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use codespan_reporting::diagnostic::{Diagnostic, Label};
use codespan_reporting::files::SimpleFile;
use codespan_reporting::term::termcolor::StandardStream;
use codespan_reporting::term::{self, ColorArg};
use std::ops::Range;
use structopt::StructOpt;
#[derive(Debug, StructOpt)]
#[structopt(name = "emit")]
pub struct Opts {
#[structopt(long = "color",
parse(try_from_str),
default_value = "auto",
possible_values = ColorArg::VARIANTS,
case_insensitive = true
)]
color: ColorArg,
}
fn main() -> anyhow::Result<()> {
let file = SimpleFile::new(
"main.rs",
unindent::unindent(
r#"
fn main() {
let foo: i32 = "hello, world";
foo += 1;
}
"#,
),
);
let errors = [
Error::MismatchType(
Item::new(20..23, "i32"),
Item::new(31..45, "\"hello, world\""),
),
Error::MutatingImmutable(Item::new(20..23, "foo"), Item::new(51..59, "foo += 1")),
];
let opts = Opts::from_args();
let writer = StandardStream::stderr(opts.color.into());
let config = codespan_reporting::term::Config::default();
for diagnostic in errors.iter().map(Error::report) {
term::emit(&mut writer.lock(), &config, &file, &diagnostic)?;
}
Ok(())
}
/// An error enum that represent all possible errors within your program
enum Error {
MismatchType(Item, Item),
MutatingImmutable(Item, Item),
}
impl Error {
fn report(&self) -> Diagnostic<()> {
match self {
Error::MismatchType(left, right) => Diagnostic::error()
.with_code("E0308")
.with_message("mismatch types")
.with_labels(vec![
Label::primary((), right.range.clone()).with_message(format!(
"Expected `{}`, found: `{}`",
left.content, right.content,
)),
Label::secondary((), left.range.clone()).with_message("expected due to this"),
]),
Error::MutatingImmutable(original, mutating) => Diagnostic::error()
.with_code("E0384")
.with_message(format!(
"cannot mutate immutable variable `{}`",
original.content,
))
.with_labels(vec![
Label::secondary((), original.range.clone()).with_message(unindent::unindent(
&format!(
r#"
first assignment to `{0}`
help: make this binding mutable: `mut {0}`
"#,
original.content,
),
)),
Label::primary((), mutating.range.clone())
.with_message("cannot assign twice to immutable variable"),
]),
}
}
}
/// An item in the source code to be used in the `Error` enum.
/// In a more complex program it could also contain a `files::FileId` to handle errors that occur inside multiple files.
struct Item {
range: Range<usize>,
content: String,
}
impl Item {
fn new(range: Range<usize>, content: impl Into<String>) -> Item {
let content = content.into();
Item { range, content }
}
}