feat(derive): Make `miette-derive` be able to be turned off (#304)

Cargo.toml

@@ -14,7 +14,7 @@ exclude = ["images/", "tests/", "miette-derive/"]
 
 [dependencies]
 thiserror = "1.0.40"
-miette-derive = { path = "miette-derive", version = "=5.10.0" }
+miette-derive = { path = "miette-derive", version = "=5.10.0", optional = true }
 once_cell = "1.8.0"
 unicode-width = "0.1.9"
 
@@ -44,7 +44,8 @@ lazy_static = "1.4"
 serde_json = "1.0.64"
 
 [features]
-default = []
+default = ["derive"]
+derive = ["miette-derive"]
 no-format-args-capture = []
 fancy-no-backtrace = [
     "owo-colors",

src/error.rs

@@ -1,27 +1,51 @@
-use std::io;
+use std::{fmt, io};
 
 use thiserror::Error;
 
-use crate::{self as miette, Diagnostic};
+use crate::Diagnostic;
 
 /**
 Error enum for miette. Used by certain operations in the protocol.
 */
-#[derive(Debug, Diagnostic, Error)]
+#[derive(Debug, Error)]
 pub enum MietteError {
     /// Wrapper around [`std::io::Error`]. This is returned when something went
     /// wrong while reading a [`SourceCode`](crate::SourceCode).
     #[error(transparent)]
-    #[diagnostic(code(miette::io_error), url(docsrs))]
     IoError(#[from] io::Error),
 
     /// Returned when a [`SourceSpan`](crate::SourceSpan) extends beyond the
     /// bounds of a given [`SourceCode`](crate::SourceCode).
     #[error("The given offset is outside the bounds of its Source")]
-    #[diagnostic(
-        code(miette::span_out_of_bounds),
-        help("Double-check your spans. Do you have an off-by-one error?"),
-        url(docsrs)
-    )]
     OutOfBounds,
 }
+
+impl Diagnostic for MietteError {
+    fn code<'a>(&'a self) -> Option<Box<dyn fmt::Display + 'a>> {
+        match self {
+            MietteError::IoError(_) => Some(Box::new("miette::io_error")),
+            MietteError::OutOfBounds => Some(Box::new("miette::span_out_of_bounds")),
+        }
+    }
+
+    fn help<'a>(&'a self) -> Option<Box<dyn fmt::Display + 'a>> {
+        match self {
+            MietteError::IoError(_) => None,
+            MietteError::OutOfBounds => Some(Box::new(
+                "Double-check your spans. Do you have an off-by-one error?",
+            )),
+        }
+    }
+
+    fn url<'a>(&'a self) -> Option<Box<dyn fmt::Display + 'a>> {
+        let crate_version = env!("CARGO_PKG_VERSION");
+        let variant = match self {
+            MietteError::IoError(_) => "#variant.IoError",
+            MietteError::OutOfBounds => "#variant.OutOfBounds",
+        };
+        Some(Box::new(format!(
+            "https://docs.rs/miette/{}/miette/enum.MietteError.html{}",
+            crate_version, variant,
+        )))
+    }
+}

src/lib.rs

@@ -652,6 +652,7 @@
 //! and some from [`thiserror`](https://github.com/dtolnay/thiserror), also
 //! under the Apache License. Some code is taken from
 //! [`ariadne`](https://github.com/zesterer/ariadne), which is MIT licensed.
+#[cfg(feature = "derive")]
 pub use miette_derive::*;
 
 pub use error::*;