Remove thiserror dependency from cranelift_codegen

cranelift/codegen/src/verifier/mod.rs

@@ -80,7 +80,6 @@ use alloc::vec::Vec;
 use core::cmp::Ordering;
 use core::fmt::{self, Display, Formatter, Write};
 use log::debug;
-use thiserror::Error;
 
 pub use self::cssa::verify_cssa;
 pub use self::liveness::verify_liveness;
@@ -92,8 +91,7 @@ mod liveness;
 mod locations;
 
 /// A verifier error.
-#[derive(Error, Debug, PartialEq, Eq, Clone)]
-#[error("{}{}: {}", .location, format_context(.context), .message)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub struct VerifierError {
     /// The entity causing the verifier error.
     pub location: AnyEntity,
@@ -104,11 +102,14 @@ pub struct VerifierError {
     pub message: String,
 }
 
-/// Helper for formatting Verifier::Error context.
-fn format_context(context: &Option<String>) -> String {
-    match context {
-        None => "".to_string(),
-        Some(c) => format!(" ({})", c),
+impl std::error::Error for VerifierError {}
+
+impl Display for VerifierError {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match &self.context {
+            None => write!(f, "{}: {}", self.location, self.message),
+            Some(context) => write!(f, "{} ({}): {}", self.location, context, self.message),
+        }
     }
 }
 
@@ -175,9 +176,11 @@ pub type VerifierStepResult<T> = Result<T, ()>;
 pub type VerifierResult<T> = Result<T, VerifierErrors>;
 
 /// List of verifier errors.
-#[derive(Error, Debug, Default, PartialEq, Eq, Clone)]
+#[derive(Debug, Default, PartialEq, Eq, Clone)]
 pub struct VerifierErrors(pub Vec<VerifierError>);
 
+impl std::error::Error for VerifierErrors {}
+
 impl VerifierErrors {
     /// Return a new `VerifierErrors` struct.
     #[inline]