Proc macro attribute with raw identifier causes ICE

[emmatyping]

Code

I have created the following repository with a minimal as I could think of reproduction of the ICE:

https://github.com/ethanhs/Rust-ICE-repro

This was discovered in the wild a while ago (I wanted to reduce it before reporting, sorry for the delay). PyO3/pyo3#743

Meta

I used the latest nightly version of rustc

rustc --version --verbose:

rustc 1.44.0-nightly (dbf8b6bf1 2020-04-19)
binary: rustc
commit-hash: dbf8b6bf116c7bece2987ff4bd2792f008a6ee77
commit-date: 2020-04-19
host: x86_64-pc-windows-msvc
release: 1.44.0-nightly
LLVM version: 9.0

Error output

   Compiling ex v0.1.0 (C:\Users\ethanhs\proctest\ex)
   Compiling proctest v0.1.0 (C:\Users\ethanhs\proctest)
thread 'rustc' panicked at '`"set_r#raw"` is not a valid identifier', src\librustc_expand\proc_macro_server.rs:329:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (dbf8b6bf1 2020-04-19) running on x86_64-pc-windows-msvc

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

error: custom attribute panicked
 --> src\main.rs:2:1
  |
2 | #[hello]
  | ^^^^^^^^
  |
  = help: message: `"set_r#raw"` is not a valid identifier

error: aborting due to previous error

error: could not compile `proctest`.

To learn more, run the command again with --verbose.

