//! Error reporting
#![cfg_attr(not(feature = "error-context"), allow(dead_code))]
#![cfg_attr(not(feature = "error-context"), allow(unused_imports))]
#![cfg_attr(not(feature = "error-context"), allow(unused_variables))]
#![cfg_attr(not(feature = "error-context"), allow(unused_mut))]
#![cfg_attr(not(feature = "error-context"), allow(clippy::let_and_return))]
// Std
use std::{
borrow::Cow,
convert::From,
error,
fmt::{self, Debug, Display, Formatter},
io,
result::Result as StdResult,
};
// Internal
use crate::builder::StyledStr;
use crate::builder::Styles;
use crate::output::fmt::Colorizer;
use crate::output::fmt::Stream;
use crate::parser::features::suggestions;
use crate::util::FlatMap;
use crate::util::{color::ColorChoice, SUCCESS_CODE, USAGE_CODE};
use crate::Command;
#[cfg(feature = "error-context")]
mod context;
mod format;
mod kind;
pub use format::ErrorFormatter;
pub use format::KindFormatter;
pub use kind::ErrorKind;
#[cfg(feature = "error-context")]
pub use context::ContextKind;
#[cfg(feature = "error-context")]
pub use context::ContextValue;
#[cfg(feature = "error-context")]
pub use format::RichFormatter;
#[cfg(not(feature = "error-context"))]
pub use KindFormatter as DefaultFormatter;
#[cfg(feature = "error-context")]
pub use RichFormatter as DefaultFormatter;
/// Short hand for [`Result`] type
///
/// [`Result`]: std::result::Result
pub type Result<T, E = Error> = StdResult<T, E>;
/// Command Line Argument Parser Error
///
/// See [`Command::error`] to create an error.
///
/// [`Command::error`]: crate::Command::error
pub struct Error<F: ErrorFormatter = DefaultFormatter> {
inner: Box<ErrorInner>,
phantom: std::marker::PhantomData<F>,
}
#[derive(Debug)]
struct ErrorInner {
kind: ErrorKind,
#[cfg(feature = "error-context")]
context: FlatMap<ContextKind, ContextValue>,
message: Option<Message>,
source: Option<Box<dyn error::Error + Send + Sync>>,
help_flag: Option<Cow<'static, str>>,
styles: Styles,
color_when: ColorChoice,
color_help_when: ColorChoice,
backtrace: Option<Backtrace>,
}
impl<F: ErrorFormatter> Error<F> {
/// Create an unformatted error
///
/// This is for you need to pass the error up to
/// a place that has access to the `Command` at which point you can call [`Error::format`].
///
/// Prefer [`Command::error`] for generating errors.
///
/// [`Command::error`]: crate::Command::error
pub fn raw(kind: ErrorKind, message: impl Display) -> Self {
Self::new(kind).set_message(message.to_string())
}
/// Format the existing message with the Command's context
#[must_use]
pub fn format(mut self, cmd: &mut Command) -> Self {
cmd._build_self(false);
let usage = cmd.render_usage_();
if let Some(message) = self.inner.message.as_mut() {
message.format(cmd, usage);
}
self.with_cmd(cmd)
}
/// Create an error with a pre-defined message
///
/// See also
/// - [`Error::insert`]
/// - [`Error::with_cmd`]
///
/// # Example
///
/// ```rust
/// # #[cfg(feature = "error-context")] {
/// # use clap_builder as clap;
/// # use clap::error::ErrorKind;
/// # use clap::error::ContextKind;
/// # use clap::error::ContextValue;
///
/// let cmd = clap::Command::new("prog");
///
/// let mut err = clap::Error::new(ErrorKind::ValueValidation)
/// .with_cmd(&cmd);
/// err.insert(ContextKind::InvalidArg, ContextValue::String("--foo".to_owned()));
/// err.insert(ContextKind::InvalidValue, ContextValue::String("bar".to_owned()));
///
/// err.print();
/// # }
/// ```
pub fn new(kind: ErrorKind) -> Self {
Self {
inner: Box::new(ErrorInner {
