You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: diagnostics.rs
    path of file: ./repos/c2rust/c2rust-transpile/src
    
    the code of the file until where you have to start completion: use colored::Colorize;
use failure::{err_msg, Backtrace, Context, Error, Fail};
use fern::colors::ColoredLevelConfig;
use log::{Level, SetLoggerError};
use std::collections::HashSet;
use std::fmt::{self, Display};
use std::io;
use std::str::FromStr;
use std::sync::Arc;
use strum_macros::{Display, EnumString};

use crate::c_ast::{ClangAstParseErrorKind, DisplaySrcSpan};
use c2rust_ast_exporter::get_clang_major_version;

const DEFAULT_WARNINGS: &[Diagnostic] = &[Diagnostic::ClangAst];

#[derive(PartialEq, Eq, Hash, Debug, Display, EnumString, Clone)]
#[strum(serialize_all = "kebab-case")]
pub enum Diagnostic {
    All,
    Comments,
    ClangAst,
}

macro_rules! diag {
    ($type:path, $($arg:tt)*) => (log::warn!(target: &$type.to_strin
    
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        use self::TranslationErrorKind::*;
        match self {
            Generic => {}

            OldLLVMSimd => {
                if let Some(version) = get_clang_major_version() {
                    if version < 7 {
                        return write!(f, "SIMD intrinsics require LLVM 7 or newer. Please build C2Rust against a newer LLVM version.");
                    }
                }
            }

            VaCopyNotImplemented => {
                return write!(f, "Rust does not yet support a C-compatible va_copy which is required to translate this function. See https://github.com/rust-lang/rust/pull/59625");
            }

            InvalidClangAst(_) => {
                return write!(f, "Exported Clang AST was invalid. Check warnings above for unimplemented features.");
            }
        }
        Ok(())
    }