Switch to using thiserror

cranelift/isle/Cargo.lock

@@ -72,6 +72,7 @@ name = "isle"
 version = "0.1.0"
 dependencies = [
  "log",
+ "thiserror",
 ]
 
 [[package]]
@@ -99,12 +100,41 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "proc-macro2"
+version = "1.0.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9f5105d4fdaab20335ca9565e106a5d9b82b6219b5ba735731124ac6711d23d"
+dependencies = [
+ "unicode-xid",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3d0b9745dc2debf507c8422de05d7226cc1f0644216dfdfead988f9b1ab32a7"
+dependencies = [
+ "proc-macro2",
+]
+
 [[package]]
 name = "strsim"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 
+[[package]]
+name = "syn"
+version = "1.0.77"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5239bc68e0fef57495900cfea4e8dc75596d9a319d7e16b1e0a440d24e6fe0a0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
 [[package]]
 name = "textwrap"
 version = "0.11.0"
@@ -114,12 +144,38 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "602eca064b2d83369e2b2f34b09c70b605402801927c65c11071ac911d299b88"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bad553cc2c78e8de258400763a647e80e6d1b31ee237275d756f6836d204494c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-width"
 version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
 
+[[package]]
+name = "unicode-xid"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
+
 [[package]]
 name = "vec_map"
 version = "0.8.2"

cranelift/isle/isle/Cargo.toml

@@ -7,3 +7,4 @@ license = "Apache-2.0 WITH LLVM-exception"
 
 [dependencies]
 log = "0.4"
+thiserror = "1.0.29"

cranelift/isle/isle/src/error.rs

@@ -1,12 +1,18 @@
 //! Error types.
 
+use std::sync::Arc;
+
 use crate::lexer::Pos;
-use std::fmt;
 
 /// Errors produced by ISLE.
-#[derive(Clone, Debug)]
+#[derive(thiserror::Error, Clone, Debug)]
 pub enum Error {
+    /// An I/O error.
+    #[error(transparent)]
+    IoError(Arc<std::io::Error>),
+
     /// The input ISLE source has an error.
+    #[error("{}:{}:{}: {}", .filename, .pos.line, .pos.col, .msg)]
     CompileError {
         /// The error message.
         msg: String,
@@ -15,43 +21,10 @@ pub enum Error {
         /// The position within the file that the error occurs at.
         pos: Pos,
     },
-    /// An error from elsewhere in the system.
-    SystemError {
-        /// The error message.
-        msg: String,
-    },
 }
 
-impl fmt::Display for Error {
+impl From<std::io::Error> for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn from(e: std::io::Error) -> Self {
-        match self {
+        Error::IoError(Arc::new(e))
-            &Error::CompileError {
-                ref msg,
-                ref filename,
-                pos,
-            } => {
-                write!(f, "{}:{}:{}: error: {}", filename, pos.line, pos.col, msg)
-            }
-            &Error::SystemError { ref msg } => {
-                write!(f, "{}", msg)
-            }
-        }
-    }
-}
-
-impl std::error::Error for Error {}
-
-impl std::convert::From<std::fmt::Error> for Error {
-    fn from(e: std::fmt::Error) -> Error {
-        Error::SystemError {
-            msg: format!("{}", e),
-        }
-    }
-}
-impl std::convert::From<std::io::Error> for Error {
-    fn from(e: std::io::Error) -> Error {
-        Error::SystemError {
-            msg: format!("{}", e),
-        }
     }
 }