kind,
#[cfg(feature = "error-context")]
context: FlatMap::new(),
message: None,
source: None,
help_flag: None,
styles: Styles::plain(),
color_when: ColorChoice::Never,
color_help_when: ColorChoice::Never,
backtrace: Backtrace::new(),
}),
phantom: Default::default(),
}
}
/// Apply [`Command`]'s formatting to the error
///
/// Generally, this is used with [`Error::new`]
pub fn with_cmd(self, cmd: &Command) -> Self {
self.set_styles(cmd.get_styles().clone())
.set_color(cmd.get_color())
.set_colored_help(cmd.color_help())
.set_help_flag(format::get_help_flag(cmd))
}
/// Apply an alternative formatter to the error
///
/// # Example
///
/// ```rust
/// # use clap_builder as clap;
/// # use clap::Command;
/// # use clap::Arg;
/// # use clap::error::KindFormatter;
/// let cmd = Command::new("foo")
/// .arg(Arg::new("input").required(true));
/// let matches = cmd
/// .try_get_matches_from(["foo", "input.txt"])
/// .map_err(|e| e.apply::<KindFormatter>())
/// .unwrap_or_else(|e| e.exit());
/// ```
pub fn apply<EF: ErrorFormatter>(self) -> Error<EF> {
Error {
inner: self.inner,
phantom: Default::default(),
}
}
/// Type of error for programmatic processing
pub fn kind(&self) -> ErrorKind {
self.inner.kind
}
/// Additional information to further qualify the error
#[cfg(feature = "error-context")]
pub fn context(&self) -> impl Iterator<Item = (ContextKind, &ContextValue)> {
self.inner.context.iter().map(|(k, v)| (*k, v))
}
/// Lookup a piece of context
#[inline(never)]
#[cfg(feature = "error-context")]
pub fn get(&self, kind: ContextKind) -> Option<&ContextValue> {
self.inner.context.get(&kind)
}
/// Insert a piece of context
#[inline(never)]
#[cfg(feature = "error-context")]
pub fn insert(&mut self, kind: ContextKind, value: ContextValue) -> Option<ContextValue> {
self.inner.context.insert(kind, value)
}
/// Should the message be written to `stdout` or not?
#[inline]
pub fn use_stderr(&self) -> bool {
self.stream() == Stream::Stderr
}
pub(crate) fn stream(&self) -> Stream {
match self.kind() {
ErrorKind::DisplayHelp | ErrorKind::DisplayVersion => Stream::Stdout,
_ => Stream::Stderr,
}
}
/// Returns the exit code that `.exit` will exit the process with.
///
/// When the error's kind would print to `stderr` this returns `2`,
/// else it returns `0`.
pub fn exit_code(&self) -> i32 {
if self.use_stderr() {
USAGE_CODE
} else {
SUCCESS_CODE
}
}
/// Prints the error and exits.
///
/// Depending on the error kind, this either prints to `stderr` and exits with a status of `2`
/// or prints to `stdout` and exits with a status of `0`.
pub fn exit(&self) -> ! {
// Swallow broken pipe errors
let _ = self.print();
std::process::exit(self.exit_code());
}
/// Prints formatted and colored error to `stdout` or `stderr` according to its error kind
///
/// # Example
/// ```no_run
/// # use clap_builder as clap;
/// use clap::Command;
///
/// match Command::new("Command").try_get_matches() {
/// Ok(matches) => {
/// // do_something
/// },
/// Err(err) => {
/// err.print().expect("Error writing Error");
/// // do_something
/// },
/// };
/// ```
pub fn print(&self) -> io::Result<()> {
let style = self.formatted();
let color_when = if matches!(
self.kind(),
ErrorKind::DisplayHelp | ErrorKind::DisplayHelpOnMissingArgumentOrSubcommand,
) {
self.inner.color_help_when
} else {
self.inner.color_when
};
let c = Colorizer::new(self.stream(), color_when).with_content(style.into_owned());
c.print()
}
/// Render the error message to a [`StyledStr`].
