From 82f3ad4f1a412ae94958bb5eb82788bc95082b2a Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Fri, 19 Mar 2021 16:41:39 +0100
Subject: [PATCH] Add comment why thiserror is not used

---
 cranelift/codegen/src/data_value.rs         | 2 ++
 cranelift/codegen/src/isa/mod.rs            | 2 ++
 cranelift/codegen/src/isa/unwind/systemv.rs | 2 ++
 cranelift/codegen/src/result.rs             | 2 ++
 cranelift/codegen/src/verifier/mod.rs       | 4 ++++
 cranelift/module/src/module.rs              | 2 ++
 6 files changed, 14 insertions(+)

diff --git a/cranelift/codegen/src/data_value.rs b/cranelift/codegen/src/data_value.rs
index 8819859f09..a317c7f394 100644
--- a/cranelift/codegen/src/data_value.rs
+++ b/cranelift/codegen/src/data_value.rs
@@ -103,6 +103,8 @@ pub enum DataValueCastFailure {
     FromInteger(i64, Type),
 }
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for DataValueCastFailure {}
 
 impl Display for DataValueCastFailure {
diff --git a/cranelift/codegen/src/isa/mod.rs b/cranelift/codegen/src/isa/mod.rs
index 811ad8c9d7..fccb46f7a6 100644
--- a/cranelift/codegen/src/isa/mod.rs
+++ b/cranelift/codegen/src/isa/mod.rs
@@ -186,6 +186,8 @@ pub enum LookupError {
     Unsupported,
 }
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for LookupError {}
 
 impl fmt::Display for LookupError {
diff --git a/cranelift/codegen/src/isa/unwind/systemv.rs b/cranelift/codegen/src/isa/unwind/systemv.rs
index 9e537907a8..da3bfea869 100644
--- a/cranelift/codegen/src/isa/unwind/systemv.rs
+++ b/cranelift/codegen/src/isa/unwind/systemv.rs
@@ -21,6 +21,8 @@ pub enum RegisterMappingError {
     UnsupportedRegisterBank(&'static str),
 }
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for RegisterMappingError {}
 
 impl std::fmt::Display for RegisterMappingError {
diff --git a/cranelift/codegen/src/result.rs b/cranelift/codegen/src/result.rs
index aa264c7601..3178cd5ba9 100644
--- a/cranelift/codegen/src/result.rs
+++ b/cranelift/codegen/src/result.rs
@@ -41,6 +41,8 @@ pub enum CodegenError {
 /// A convenient alias for a `Result` that uses `CodegenError` as the error type.
 pub type CodegenResult<T> = Result<T, CodegenError>;
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for CodegenError {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match self {
diff --git a/cranelift/codegen/src/verifier/mod.rs b/cranelift/codegen/src/verifier/mod.rs
index 7c64c0464c..1d1801016b 100644
--- a/cranelift/codegen/src/verifier/mod.rs
+++ b/cranelift/codegen/src/verifier/mod.rs
@@ -102,6 +102,8 @@ pub struct VerifierError {
     pub message: String,
 }
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for VerifierError {}
 
 impl Display for VerifierError {
@@ -179,6 +181,8 @@ pub type VerifierResult<T> = Result<T, VerifierErrors>;
 #[derive(Debug, Default, PartialEq, Eq, Clone)]
 pub struct VerifierErrors(pub Vec<VerifierError>);
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for VerifierErrors {}
 
 impl VerifierErrors {
diff --git a/cranelift/module/src/module.rs b/cranelift/module/src/module.rs
index 97db899342..191d468ed7 100644
--- a/cranelift/module/src/module.rs
+++ b/cranelift/module/src/module.rs
@@ -192,6 +192,8 @@ pub enum ModuleError {
     Backend(anyhow::Error),
 }
 
+// This is manually implementing Error and Display instead of using thiserror to reduce the amount
+// of dependencies used by Cranelift.
 impl std::error::Error for ModuleError {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match self {