Backtrace

   Compiling proctest v0.1.0 (C:\Users\ethanhs\proctest)
thread 'rustc' panicked at '`"set_r#raw"` is not a valid identifier', src\librustc_expand\proc_macro_server.rs:329:13
stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: <std::io::IoSlice as core::fmt::Debug>::fmt
   3: std::panicking::take_hook
   4: std::panicking::take_hook
   5: rustc_driver::report_ice
   6: std::panicking::rust_panic_with_hook
   7: rust_begin_unwind
   8: std::panicking::begin_panic_fmt
   9: rustc_expand::expand::AstFragment::make_variants
  10: <rustc_expand::config::StripUnconfigured as rustc_ast::mut_visit::MutVisitor>::visit_fn_decl
  11: <rustc_expand::mbe::TokenTree as core::fmt::Debug>::fmt
  12: <rustc_expand::mbe::TokenTree as core::fmt::Debug>::fmt
  13: proc_macro::bridge::scoped_cell::ScopedCell::replace
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\/src\libproc_macro\bridge\scoped_cell.rs:74
  14: proc_macro::bridge::client::{{impl}}::with::{{closure}}
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\/src\libproc_macro\bridge\client.rs:284
  15: std::thread::local::LocalKey::try_with
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\src\libstd\thread\local.rs:263
  16: std::thread::local::LocalKey::with
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\src\libstd\thread\local.rs:239
  17: proc_macro::bridge::client::BridgeState::with
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\/src\libproc_macro\bridge\client.rs:283
  18: proc_macro::bridge::Bridge::with
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\/src\libproc_macro\bridge\client.rs:314
  19: proc_macro::bridge::client::Ident::new
             at /rustc/dbf8b6bf116c7bece2987ff4bd2792f008a6ee77\/src\libproc_macro\bridge\client.rs:230
  20: ex::hello
             at .\ex\src\lib.rs:5
  21: core::ops::function::FnOnce::call_once<fn(proc_macro::TokenStream, proc_macro::TokenStream) -> proc_macro::TokenStream,(proc_macro::TokenStream, proc_macro::TokenStream)>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libcore\ops\function.rs:232
  22: proc_macro::bridge::client::{{impl}}::expand2::run::{{closure}}<fn(proc_macro::TokenStream, proc_macro::TokenStream) -> proc_macro::TokenStream>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:409
  23: proc_macro::bridge::client::run_client::{{closure}}::{{closure}}<(proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::TokenStream),proc_macro::bridge::client
::TokenStream,closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:362
  24: proc_macro::bridge::scoped_cell::{{impl}}::set::{{closure}}<proc_macro::bridge::client::BridgeStateL,(),closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\scoped_cell.rs:79
  25: proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>::replace<proc_macro::bridge::client::BridgeStateL,(),closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\scoped_cell.rs:74
  26: proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>::set<proc_macro::bridge::client::BridgeStateL,(),closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\scoped_cell.rs:79
  27: proc_macro::bridge::client::{{impl}}::enter::{{closure}}<(),closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:310
  28: std::thread::local::LocalKey<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>>::try_with<proc_macro::bridge::scoped_cell::ScopedCell<proc
_macro::bridge::client::BridgeStateL>,closure-1,()>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\thread\local.rs:263
  29: std::thread::local::LocalKey<proc_macro::bridge::scoped_cell::ScopedCell<proc_macro::bridge::client::BridgeStateL>>::with<proc_macro::bridge::scoped_cell::ScopedCell<proc_mac
ro::bridge::client::BridgeStateL>,closure-1,()>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\thread\local.rs:239
  30: proc_macro::bridge::Bridge::enter<(),closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:310
  31: proc_macro::bridge::client::run_client::{{closure}}<(proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::TokenStream),proc_macro::bridge::client::TokenStream
,closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:355
  32: std::panic::{{impl}}::call_once<(),closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\panic.rs:318
  33: std::panicking::try::do_call<std::panic::AssertUnwindSafe<closure-0>,()>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\panicking.rs:331
  34: std::panicking::begin_panic::{{impl}}::take_box<str*>
  35: std::panicking::try<(),std::panic::AssertUnwindSafe<closure-0>>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\panicking.rs:274
  36: std::panic::catch_unwind<std::panic::AssertUnwindSafe<closure-0>,()>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libstd\panic.rs:394
  37: proc_macro::bridge::client::run_client<(proc_macro::bridge::client::TokenStream, proc_macro::bridge::client::TokenStream),proc_macro::bridge::client::TokenStream,closure-0>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:354
  38: proc_macro::bridge::client::{{impl}}::expand2::run<fn(proc_macro::TokenStream, proc_macro::TokenStream) -> proc_macro::TokenStream>
             at C:\Users\ethanhs\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\src\libproc_macro\bridge\client.rs:408
  39: <rustc_expand::mbe::TokenTree as core::fmt::Debug>::fmt
  40: <rustc_expand::proc_macro::AttrProcMacro as rustc_expand::base::AttrProcMacro>::expand
  41: rustc_expand::expand::MacroExpander::fully_expand_fragment
  42: rustc_expand::expand::MacroExpander::expand_crate
  43: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::compile
  44: rustc_interface::passes::BoxedResolver::to_resolver_outputs
  45: rustc_interface::passes::BoxedResolver::complete
  46: rustc_interface::passes::BoxedResolver::complete
  47: <rustc_interface::util::ReplaceBodyWithLoop as rustc_ast::mut_visit::MutVisitor>::visit_mac
  48: rustc_interface::queries::Queries::expansion
  49: rustc_driver::pretty::print_after_hir_lowering
  50: <rustc_typeck::collect::ItemCtxt as rustc_typeck::astconv::AstConv>::re_infer
  51: <rustc_typeck::collect::ItemCtxt as rustc_typeck::astconv::AstConv>::re_infer
  52: <rustc_ast_passes::node_count::NodeCounter as rustc_ast::visit::Visitor>::visit_attribute
  53: rustc_driver::pretty::print_after_hir_lowering
  54: ZN244_$LT$std..error..$LT$impl$u20$core..convert..From$LT$alloc..string..String$GT$$u20$for$u20$alloc..boxed..Box$LT$dyn$u20$std..error..Error$u2b$core..marker..Sync$u2b$core
..marker..Send$GT$$GT$..from..StringError$u20$as$u20$core..fmt..Display$GT$3fmt17
  55: std::sys::windows::thread::Thread::new
  56: BaseThreadInitThunk
  57: RtlUserThreadStart
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (dbf8b6bf1 2020-04-19) running on x86_64-pc-windows-msvc

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack
error: custom attribute panicked
 --> src\main.rs:2:1
  |
2 | #[hello]
  | ^^^^^^^^
  |
  = help: message: `"set_r#raw"` is not a valid identifier

error: aborting due to previous error

error: could not compile `proctest`.

To learn more, run the command again with --verbose.

[petrochenkov]

Duplicate of #59998.

[emmatyping]

Thanks, sorry for the dupe :)