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Panic error

What it does​

The panic! macro is used to stop execution when a condition is not met. This is useful for testing and prototyping, but should be avoided in production code.

Why is this bad?​

The usage of panic! is not recommended because it will stop the execution of the caller contract.

Known problems​

While this linter detects explicit calls to panic!, there are some ways to raise a panic such as unwrap() or expect().

Example​

// example code where a warning is issued
pub fn add(&mut self, value: u32)   {
   match self.value.checked_add(value) {
       Some(v) => self.value = v,
       None => panic!("Overflow error"),
   };
}

Here is an example of code that does not raise a warning:

#[derive(Debug, PartialEq, Eq, scale::Encode, scale::Decode)]
#[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
pub enum Error {
  /// An overflow was produced while adding
  OverflowError,
}

pub fn add(&mut self, value: u32) -> Result<(), Error>  {
    match self.value.checked_add(value) {
        Some(v) => self.value = v,
        None => return Err(Error::OverflowError),
    };
    Ok(())
}

Implementation​

The detector's implementation can be found at this link.