From b492d097e7dc1332c6de8c2edcc7888ef562d92d Mon Sep 17 00:00:00 2001
From: Wataru Otsubo <wataru.otsubo@cern.ch>
Date: Mon, 14 Apr 2025 07:27:15 +0000
Subject: [PATCH] Improve errormsg

---
 CHANGELOG.md     |  4 ++++
 src/generator.rs | 58 +++++++++++++++++++++++++++++-------------------
 2 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 317a18b..a155b60 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Packagin with Nix flakes (with nixpkgs buildRustPackage) [!16](https://gitlab.cern.ch/wotsubo/endcap-sl-software-ri-generator/-/merge_requests/16)
 - Now xml metadata can be overwritten with corresponding environmental variables. [!17](https://gitlab.cern.ch/wotsubo/endcap-sl-software-ri-generator/-/merge_requests/17)
 
+### Changed
+
+- Improve error message from syn in generator. !15
+
 ## [0.3.1] - 2025-04-11
 
 ### Changed
diff --git a/src/generator.rs b/src/generator.rs
index f4487b4..110e4f1 100644
--- a/src/generator.rs
+++ b/src/generator.rs
@@ -26,8 +26,12 @@ use thiserror::Error;
 
 #[derive(Debug, Error)]
 pub enum CodeGenError {
-    #[error("tokenization(syn) error")]
-    SynError(#[from] syn::Error),
+    #[error("tokenization(syn) error: {source}: {code}")]
+    SynError {
+        #[source]
+        source: syn::Error,
+        code: String,
+    },
     #[error("failed to create file (name duplicated): {0}")]
     FilePathDuplicatedError(String),
     #[error("parent is required for {module}")]
@@ -42,11 +46,17 @@ mod util {
     use super::CodeGenError;
 
     pub(super) fn parse_to_ident(s: &str) -> Result<proc_macro2::Ident, CodeGenError> {
-        Ok(syn::parse_str(s)?)
+        syn::parse_str(s).map_err(|e| CodeGenError::SynError {
+            source: e,
+            code: s.to_string(),
+        })
     }
 
     pub(super) fn parse_to_literal(s: &str) -> Result<proc_macro2::Literal, CodeGenError> {
-        Ok(syn::parse_str(s)?)
+        syn::parse_str(s).map_err(|e| CodeGenError::SynError {
+            source: e,
+            code: s.to_string(),
+        })
     }
 
     // currently only U32 is used, so `dead_code` for Debug, PartialEq
@@ -161,27 +171,29 @@ This code is auto generated using endcap_sl_software_ri_generator.
             GENERATOR_GIT_SHA,
         );
         let files = self.generate_register_interface(None, None, HashMap::new())?;
-        Ok(files
+        files
             .into_iter()
-            .map(
-                |(path, tokens)| -> Result<(PathBuf, syn::File), syn::Error> {
-                    let tokens = if path
-                        .file_name()
-                        .is_some_and(|file| file == "register_interface.rs")
-                    {
-                        quote! {
-                            #![doc = #build_metadata]
+            .map(|(path, tokens)| -> Result<(PathBuf, syn::File), _> {
+                let tokens = if path
+                    .file_name()
+                    .is_some_and(|file| file == "register_interface.rs")
+                {
+                    quote! {
+                        #![doc = #build_metadata]
 
-                            #tokens
-                        }
-                    } else {
-                        tokens
-                    };
-                    let file: syn::File = syn::parse2(tokens)?;
-                    Ok((path, file))
-                },
-            )
-            .process_results(|kv| HashMap::from_iter(kv))?)
+                        #tokens
+                    }
+                } else {
+                    tokens
+                };
+                let file: syn::File =
+                    syn::parse2(tokens.clone()).map_err(|e| CodeGenError::SynError {
+                        source: e,
+                        code: tokens.to_string(),
+                    })?;
+                Ok((path, file))
+            })
+            .process_results(|kv| HashMap::from_iter(kv))
     }
 }