syn#749 panic backtrace

stack backtrace:
   0: sqlx_macros::parse_as_ident::{{closure}}
             at sqlx-macros/src/lib.rs:144
   1: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:467
   2: rust_begin_unwind
             at src/libstd/panicking.rs:371
   3: std::panicking::begin_panic_fmt
             at src/libstd/panicking.rs:325
   4: rustc_expand::proc_macro_server::Ident::new
   5: <proc_macro::bridge::TokenTree<rustc_expand::proc_macro_server::Group,rustc_expand::proc_macro_server::Punct,rustc_expand::proc_macro_server::Ident,rustc_expand::proc_macro_server::Literal> as rustc_expand::proc_macro_server::FromInternal<((syntax::tokenstream::TokenTree, syntax::tokenstream::IsJoint), &rustc_session::parse::ParseSess, &mut alloc::vec::Vec<proc_macro::bridge::TokenTree<rustc_expand::proc_macro_server::Group,rustc_expand::proc_macro_server::Punct,rustc_expand::proc_macro_server::Ident,rustc_expand::proc_macro_server::Literal>>)>>::from_internal
   6: <rustc_expand::proc_macro_server::Rustc as proc_macro::bridge::server::TokenStreamIter>::next
   7: std::panicking::try::do_call
   8: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:79
   9: <proc_macro::bridge::server::Dispatcher<proc_macro::bridge::server::MarkedTypes<S>> as proc_macro::bridge::server::DispatcherTrait>::dispatch
  10: <proc_macro::bridge::closure::Closure<A,R> as core::convert::From<&mut F>>::from::call
  11: proc_macro::bridge::closure::Closure<A,R>::call
             at src/libproc_macro/bridge/closure.rs:27
      proc_macro::bridge::client::TokenStreamIter::next::{{closure}}
             at src/libproc_macro/bridge/client.rs:237
      proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::with::{{closure}}
             at src/libproc_macro/bridge/client.rs:321
      proc_macro::bridge::client::BridgeState::with::{{closure}}::{{closure}}
             at src/libproc_macro/bridge/client.rs:286
      proc_macro::bridge::scoped_cell::ScopedCell<T>::replace
             at src/libproc_macro/bridge/scoped_cell.rs:74
      proc_macro::bridge::client::BridgeState::with::{{closure}}
             at src/libproc_macro/bridge/client.rs:284
      std::thread::local::LocalKey<T>::try_with
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/thread/local.rs:262
      std::thread::local::LocalKey<T>::with
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/thread/local.rs:239
      proc_macro::bridge::client::BridgeState::with
             at src/libproc_macro/bridge/client.rs:283
      proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::with
             at src/libproc_macro/bridge/client.rs:314
      proc_macro::bridge::client::TokenStreamIter::next
             at src/libproc_macro/bridge/client.rs:230
      <proc_macro::token_stream::IntoIter as core::iter::traits::iterator::Iterator>::next
             at src/libproc_macro/lib.rs:199
  12: <proc_macro2::imp::TokenTreeIter as core::iter::traits::iterator::Iterator>::next
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/proc-macro2-1.0.7/src/wrapper.rs:337
  13: <proc_macro2::token_stream::IntoIter as core::iter::traits::iterator::Iterator>::next
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/proc-macro2-1.0.7/src/lib.rs:1178
  14: syn::buffer::TokenBuffer::inner_new
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-1.0.13/src/buffer.rs:55
  15: syn::buffer::TokenBuffer::new2
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-1.0.13/src/buffer.rs:114
  16: <F as syn::parse::Parser>::parse2
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-1.0.13/src/parse.rs:1146
  17: syn::parse::Parser::parse_str
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-1.0.13/src/parse.rs:1115
  18: syn::parse_str
             at /home/austin/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-1.0.13/src/lib.rs:885
  19: sqlx_macros::parse_as_ident
             at sqlx-macros/src/lib.rs:147
  20: core::ops::function::FnOnce::call_once
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libcore/ops/function.rs:232
  21: proc_macro::bridge::client::Client<fn(proc_macro::TokenStream) .> proc_macro::TokenStream>::expand1::run::{{closure}}
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:394
  22: proc_macro::bridge::client::run_client::{{closure}}::{{closure}}
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:362
  23: proc_macro::bridge::scoped_cell::ScopedCell<T>::set::{{closure}}
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/scoped_cell.rs:79
  24: proc_macro::bridge::scoped_cell::ScopedCell<T>::replace
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/scoped_cell.rs:74
  25: proc_macro::bridge::scoped_cell::ScopedCell<T>::set
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/scoped_cell.rs:79
  26: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter::{{closure}}
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:310
  27: std::thread::local::LocalKey<T>::try_with
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/thread/local.rs:262
  28: std::thread::local::LocalKey<T>::with
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/thread/local.rs:239
  29: proc_macro::bridge::client::<impl proc_macro::bridge::Bridge>::enter
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:310
  30: proc_macro::bridge::client::run_client::{{closure}}
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:355
  31: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/panic.rs:318
  32: std::panicking::try::do_call
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/panicking.rs:296
  33: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:79
  34: std::panicking::try
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/panicking.rs:272
  35: std::panic::catch_unwind
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libstd/panic.rs:394
  36: proc_macro::bridge::client::run_client
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:354
  37: proc_macro::bridge::client::Client<fn(proc_macro::TokenStream) .> proc_macro::TokenStream>::expand1::run
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/libproc_macro/bridge/client.rs:394
  38: proc_macro::bridge::server::run_server
  39: <rustc_expand::proc_macro::BangProcMacro as rustc_expand::base::ProcMacro>::expand
  40: rustc_expand::expand::MacroExpander::fully_expand_fragment
  41: rustc_expand::expand::MacroExpander::expand_crate
  42: rustc_session::utils::<impl rustc_session::session::Session>::time
  43: rustc_interface::passes::configure_and_expand_inner
  44: rustc_interface::passes::configure_and_expand::{{closure}}
  45: rustc_data_structures::box_region::PinnedGenerator<I,A,R>::new
  46: rustc_interface::passes::configure_and_expand
  47: rustc_interface::queries::Queries::expansion
  48: rustc_interface::interface::run_compiler_in_existing_thread_pool
  49: scoped_tls::ScopedKey<T>::set
  50: syntax::with_globals
  51: std::sys_common::backtrace::__rust_begin_short_backtrace
  52: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:79
  53: core::ops::function::FnOnce::call_once{{vtable.shim}}
  54: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/liballoc/boxed.rs:1015
  55: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/31dd4f4acbcbdb02b0745d2136399ed664a28050/src/liballoc/boxed.rs:1015
      std::sys_common::thread::start_thread
             at src/libstd/sys_common/thread.rs:13
      std::sys::unix::thread::Thread::new::thread_start
             at src/libstd/sys/unix/thread.rs:80
  56: start_thread
  57: clone