From 50e2330dce8a9d7a9adfeee2c219fc00487b4dbd Mon Sep 17 00:00:00 2001
From: bit-aloo <sshourya17@gmail.com>
Date: Sun, 11 Jan 2026 18:27:30 +0530
Subject: [PATCH] add suggested changes:  have a internal error variant,
 comment on unwindsafe

---
 .../src/bidirectional_protocol.rs             |  2 ++
 .../proc-macro-srv-cli/src/main_loop.rs       | 12 ++++++---
 .../crates/proc-macro-srv/src/lib.rs          | 25 +++++++++++++------
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/tools/rust-analyzer/crates/proc-macro-api/src/bidirectional_protocol.rs b/src/tools/rust-analyzer/crates/proc-macro-api/src/bidirectional_protocol.rs
index ffdc6fdd4dec..ba59cb219b9a 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-api/src/bidirectional_protocol.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-api/src/bidirectional_protocol.rs
@@ -56,6 +56,8 @@ pub fn run_conversation(
                 return Ok(BidirectionalMessage::Response(response));
             }
             BidirectionalMessage::SubRequest(sr) => {
+                // TODO: Avoid `AssertUnwindSafe` by making the callback `UnwindSafe` once `ExpandDatabase`
+                // becomes unwind-safe (currently blocked by `parking_lot::RwLock` in the VFS).
                 let resp = match catch_unwind(AssertUnwindSafe(|| callback(sr))) {
                     Ok(Ok(resp)) => BidirectionalMessage::SubResponse(resp),
                     Ok(Err(err)) => BidirectionalMessage::SubResponse(SubResponse::Cancel {
diff --git a/src/tools/rust-analyzer/crates/proc-macro-srv-cli/src/main_loop.rs b/src/tools/rust-analyzer/crates/proc-macro-srv-cli/src/main_loop.rs
index af8c3cb39ba2..c19847b4b53d 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-srv-cli/src/main_loop.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-srv-cli/src/main_loop.rs
@@ -11,7 +11,7 @@ use std::{
 
 use legacy::Message;
 
-use proc_macro_srv::{EnvSnapshot, ProcMacroCancelMarker, ProcMacroClientError, SpanId};
+use proc_macro_srv::{EnvSnapshot, ProcMacroClientError, ProcMacroPanicMarker, SpanId};
 
 struct SpanTrans;
 
@@ -199,13 +199,17 @@ impl<'a> ProcMacroClientHandle<'a> {
 fn handle_failure(failure: Result<bidirectional::SubResponse, ProcMacroClientError>) -> ! {
     match failure {
         Err(ProcMacroClientError::Cancelled { reason }) => {
-            panic_any(ProcMacroCancelMarker { reason });
+            panic_any(ProcMacroPanicMarker::Cancelled { reason });
         }
         Err(err) => {
-            panic!("proc-macro IPC failed: {err:?}");
+            panic_any(ProcMacroPanicMarker::Internal {
+                reason: format!("proc-macro IPC error: {err:?}"),
+            });
         }
         Ok(other) => {
-            panic!("unexpected SubResponse {other:?}");
+            panic_any(ProcMacroPanicMarker::Internal {
+                reason: format!("unexpected SubResponse {other:?}"),
+            });
         }
     }
 }
diff --git a/src/tools/rust-analyzer/crates/proc-macro-srv/src/lib.rs b/src/tools/rust-analyzer/crates/proc-macro-srv/src/lib.rs
index 0462aafd00e7..c548dc620ad1 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-srv/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-srv/src/lib.rs
@@ -105,8 +105,9 @@ pub enum ProcMacroClientError {
 }
 
 #[derive(Debug)]
-pub struct ProcMacroCancelMarker {
-    pub reason: String,
+pub enum ProcMacroPanicMarker {
+    Cancelled { reason: String },
+    Internal { reason: String },
 }
 
 pub type ProcMacroClientHandle<'a> = &'a mut (dyn ProcMacroClientInterface + Sync + Send);
@@ -126,6 +127,7 @@ const EXPANDER_STACK_SIZE: usize = 8 * 1024 * 1024;
 pub enum ExpandError {
     Panic(PanicMessage),
     Cancelled { reason: Option<String> },
+    Internal { reason: Option<String> },
 }
 
 impl ExpandError {
@@ -133,6 +135,7 @@ impl ExpandError {
         match self {
             ExpandError::Panic(panic_message) => panic_message.into_string(),
             ExpandError::Cancelled { reason } => reason,
+            ExpandError::Internal { reason } => reason,
         }
     }
 }
@@ -152,10 +155,8 @@ impl ProcMacroSrv<'_> {
         callback: Option<ProcMacroClientHandle<'_>>,
     ) -> Result<token_stream::TokenStream<S>, ExpandError> {
         let snapped_env = self.env;
-        let expander = self.expander(lib.as_ref()).map_err(|err| {
-            ExpandError::Panic(PanicMessage {
-                message: Some(format!("failed to load macro: {err}")),
-            })
+        let expander = self.expander(lib.as_ref()).map_err(|err| ExpandError::Internal {
+            reason: Some(format!("failed to load macro: {err}")),
         })?;
 
         let prev_env = EnvChange::apply(snapped_env, env, current_dir.as_ref().map(<_>::as_ref));
@@ -176,9 +177,17 @@ impl ProcMacroSrv<'_> {
                 Ok(res) => res.map_err(ExpandError::Panic),
 
                 Err(payload) => {
-                    if let Some(cancel) = payload.downcast_ref::<ProcMacroCancelMarker>() {
-                        return Err(ExpandError::Cancelled { reason: Some(cancel.reason.clone()) });
+                    if let Some(marker) = payload.downcast_ref::<ProcMacroPanicMarker>() {
+                        return match marker {
+                            ProcMacroPanicMarker::Cancelled { reason } => {
+                                Err(ExpandError::Cancelled { reason: Some(reason.clone()) })
+                            }
+                            ProcMacroPanicMarker::Internal { reason } => {
+                                Err(ExpandError::Internal { reason: Some(reason.clone()) })
+                            }
+                        };
                     }
+
                     std::panic::resume_unwind(payload)
                 }
             }