third_party/rust_crates/vendor/anyhow/src/fmt.rs

use crate::chain::Chain;
use crate::error::ErrorImpl;
use core::fmt::{self, Debug};

impl ErrorImpl<()> {
    pub(crate) fn display(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.error())?;

        if f.alternate() {
            for cause in self.chain().skip(1) {
                write!(f, ": {}", cause)?;
            }
        }

        Ok(())
    }

    pub(crate) fn debug(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let error = self.error();

        if f.alternate() {
            return Debug::fmt(error, f);
        }

        write!(f, "{}", error)?;

        if let Some(cause) = error.source() {
            write!(f, "\n\nCaused by:")?;
            let multiple = cause.source().is_some();
            for (n, error) in Chain::new(cause).enumerate() {
                write!(f, "\n    ")?;
                if multiple {
                    write!(f, "{}: ", n)?;
                }
                write!(f, "{}", error)?;
            }
        }

        #[cfg(backtrace)]
        {
            use std::backtrace::BacktraceStatus;

            let backtrace = self.backtrace();
            if let BacktraceStatus::Captured = backtrace.status() {
                let mut backtrace = backtrace.to_string();
                if backtrace.starts_with("stack backtrace:") {
                    // Capitalize to match "Caused by:"
                    backtrace.replace_range(0..1, "S");
                }
                backtrace.truncate(backtrace.trim_end().len());
                write!(f, "\n\n{}", backtrace)?;
            }
        }

        Ok(())
    }
}