///
/// # Example
/// ```no_run
/// # use clap_builder as clap;
/// use clap::Command;
///
/// match Command::new("Command").try_get_matches() {
/// Ok(matches) => {
/// // do_something
/// },
/// Err(err) => {
/// let err = err.render();
/// println!("{err}");
/// // do_something
/// },
/// };
/// ```
pub fn render(&self) -> StyledStr {
self.formatted().into_owned()
}
#[inline(never)]
fn for_app(kind: ErrorKind, cmd: &Command, styled: StyledStr) -> Self {
Self::new(kind).set_message(styled).with_cmd(cmd)
}
pub(crate) fn set_message(mut self, message: impl Into<Message>) -> Self {
self.inner.message = Some(message.into());
self
}
pub(crate) fn set_source(mut self, source: Box<dyn error::Error + Send + Sync>) -> Self {
self.inner.source = Some(source);
self
}
pub(crate) fn set_styles(mut self, styles: Styles) -> Self {
self.inner.styles = styles;
self
}
pub(crate) fn set_color(mut self, color_when: ColorChoice) -> Self {
self.inner.color_when = color_when;
self
}
pub(crate) fn set_colored_help(mut self, color_help_when: ColorChoice) -> Self {
self.inner.color_help_when = color_help_when;
self
}
pub(crate) fn set_help_flag(mut self, help_flag: Option<Cow<'static, str>>) -> Self {
self.inner.help_flag = help_flag;
self
}
/// Does not verify if `ContextKind` is already present
#[inline(never)]
#[cfg(feature = "error-context")]
pub(crate) fn insert_context_unchecked(
mut self,
kind: ContextKind,
value: ContextValue,
) -> Self {
self.inner.context.insert_unchecked(kind, value);
self
}
/// Does not verify if `ContextKind` is already present
#[inline(never)]
#[cfg(feature = "error-context")]
pub(crate) fn extend_context_unchecked<const N: usize>(
mut self,
context: [(ContextKind, ContextValue); N],
) -> Self {
self.inner.context.extend_unchecked(context);
self
}
pub(crate) fn display_help(cmd: &Command, styled: StyledStr) -> Self {
Self::for_app(ErrorKind::DisplayHelp, cmd, styled)
}
pub(crate) fn display_help_error(cmd: &Command, styled: StyledStr) -> Self {
Self::for_app(
ErrorKind::DisplayHelpOnMissingArgumentOrSubcommand,
cmd,
styled,
)
}
pub(crate) fn display_version(cmd: &Command, styled: StyledStr) -> Self {
Self::for_app(ErrorKind::DisplayVersion, cmd, styled)
}
pub(crate) fn argument_conflict(
cmd: &Command,
arg: String,
mut others: Vec<String>,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::ArgumentConflict).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
let others = match others.len() {
0 => ContextValue::None,
1 => ContextValue::String(others.pop().unwrap()),
_ => ContextValue::Strings(others),
};
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(ContextKind::PriorArg, others),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn subcommand_conflict(
cmd: &Command,
sub: String,
mut others: Vec<String>,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::ArgumentConflict).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
let others = match others.len() {
0 => ContextValue::None,
1 => ContextValue::String(others.pop().unwrap()),
_ => ContextValue::Strings(others),
};
err = err.extend_context_unchecked([
(ContextKind::InvalidSubcommand, ContextValue::String(sub)),
(ContextKind::PriorArg, others),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn empty_value(cmd: &Command, good_vals: &[String], arg: String) -> Self {
Self::invalid_value(cmd, "".to_owned(), good_vals, arg)
}
pub(crate) fn no_equals(cmd: &Command, arg: String, usage: Option<StyledStr>) -> Self {
let mut err = Self::new(ErrorKind::NoEquals).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err
.extend_context_unchecked([(ContextKind::InvalidArg, ContextValue::String(arg))]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn invalid_value(
cmd: &Command,
bad_val: String,
good_vals: &[String],
arg: String,
) -> Self {
let suggestion = suggestions::did_you_mean(&bad_val, good_vals.iter()).pop();
let mut err = Self::new(ErrorKind::InvalidValue).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(ContextKind::InvalidValue, ContextValue::String(bad_val)),
(
ContextKind::ValidValue,
ContextValue::Strings(good_vals.iter().map(|s| (*s).clone()).collect()),
),
]);
if let Some(suggestion) = suggestion {
err = err.insert_context_unchecked(
ContextKind::SuggestedValue,
ContextValue::String(suggestion),
);
}
}
err
}
pub(crate) fn invalid_subcommand(
cmd: &Command,
