proc macro server crashing due to corrupted `proc_macro::bridge::client::ProcMacro::Bang` name

[MoSal]

rustc 1.63.0-nightly (5435ed691 2022-06-07)
rust-analyzer 66a842124b52cb005e9dee4605df161badb295e0

Patch to see what's going on

 crates/proc-macro-srv/src/abis/abi_1_58/mod.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/crates/proc-macro-srv/src/abis/abi_1_58/mod.rs b/crates/proc-macro-srv/src/abis/abi_1_58/mod.rs
index dd3fd8b64..39d588657 100644
--- a/crates/proc-macro-srv/src/abis/abi_1_58/mod.rs
+++ b/crates/proc-macro-srv/src/abis/abi_1_58/mod.rs
@@ -86,6 +86,7 @@ impl Abi {
     }
 
     pub fn list_macros(&self) -> Vec<(String, ProcMacroKind)> {
+        eprintln!("exported_macros len={}", self.exported_macros.len());
         self.exported_macros
             .iter()
             .map(|proc_macro| match proc_macro {
@@ -93,6 +94,10 @@ impl Abi {
                     (trait_name.to_string(), ProcMacroKind::CustomDerive)
                 }
                 proc_macro::bridge::client::ProcMacro::Bang { name, .. } => {
+                    if name.len() > 1024 {
+                        eprintln!("mapping Bang name_len={}", name.len());
+                        eprintln!("mapping Bang name_start={:#?}", &name.as_bytes()[0..1024]);
+                    }
                     (name.to_string(), ProcMacroKind::FuncLike)
                 }
                 proc_macro::bridge::client::ProcMacro::Attr { name, .. } => {

What's going on

exported_macros len=4
mapping Bang name_len=140612842588360
mapping Bang name_start=[
[ERROR rust_analyzer::reload] proc macro server crashed: server exited

---

This is a serious regression in nightly and it's important to fix it before the next release.
@matklad, please take a look.

[bjorn3]

This is a serious regression in nightly and it's important to fix it before the next release.

This is caused by a change in rustc and not in rust-analyzer. There have been several changes in the proc macro abi last week: https://github.com/rust-lang/rust/commits/master/library/proc_macro Note that nightly rustc is not guaranteed to have working proc macros with rust-analyzer. Instead we handle it on a best-effort case for nightly. The proc macro abi is not stable and just an implementation detail of rustc. For this reason we have a copy of the proc macro server for every rustc version with a different proc macro abi.

@alexjg would you mind updating for the latest proc macro changes?

[MoSal]

@bjorn3 Thanks for the explanation.

The text you quoted comes from the issue template.

[bjorn3]

The text you quoted comes from the issue template.

I see. My bad.

[lnicola]

TBF, it's from the regression issue template 😄.

[alexjg]

I'm on holiday this week but should be able to sort this next week unless someone else gets there first

[bjorn3]

I'm going to give it a try then. Enjoy your holiday!

[bjorn3]

Opened #12492