range end index 4 out of range for slice of length 0 - rust-analyzer macro-error

[aminya]

I am getting this strange error from the rust analyzer:

range end index 4 out of range for slice of length 0 rust-analyzer [macro-error](https://rust-analyzer.github.io/manual.html#macro-error)

I just added the #memoize config before a function like this:

#[memoize]
pub fn do_something(path1: PathBuf, path2: PathBuf) -> String {
  // ...
}

Full backtrace:

thread '<unnamed>' panicked at 'range end index 4 out of range for slice of length 0', library\core\src\slice\index.rs:73:5
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509/library\std\src\panicking.rs:584
   1: core::panicking::panic_fmt
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509/library\core\src\panicking.rs:142
   2: core::slice::index::slice_end_index_len_fail_rt
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509/library\core\src\slice\index.rs:73
   3: core::ops::function::FnOnce::call_once<never$ (*)(usize,usize),tuple$<usize,usize> >
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509/library\core\src\ops\function.rs:248
   4: core::intrinsics::const_eval_select<tuple$<usize,usize>,never$ (*)(usize,usize),never$ (*)(usize,usize),never$>
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509/library\core\src\intrinsics.rs:2695
   5: core::slice::index::slice_end_index_len_fail
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509/library\core\src\slice\index.rs:67
   6: core::slice::index::impl$3::index<u8>
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\core\src\slice\index.rs:304
   7: core::slice::index::impl$0::index
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\core\src\slice\index.rs:18
   8: proc_macro::bridge::rpc::impl$26::decode<tuple$<> >
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\rpc.rs:38
   9: proc_macro::bridge::rpc::impl$9::decode<tuple$<> >
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\rpc.rs:169
  10: proc_macro::bridge::client::impl$79::decode<tuple$<> >
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\client.rs:166
  11: proc_macro::bridge::impl$81::decode<tuple$<>,proc_macro::bridge::client::Span>
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\rpc.rs:57
  12: proc_macro::bridge::rpc::impl$11::decode<tuple$<>,proc_macro::bridge::ExpnGlobals<proc_macro::bridge::client::Span>,tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream> >
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\rpc.rs:184
  13: proc_macro::bridge::client::run_client::closure$0<tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream>,enum$<core::option::Option<proc_macro::bridge::client::TokenStream>, 1, 4294967295, Some>,proc_macro::bridge::client:
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\client.rs:409
  14: core::panic::unwind_safe::impl$23::call_once<tuple$<>,proc_macro::bridge::client::run_client::closure_env$0<tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream>,enum$<core::option::Option<proc_macro::bridge::client::Toke
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\core\src\panic\unwind_safe.rs:271
  15: std::panicking::try::do_call<core::panic::unwind_safe::AssertUnwindSafe<proc_macro::bridge::client::run_client::closure_env$0<tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream>,enum$<core::option::Option<proc_macro::br
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\std\src\panicking.rs:492
  16: proc_macro2::impl$44::clone
  17: std::panicking::try<tuple$<>,core::panic::unwind_safe::AssertUnwindSafe<proc_macro::bridge::client::run_client::closure_env$0<tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream>,enum$<core::option::Option<proc_macro::br
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\std\src\panicking.rs:456
  18: std::panic::catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<proc_macro::bridge::client::run_client::closure_env$0<tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream>,enum$<core::option::Option<proc_macro::bridge
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\std\src\panic.rs:137
  19: proc_macro::bridge::client::run_client<tuple$<proc_macro::bridge::client::TokenStream,proc_macro::bridge::client::TokenStream>,enum$<core::option::Option<proc_macro::bridge::client::TokenStream>, 1, 4294967295, Some>,proc_macro::bridge::client::impl$14::e
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\client.rs:405
  20: proc_macro::bridge::client::impl$14::expand2::closure$0<proc_macro::TokenStream (*)(proc_macro::TokenStream,proc_macro::TokenStream)>
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\client.rs:463
  21: proc_macro::bridge::selfless_reify::reify_to_extern_c_fn_hrt_bridge::wrapper<proc_macro::bridge::buffer::Buffer,proc_macro::bridge::client::impl$14::expand2::closure_env$0<proc_macro::TokenStream (*)(proc_macro::TokenStream,proc_macro::TokenStream)> >
             at /rustc/6dba4ed215e7a60f0a2a19c04f3f73691f89c509\library\proc_macro\src\bridge\selfless_reify.rs:64
  22: ZN14proc_macro_srv4abis8abi_1_6310proc_macro6bridge6server271_$LT$impl$u20$proc_macro_srv..abis..abi_1_63..proc_macro..bridge..client..Client$LT$$LP$proc_macro_srv..abis..abi_1_63..proc_macro..TokenStream$C$proc_macro_srv..abis..abi_1_63..proc_macro..Toke
  23: proc_macro_srv::abis::abi_1_63::Abi::expand
  24: proc_macro_srv::abis::Abi::expand
  25: proc_macro_srv::dylib::Expander::expand
  26: proc_macro_srv::ProcMacroSrv::expand
  27: proc_macro_srv::cli::run
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[dermesser]

Thank you! I created an example from this locally, and it compiles (which it does for you too, I understand?). However, in my neovim/rust-analyzer (rust-analyzer 0.0.0 (ec78b6b08 2022-07-01) as well as 5342f47f4 2022-07-09) setup I don't see this error. Do you have a specific setup?

[aminya]

Thanks for checking this. I think this is a bug in the rust-analyzer itself. It also happens with some other attributes! I should report this to the rust analyzer itself. I use the rust analyzer nightly in VsCode, so it could be it.

rust-lang/rust-analyzer#12780