rust/rhg/src/error.rs

rhg: Add a `rhg.on-unsupported` configuration key

For now the two values are:

* `abort-silent`: silently exit with code 252, the previous default behavior
* `abort`: print an error message about what feature
  is not supported, then exit with code 252. Now the default.

Differential Revision: https://phab.mercurial-scm.org/D10091

use crate::ui::utf8_to_local;
use crate::ui::UiError;
use crate::NoRepoInCwdError;
use format_bytes::format_bytes;
use hg::config::{ConfigError, ConfigParseError};
use hg::errors::HgError;
use hg::repo::RepoError;
use hg::revlog::revlog::RevlogError;
use hg::utils::files::get_bytes_from_path;
use std::convert::From;

/// The kind of command error
#[derive(Debug)]
pub enum CommandError {
    /// Exit with an error message and "standard" failure exit code.
    Abort { message: Vec<u8> },

    /// Encountered something (such as a CLI argument, repository layout, …)
    /// not supported by this version of `rhg`. Depending on configuration
    /// `rhg` may attempt to silently fall back to Python-based `hg`, which
    /// may or may not support this feature.
    UnsupportedFeature { message: Vec<u8> },
}

impl CommandError {
    pub fn abort(message: impl AsRef<str>) -> Self {
        CommandError::Abort {
            // TODO: bytes-based (instead of Unicode-based) formatting
            // of error messages to handle non-UTF-8 filenames etc:
            // https://www.mercurial-scm.org/wiki/EncodingStrategy#Mixing_output
            message: utf8_to_local(message.as_ref()).into(),
        }
    }

    pub fn unsupported(message: impl AsRef<str>) -> Self {
        CommandError::UnsupportedFeature {
            message: utf8_to_local(message.as_ref()).into(),
        }
    }
}

/// For now we don’t differenciate between invalid CLI args and valid for `hg`
/// but not supported yet by `rhg`.
impl From<clap::Error> for CommandError {
    fn from(error: clap::Error) -> Self {
        CommandError::unsupported(error.to_string())
    }
}

impl From<HgError> for CommandError {
    fn from(error: HgError) -> Self {
        match error {
            HgError::UnsupportedFeature(message) => {
                CommandError::unsupported(message)
            }
            _ => CommandError::abort(error.to_string()),
        }
    }
}

impl From<UiError> for CommandError {
    fn from(_error: UiError) -> Self {
        // If we already failed writing to stdout or stderr,
        // writing an error message to stderr about it would be likely to fail
        // too.
        CommandError::abort("")
    }
}

impl From<RepoError> for CommandError {
    fn from(error: RepoError) -> Self {
        match error {
            RepoError::NotFound { at } => CommandError::Abort {
                message: format_bytes!(
                    b"repository {} not found",
                    get_bytes_from_path(at)
                ),
            },
            RepoError::ConfigParseError(error) => error.into(),
            RepoError::Other(error) => error.into(),
        }
    }
}

impl<'a> From<&'a NoRepoInCwdError> for CommandError {
    fn from(error: &'a NoRepoInCwdError) -> Self {
        let NoRepoInCwdError { cwd } = error;
        CommandError::Abort {
            message: format_bytes!(
                b"no repository found in '{}' (.hg not found)!",
                get_bytes_from_path(cwd)
            ),
        }
    }
}

impl From<ConfigError> for CommandError {
    fn from(error: ConfigError) -> Self {
        match error {
            ConfigError::Parse(error) => error.into(),
            ConfigError::Other(error) => error.into(),
        }
    }
}

impl From<ConfigParseError> for CommandError {
    fn from(error: ConfigParseError) -> Self {
        let ConfigParseError {
            origin,
            line,
            bytes,
        } = error;
        let line_message = if let Some(line_number) = line {
            format_bytes!(b" at line {}", line_number.to_string().into_bytes())
        } else {
            Vec::new()
        };
        CommandError::Abort {
            message: format_bytes!(
                b"config parse error in {}{}: '{}'",
                origin,
                line_message,
                bytes
            ),
        }
    }
}

impl From<(RevlogError, &str)> for CommandError {
    fn from((err, rev): (RevlogError, &str)) -> CommandError {
        match err {
            RevlogError::InvalidRevision => CommandError::abort(format!(
                "invalid revision identifier {}",
                rev
            )),
            RevlogError::AmbiguousPrefix => CommandError::abort(format!(
                "ambiguous revision identifier {}",
                rev
            )),
            RevlogError::Other(error) => error.into(),
        }
    }
}