From dd22d7a1649964e92c5041417df1d21bf50d2858 Mon Sep 17 00:00:00 2001
From: Bradlee Speice <bradlee@speice.io>
Date: Mon, 30 Dec 2024 18:48:19 -0500
Subject: [PATCH] Implement standard errors

---
 Cargo.lock           | 21 +++++++++++++++++++++
 Cargo.toml           |  1 +
 slang-sys/build.rs   |  1 +
 slang-sys/src/lib.rs | 12 +++++++++++-
 src/lib.rs           | 36 ++++++++++++++++++++++--------------
 5 files changed, 56 insertions(+), 15 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 108f7a8..16c7ad2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -220,6 +220,7 @@ name = "slang"
 version = "0.1.0"
 dependencies = [
  "slang-sys",
+ "thiserror",
 ]
 
 [[package]]
@@ -241,6 +242,26 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "thiserror"
+version = "2.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f072643fd0190df67a8bab670c20ef5d8737177d6ac6b2e9a236cb096206b2cc"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "2.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b50fa271071aae2e6ee85f842e2e28ba8cd2c5fb67f11fcb1fd70b276f9e7d4"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.14"
diff --git a/Cargo.toml b/Cargo.toml
index 66858b5..9c2e1af 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,6 +7,7 @@ publish = false
 
 [dependencies]
 slang-sys = { path = "slang-sys" }
+thiserror = "2.0"
 
 [workspace]
 members = [
diff --git a/slang-sys/build.rs b/slang-sys/build.rs
index 4391ba8..e621d94 100644
--- a/slang-sys/build.rs
+++ b/slang-sys/build.rs
@@ -54,6 +54,7 @@ fn main() {
 		})
 		.constified_enum("SlangProfileID")
 		.constified_enum("SlangCapabilityID")
+		.new_type_alias("SlangResult")
 		.vtable_generation(true)
 		.layout_tests(false)
 		.derive_copy(true)
diff --git a/slang-sys/src/lib.rs b/slang-sys/src/lib.rs
index 9d1e596..38ce9e6 100644
--- a/slang-sys/src/lib.rs
+++ b/slang-sys/src/lib.rs
@@ -3,7 +3,7 @@
 include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
 
 use std::ffi::{c_char, c_int, c_void};
-
+use std::fmt::{Display, Formatter};
 // Based on Slang version 2024.14.5
 
 #[repr(C)]
@@ -135,3 +135,13 @@ pub struct IModuleVtable {
 	pub getDependencyFilePath: unsafe extern "C" fn(*mut c_void, index: SlangInt32) -> *const c_char,
 	pub getModuleReflection: unsafe extern "C" fn(*mut c_void) -> *mut slang_DeclReflection,
 }
+
+impl Display for SlangResult {
+	fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+		if self.0 > 0 {
+			write!(f, "success")
+		} else {
+			write!(f, "failure")
+		}
+	}
+}
diff --git a/src/lib.rs b/src/lib.rs
index da3a3c7..e1ac5e8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 pub mod reflection;
 
 use std::ffi::{CStr, CString};
+use std::fmt::{Debug, Display, Formatter};
 use std::ptr::{null, null_mut};
 
 use slang_sys as sys;
@@ -29,33 +30,28 @@ const fn uuid(data1: u32, data2: u16, data3: u16, data4: [u8; 8]) -> UUID {
 	}
 }
 
+#[derive(thiserror::Error, Debug)]
 pub enum Error {
-	Code(sys::SlangResult),
-	Blob(Blob),
-}
+	#[error("underlying library error: `{0}`")]
+	Slang(sys::SlangResult),
 
-impl std::fmt::Debug for Error {
-	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-		match self {
-			Error::Code(code) => write!(f, "{}", code),
-			Error::Blob(blob) => write!(f, "{}", blob.as_str().unwrap()),
-		}
-	}
+	#[error("blob")]
+	Blob(Blob),
 }
 
 pub type Result<T> = std::result::Result<T, Error>;
 
 pub(crate) fn succeeded(result: sys::SlangResult) -> bool {
-	result >= 0
+	result.0 >= 0
 }
 
 fn result_from_blob(code: sys::SlangResult, blob: *mut sys::slang_IBlob) -> Result<()> {
-	if code < 0 {
+	if succeeded(code) {
+		Ok(())
+	} else {
 		Err(Error::Blob(Blob(IUnknown(
 			std::ptr::NonNull::new(blob as *mut _).unwrap(),
 		))))
-	} else {
-		Ok(())
 	}
 }
 
@@ -125,6 +121,18 @@ impl Drop for IUnknown {
 #[derive(Clone)]
 pub struct Blob(IUnknown);
 
+impl Debug for Blob {
+	fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+		write!(f, "ptr={:p}", self.0.0)
+	}
+}
+
+impl Display for Blob {
+	fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+		Debug::fmt(&self, f)
+	}
+}
+
 unsafe impl Interface for Blob {
 	type Vtable = sys::IBlobVtable;
 	const IID: UUID = uuid(