subcmd: String,
did_you_mean: Vec<String>,
name: String,
suggested_trailing_arg: bool,
usage: Option<StyledStr>,
) -> Self {
use std::fmt::Write as _;
let styles = cmd.get_styles();
let invalid = &styles.get_invalid();
let valid = &styles.get_valid();
let mut err = Self::new(ErrorKind::InvalidSubcommand).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
let mut suggestions = vec![];
if suggested_trailing_arg {
let mut styled_suggestion = StyledStr::new();
let _ = write!(
styled_suggestion,
"to pass '{}{subcmd}{}' as a value, use '{}{name} -- {subcmd}{}'",
invalid.render(),
invalid.render_reset(),
valid.render(),
valid.render_reset()
);
suggestions.push(styled_suggestion);
}
err = err.extend_context_unchecked([
(ContextKind::InvalidSubcommand, ContextValue::String(subcmd)),
(
ContextKind::SuggestedSubcommand,
ContextValue::Strings(did_you_mean),
),
(
ContextKind::Suggested,
ContextValue::StyledStrs(suggestions),
),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn unrecognized_subcommand(
cmd: &Command,
subcmd: String,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::InvalidSubcommand).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([(
ContextKind::InvalidSubcommand,
ContextValue::String(subcmd),
)]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn missing_required_argument(
cmd: &Command,
required: Vec<String>,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::MissingRequiredArgument).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([(
ContextKind::InvalidArg,
ContextValue::Strings(required),
)]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn missing_subcommand(
cmd: &Command,
parent: String,
available: Vec<String>,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::MissingSubcommand).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([
(ContextKind::InvalidSubcommand, ContextValue::String(parent)),
(
ContextKind::ValidSubcommand,
ContextValue::Strings(available),
),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn invalid_utf8(cmd: &Command, usage: Option<StyledStr>) -> Self {
let mut err = Self::new(ErrorKind::InvalidUtf8).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn too_many_values(
cmd: &Command,
val: String,
arg: String,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::TooManyValues).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(ContextKind::InvalidValue, ContextValue::String(val)),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn too_few_values(
cmd: &Command,
arg: String,
min_vals: usize,
curr_vals: usize,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::TooFewValues).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(
ContextKind::MinValues,
ContextValue::Number(min_vals as isize),
),
(
ContextKind::ActualNumValues,
ContextValue::Number(curr_vals as isize),
),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn value_validation(
arg: String,
val: String,
err: Box<dyn error::Error + Send + Sync>,
) -> Self {
let mut err = Self::new(ErrorKind::ValueValidation).set_source(err);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(ContextKind::InvalidValue, ContextValue::String(val)),
]);
}
err
}
pub(crate) fn wrong_number_of_values(
cmd: &Command,
arg: String,
num_vals: usize,
curr_vals: usize,
usage: Option<StyledStr>,
) -> Self {
let mut err = Self::new(ErrorKind::WrongNumberOfValues).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(
ContextKind::ExpectedNumValues,
ContextValue::Number(num_vals as isize),
),
(
ContextKind::ActualNumValues,
ContextValue::Number(curr_vals as isize),
),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
pub(crate) fn unknown_argument(
cmd: &Command,
arg: String,
did_you_mean: Option<(String, Option<String>)>,
suggested_trailing_arg: bool,
usage: Option<StyledStr>,
) -> Self {
use std::fmt::Write as _;
let styles = cmd.get_styles();
let invalid = &styles.get_invalid();
let valid = &styles.get_valid();
let mut err = Self::new(ErrorKind::UnknownArgument).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
let mut suggestions = vec![];
if suggested_trailing_arg {
let mut styled_suggestion = StyledStr::new();
let _ = write!(
styled_suggestion,
"to pass '{}{arg}{}' as a value, use '{}-- {arg}{}'",
invalid.render(),
invalid.render_reset(),
valid.render(),
valid.render_reset()
);
suggestions.push(styled_suggestion);
}
err = err
