ICE with new asm! macro and incremental compilation

[macpp]

Discovered when playing with new asm! macro #69171

How to reproduce

1. cargo run with following code:

fn main() {
    unsafe {
        asm!("nop")
    }
}

2. change asm! usage to

asm!("nop",out("invalid_reg")_)

building will result in error, because this is invalid register name ( this is 100% correct)

3. change back to asm!("nop") (same code as in 1)
   build will result with ICE:

thread 'rustc' panicked at 'missing specialization: `<rustc_middle::ty::query::on_disk_cache::CacheDecoder as SpecializedDecoder<&[rustc_ast::ast::InlineAsmTemplatePiece]>>::specialized_decode` not overridden', /rustc/3a7dfda40a3e798bf086bd58cc7e5e09deb808b5/src/libstd/macros.rs:16:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.tiyicn.workers.dev-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.tiyicn.workers.dev-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1537
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:490
  12: rust_begin_unwind
             at src/libstd/panicking.rs:388
  13: std::panicking::begin_panic_fmt
             at src/libstd/panicking.rs:342
  14: <E as serialize::serialize::SpecializationError>::not_found
  15: <rustc_middle::mir::Terminator as serialize::serialize::Decodable>::decode
  16: serialize::serialize::Decoder::read_option
  17: <rustc_middle::mir::BasicBlockData as serialize::serialize::Decodable>::decode
  18: serialize::serialize::Decoder::read_seq
  19: <rustc_middle::mir::Body as serialize::serialize::Decodable>::decode
  20: rustc_middle::ty::query::on_disk_cache::OnDiskCache::try_load_query_result
  21: rustc_middle::query::<impl rustc_query_system::query::config::QueryDescription<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::optimized_mir>::try_load_from_disk
  22: rustc_query_system::query::plumbing::load_from_disk_and_cache_in_memory
  23: rustc_data_structures::stack::ensure_sufficient_stack
  24: rustc_query_system::query::plumbing::get_query_impl
  25: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::instance_mir
  26: rustc_mir::monomorphize::collector::collect_neighbours
  27: rustc_data_structures::stack::ensure_sufficient_stack
  28: rustc_mir::monomorphize::collector::collect_items_rec
  29: rustc_session::utils::<impl rustc_session::session::Session>::time
  30: rustc_mir::monomorphize::collector::collect_crate_mono_items
  31: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  32: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::collect_and_partition_mono_items>::compute
  33: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  34: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  35: rustc_data_structures::stack::ensure_sufficient_stack
  36: rustc_query_system::query::plumbing::get_query_impl
  37: rustc_codegen_ssa::base::codegen_crate
  38: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  39: rustc_session::utils::<impl rustc_session::session::Session>::time
  40: rustc_interface::passes::start_codegen
  41: rustc_middle::ty::context::tls::enter_global
  42: rustc_interface::queries::Queries::ongoing_codegen
  43: rustc_interface::interface::run_compiler_in_existing_thread_pool
  44: scoped_tls::ScopedKey<T>::set
  45: rustc_ast::attr::with_globals
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 1.45.0-nightly (3a7dfda40 2020-05-19) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
#0 [optimized_mir] processing `main`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: could not compile `test_asm`.

Workarounds

• disable incremental compilation
• cargo clean

Meta

rustc --version --verbose:

rustc 1.45.0-nightly (3a7dfda40 2020-05-19)
binary: rustc
commit-hash: 3a7dfda40a3e798bf086bd58cc7e5e09deb808b5
commit-date: 2020-05-19
host: x86_64-unknown-linux-gnu
release: 1.45.0-nightly
LLVM version: 9.0

also fails on x86_64-pc-windows-gnu

[macpp]

cc @Amanieu

[Aaron1011]

@Amanieu: It looks like you're missing the decode modifier here:

rust/src/librustc_hir/arena.rs

Lines 17 to 18 in 8858a43

	[] asm_operand: rustc_hir::InlineAsmOperand<$tcx>,
	[] asm_template: rustc_ast::ast::InlineAsmTemplatePiece,

[Amanieu]

That doesn't seem to work since InlineAsmTemplatePiece isn't Copy.

[Aaron1011]

@Amanieu: It looks like it's nececessary to declare [] asm_operand: rustc_hir::InlineAsmOperand<$tcx> in both librustc_hir/arena.rs and librustc_middle/arena.rs. The error is caused by the wrong ArenaAllocatable trait being used (there are two - one for each crate that calls declare_arena.

Do you want to use your apporach, or should I open a PR with the arena changes?