From 313c8295e5d1ea01c6d4efb8584da727e37e97ef Mon Sep 17 00:00:00 2001
From: Aarni Koskela <akx@iki.fi>
Date: Mon, 25 Aug 2025 11:30:56 +0300
Subject: [PATCH] Use thiserror

---
 Cargo.lock | 21 +++++++++++++++++++++
 Cargo.toml |  3 ++-
 src/lib.rs | 25 +++++++------------------
 3 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index d592cb6..24f8554 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -320,6 +320,7 @@ dependencies = [
  "half",
  "memmap2",
  "tempfile",
+ "thiserror",
 ]
 
 [[package]]
@@ -534,6 +535,26 @@ dependencies = [
  "windows-sys 0.59.0",
 ]
 
+[[package]]
+name = "thiserror"
+version = "2.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3467d614147380f2e4e374161426ff399c91084acd2363eaf549172b3d5e60c0"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "2.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c5e1be1c48b9172ee610da68fd9cd2770e7a4056cb3fc98710ee6906f0c7960"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "tinytemplate"
 version = "1.2.1"
diff --git a/Cargo.toml b/Cargo.toml
index 6a66fb9..f143e64 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,7 @@ readme = "README.md"
 [dependencies]
 bytemuck = { version = "1.15", default-features = false, features = ["derive"] }
 memmap2 = { version = "0.9", optional = true }
+thiserror = { version = "2.0.16", default-features = false }
 
 [dev-dependencies]
 criterion = { version = "0.5", features = ["html_reports"] }
@@ -49,5 +50,5 @@ harness = false
 default = ["std", "mmap", "file"]
 mmap = ["std", "dep:memmap2"]
 file = ["std"]
-std = []
+std = ["thiserror/std"]
 f16 = []
diff --git a/src/lib.rs b/src/lib.rs
index d0040bf..018a95b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -30,30 +30,19 @@ pub use mrcfile::{MrcFile, open_file};
 
 // Error type
 
-#[derive(Debug)]
+#[derive(thiserror::Error, Debug)]
 pub enum Error {
+    #[error("IO error")]
     Io,
+    #[error("Invalid MRC header")]
     InvalidHeader,
+    #[error("Invalid MRC mode")]
     InvalidMode,
+    #[error("Invalid dimensions")]
     InvalidDimensions,
+    #[error("Type mismatch")]
     TypeMismatch,
     #[cfg(feature = "mmap")]
+    #[error("Memory mapping error")]
     Mmap,
 }
-
-impl core::fmt::Display for Error {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        match self {
-            Error::Io => write!(f, "IO error"),
-            Error::InvalidHeader => write!(f, "Invalid MRC header"),
-            Error::InvalidMode => write!(f, "Invalid MRC mode"),
-            Error::InvalidDimensions => write!(f, "Invalid dimensions"),
-            Error::TypeMismatch => write!(f, "Type mismatch"),
-            #[cfg(feature = "mmap")]
-            Error::Mmap => write!(f, "Memory mapping error"),
-        }
-    }
-}
-
-#[cfg(feature = "std")]
-impl core::error::Error for Error {}