.extend_context_unchecked([(ContextKind::InvalidArg, ContextValue::String(arg))]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
match did_you_mean {
Some((flag, Some(sub))) => {
let mut styled_suggestion = StyledStr::new();
let _ = write!(
styled_suggestion,
"'{}{sub} {flag}{}' exists",
valid.render(),
valid.render_reset()
);
suggestions.push(styled_suggestion);
}
Some((flag, None)) => {
err = err.insert_context_unchecked(
ContextKind::SuggestedArg,
ContextValue::String(flag),
);
}
None => {}
}
if !suggestions.is_empty() {
err = err.insert_context_unchecked(
ContextKind::Suggested,
ContextValue::StyledStrs(suggestions),
);
}
}
err
}
pub(crate) fn unnecessary_double_dash(
cmd: &Command,
arg: String,
usage: Option<StyledStr>,
) -> Self {
use std::fmt::Write as _;
let styles = cmd.get_styles();
let invalid = &styles.get_invalid();
let valid = &styles.get_valid();
let mut err = Self::new(ErrorKind::UnknownArgument).with_cmd(cmd);
#[cfg(feature = "error-context")]
{
let mut styled_suggestion = StyledStr::new();
let _ = write!(
styled_suggestion,
"subcommand '{}{arg}{}' exists; to use it, remove the '{}--{}' before it",
valid.render(),
valid.render_reset(),
invalid.render(),
invalid.render_reset()
);
err = err.extend_context_unchecked([
(ContextKind::InvalidArg, ContextValue::String(arg)),
(
ContextKind::Suggested,
ContextValue::StyledStrs(vec![styled_suggestion]),
),
]);
if let Some(usage) = usage {
err = err
.insert_context_unchecked(ContextKind::Usage, ContextValue::StyledStr(usage));
}
}
err
}
fn formatted(&self) -> Cow<'_, StyledStr> {
if let Some(message) = self.inner.message.as_ref() {
message.formatted(&self.inner.styles)
} else {
let styled = F::format_error(self);
Cow::Owned(styled)
}
}
}
impl<F: ErrorFormatter> From<io::Error> for Error<F> {
fn from(e: io::Error) -> Self {
Error::raw(ErrorKind::Io, e)
}
}
impl<F: ErrorFormatter> From<fmt::Error> for Error<F> {
fn from(e: fmt::Error) -> Self {
Error::raw(ErrorKind::Format, e)
}
}
impl<F: ErrorFormatter> Debug for Error<F> {
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), fmt::Error> {
self.inner.fmt(f)
}
}
impl<F: ErrorFormatter> error::Error for Error<F> {
#[allow(trivial_casts)]
fn source(&self) -> Option<&(dyn error::Error + 'static)> {
self.inner.source.as_ref().map(|e| e.as_ref() as _)
}
}
impl<F: ErrorFormatter> Display for Error<F> {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
// Assuming `self.message` already has a trailing newline, from `try_help` or similar
ok!(write!(f, "{}", self.formatted()));
if let Some(backtrace) = self.inner.backtrace.as_ref() {
ok!(writeln!(f));
ok!(writeln!(f, "Backtrace:"));
ok!(writeln!(f, "{backtrace}"));
}
Ok(())
}
}
#[derive(Clone, Debug)]
pub(crate) enum Message {
Raw(String),
Formatted(StyledStr),
}
impl Message {
fn format(&mut self, cmd: &Command, usage: Option<StyledStr>) {
match self {
Message::Raw(s) => {
let mut message = String::new();
std::mem::swap(s, &mut message);
let styled = format::format_error_message(
&message,
cmd.get_styles(),
Some(cmd),
usage.as_ref(),
);
*self = Self::Formatted(styled);
}
Message::Formatted(_) => {}
}
}
fn formatted(&self, styles: &Styles) -> Cow<'_, StyledStr> {
match self {
Message::Raw(s) => {
let styled = format::format_error_message(s, styles, None, None);
Cow::Owned(styled)
}
Message::Formatted(s) => Cow::Borrowed(s),
}
}
}
impl From<String> for Message {
fn from(inner: String) -> Self {
Self::Raw(inner)
}
}
impl From<StyledStr> for Message {
fn from(inner: StyledStr) -> Self {
Self::Formatted(inner)
}
}
#[cfg(feature = "debug")]
#[derive(Debug)]
struct Backtrace(backtrace::Backtrace);
#[cfg(feature = "debug")]
impl Backtrace {
fn new() -> Option<Self> {
Some(Self(backtrace::Backtrace::new()))
}
}
#[cfg(feature = "debug")]
impl Display for Backtrace {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
// `backtrace::Backtrace` uses `Debug` instead of `Display`
write!(f, "{:?}", self.0)
}
}
#[cfg(not(feature = "debug"))]
#[derive(Debug)]
struct Backtrace;
#[cfg(not(feature = "debug"))]
impl Backtrace {
fn new() -> Option<Self> {
None
}
}
#[cfg(not(feature = "debug"))]
impl Display for Backtrace {
fn fmt(&self, _: &mut Formatter<'_>) -> fmt::Result {
Ok(())
}
}
#[test]
fn check_auto_traits() {
static_assertions::assert_impl_all!(Error: Send, Sync, Unpin);
}
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