From c249cd9745ad6cb8f7cea31eae8f9c8771947ac6 Mon Sep 17 00:00:00 2001
From: Pedro Fontana <fontana.pedro93@gmail.com>
Date: Thu, 10 Aug 2023 17:22:24 -0300
Subject: [PATCH] Add SyscallError (#1357)

* Add constant string to VirtualMachineError::Hint error

* Add SycallError

* update CHANGELOG.md

* Update doc

* Fix str constant
---
 CHANGELOG.md                                         | 2 ++
 docs/hint_processor/builtin_hint_processor/README.md | 2 +-
 vm/src/vm/errors/hint_errors.rs                      | 4 +++-
 vm/src/vm/errors/vm_errors.rs                        | 4 +++-
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2b34801fd6..86d6fb4064 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 #### Upcoming Changes
 
+* Add HintError::SyscallError and VmErrors::HINT_ERROR_STR constant [#1357](https://github.com/lambdaclass/cairo-rs/pull/1357)
+
 * feat: make *arbitrary* feature also enable a `proptest::arbitrary::Arbitrary` implementation for `Felt252` [#1355](https://github.com/lambdaclass/cairo-vm/pull/1355)
 
 * fix: correctly display invalid signature error message [#1361](https://github.com/lambdaclass/cairo-vm/pull/1361)
diff --git a/docs/hint_processor/builtin_hint_processor/README.md b/docs/hint_processor/builtin_hint_processor/README.md
index bded207697..e7212da729 100644
--- a/docs/hint_processor/builtin_hint_processor/README.md
+++ b/docs/hint_processor/builtin_hint_processor/README.md
@@ -122,7 +122,7 @@ There are also some helpers that dont depend on the hint processor used that can
 You can also find plenty of example implementations in the [builtin hint processor folder](../../../src/hint_processor/builtin_hint_processor).
 
 ### Error Handling
-This API uses VirtualMachineError as error return type for hint functions, while its not possible to add error types to VirtualMachineError, you can use VirtualMachineError::CustomHint which receives a string and prints an error message with the format: "Custom Hint Error: [your message]".
+This API uses VirtualMachineError as error return type for hint functions, while its not possible to add error types to VirtualMachineError, you can use VirtualMachineError::CustomHint which receives a string and prints an error message with the format: "Hint Error: [your message]".
 For example, if we want our hint to return an error if ids.a is less than 0 we could write:
 
 ```rust
diff --git a/vm/src/vm/errors/hint_errors.rs b/vm/src/vm/errors/hint_errors.rs
index d94c7680a2..bcf8935c5d 100644
--- a/vm/src/vm/errors/hint_errors.rs
+++ b/vm/src/vm/errors/hint_errors.rs
@@ -42,7 +42,7 @@ pub enum HintError {
     UnknownIdentifierInternal,
     #[error("Wrong identifier type at address {0}")]
     WrongIdentifierTypeInternal(Box<Relocatable>),
-    #[error("Custom Hint Error: {0}")]
+    #[error("Hint Error: {0}")]
     CustomHint(Box<str>),
     #[error("Missing constant: {0}")]
     MissingConstant(Box<&'static str>),
@@ -182,6 +182,8 @@ pub enum HintError {
     InvalidValue(Box<(&'static str, Felt252, Felt252)>),
     #[error("Attempt to subtract with overflow: ids.m - 1")]
     NPairBitsTooLowM,
+    #[error("{0}")]
+    SyscallError(Box<str>),
 }
 
 #[cfg(test)]
diff --git a/vm/src/vm/errors/vm_errors.rs b/vm/src/vm/errors/vm_errors.rs
index 267c6545f6..711180d88a 100644
--- a/vm/src/vm/errors/vm_errors.rs
+++ b/vm/src/vm/errors/vm_errors.rs
@@ -17,6 +17,8 @@ use crate::{
 };
 use felt::Felt252;
 
+pub const HINT_ERROR_STR: &str = "Got an exception while executing a hint: ";
+
 #[derive(Debug, Error)]
 pub enum VirtualMachineError {
     #[error(transparent)]
@@ -111,7 +113,7 @@ pub enum VirtualMachineError {
     InvalidArgCount(Box<(usize, usize)>),
     #[error("Couldn't parse prime: {0}")]
     CouldntParsePrime(Box<str>),
-    #[error("Got an exception while executing a hint: {}", (*.0).1)]
+    #[error("{HINT_ERROR_STR}{}", (*.0).1)]
     Hint(Box<(usize, HintError)>),
     #[error("Unexpected Failure")]
     Unexpected,