstruction::from(reason), pc, is);
             }
 
             ReceiptRepr::Revert => {