ICE with adt_const_params and instrument-coverage

[mikialex]

Run the following code with rustc -Cinstrument-coverage ./test.rs cause ICE.

Code

#![feature(adt_const_params)]
#![allow(incomplete_features)]

fn eval<const N: f32>() -> f32 {
  N
}

fn main() {
  println!("{}", eval::<0.5>());
}

Meta

rustc --version --verbose:

rustc 1.63.0-nightly (e09449220 2022-05-31)
binary: rustc
commit-hash: e0944922007e1bb4fe59809293acf4364410cccc
commit-date: 2022-05-31
host: x86_64-pc-windows-msvc
release: 1.63.0-nightly
LLVM version: 14.0.4

Error output

error: internal compiler error: compiler\rustc_symbol_mangling\src\v0.rs:728:17: symbol_names: unsupported constant of type `f32` (Const { ty: f32, val: Value(Scalar(0x3f000000)) 
})

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/e0944922007e1bb4fe59809293acf4364410cccc\compiler\rustc_errors\src\lib.rs:1335:9
stack backtrace:
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.63.0-nightly (e09449220 2022-05-31) running on x86_64-pc-windows-msvc

note: compiler flags: -C instrument-coverage

query stack during panic:
#0 [symbol_name] computing the symbol for `eval::<0.5f32>`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to previous error

Backtrace

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/e0944922007e1bb4fe59809293acf4364410cccc\compiler\rustc_errors\src\lib.rs:1335:9
stack backtrace:
   0:     0x7ffc1e6d9baf - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h29008f0d8360991f
   1:     0x7ffc1e714baa - core::fmt::write::h8a73e3be4bf01465
   2:     0x7ffc1e6cbfa9 - <std::io::IoSlice as core::fmt::Debug>::fmt::h5b68e796365090b2
   3:     0x7ffc1e6dd49b - std::panicking::default_hook::h9a42856a3bf2d779
   4:     0x7ffc1e6dd11b - std::panicking::default_hook::h9a42856a3bf2d779
   5:     0x7ffbf6a9dd96 - <rustc_metadata[f47eeeeabaa7db06]::rmeta::encoder::EncodeContext as rustc_serialize[ec78526cf068bb80]::serialize::Encoder>::emit_raw_bytes
   6:     0x7ffc1e6ddc42 - std::panicking::rust_panic_with_hook::h7fa68a9e3338055f
   7:     0x7ffbfaf50d25 - <rustc_middle[608b18733af6f849]::ty::closure::BorrowKind as core[1b81ed6b3b69d0c3]::fmt::Debug>::fmt
   8:     0x7ffbfaf4fb89 - <rustc_middle[608b18733af6f849]::ty::closure::BorrowKind as core[1b81ed6b3b69d0c3]::fmt::Debug>::fmt
   9:     0x7ffbfb5665c9 - rustc_middle[608b18733af6f849]::util::bug::bug_fmt
  10:     0x7ffbfb05b9d9 - <rustc_middle[608b18733af6f849]::ty::sty::TypeAndMut as rustc_middle[608b18733af6f849]::ty::context::Lift>::lift_to_tcx
  11:     0x7ffbfb042383 - <rustc_middle[608b18733af6f849]::ty::sty::TypeAndMut as rustc_middle[608b18733af6f849]::ty::context::Lift>::lift_to_tcx
  12:     0x7ffbfb0400b2 - <rustc_middle[608b18733af6f849]::ty::sty::TypeAndMut as rustc_middle[608b18733af6f849]::ty::context::Lift>::lift_to_tcx
  13:     0x7ffbfb0167a9 - <rustc_middle[608b18733af6f849]::ty::consts::valtree::ValTree>::zst
  14:     0x7ffbfb01682c - <rustc_middle[608b18733af6f849]::ty::consts::valtree::ValTree>::zst
  15:     0x7ffbfb565ae8 - rustc_middle[608b18733af6f849]::util::bug::bug_fmt
  16:     0x7ffbfa4dd74d - <&mut rustc_symbol_mangling[7008d1b4a8560b2c]::v0::SymbolMangler as rustc_middle[608b18733af6f849]::ty::print::Printer>::print_const
  17:     0x7ffbfa4de006 - <&mut rustc_symbol_mangling[7008d1b4a8560b2c]::v0::SymbolMangler as rustc_middle[608b18733af6f849]::ty::print::Printer>::path_qualified
  18:     0x7ffbfa4d8c31 - <&mut rustc_symbol_mangling[7008d1b4a8560b2c]::v0::SymbolMangler as rustc_middle[608b18733af6f849]::ty::print::Printer>::print_def_path
  19:     0x7ffbfa4d6fa9 - rustc_symbol_mangling[7008d1b4a8560b2c]::typeid_for_fnabi
  20:     0x7ffbfa4d5d3d - rustc_symbol_mangling[7008d1b4a8560b2c]::provide
  21:     0x7ffbfa2ade22 - <&[rustc_middle[608b18733af6f849]::thir::abstract_const::Node] as rustc_serialize[ec78526cf068bb80]::serialize::Decodable<rustc_query_impl[300e2971295ed741]::on_disk_cache::CacheDecoder>>::decode
  22:     0x7ffbf9f5d375 - <rustc_query_impl[300e2971295ed741]::Queries as rustc_middle[608b18733af6f849]::ty::query::QueryEngine>::try_mark_green
  23:     0x7ffbfb020c4e - <rustc_middle[608b18733af6f849]::mir::mono::MonoItem>::symbol_name
  24:     0x7ffbf8ff606e - <rustc_monomorphize[b3a1078a39399015]::partitioning::MonoItemPlacement as core[1b81ed6b3b69d0c3]::fmt::Debug>::fmt
  25:     0x7ffbf8fe606f - <rustc_monomorphize[b3a1078a39399015]::collector::MirNeighborCollector as rustc_middle[608b18733af6f849]::mir::visit::Visitor>::visit_operand
  26:     0x7ffbf8fcd54b - <tracing_subscriber[86062e48cce79c6b]::util::TryInitError as core[1b81ed6b3b69d0c3]::fmt::Debug>::fmt
  27:     0x7ffbf8fed13c - <rustc_monomorphize[b3a1078a39399015]::partitioning::MonoItemPlacement as core[1b81ed6b3b69d0c3]::fmt::Debug>::fmt
  28:     0x7ffbf8fe65c0 - <rustc_monomorphize[b3a1078a39399015]::collector::MirNeighborCollector as rustc_middle[608b18733af6f849]::mir::visit::Visitor>::visit_operand
  29:     0x7ffbfa24e489 - <&[rustc_middle[608b18733af6f849]::thir::abstract_const::Node] as rustc_serialize[ec78526cf068bb80]::serialize::Decodable<rustc_query_impl[300e2971295ed741]::on_disk_cache::CacheDecoder>>::decode
  30:     0x7ffbfa2f3427 - <&[rustc_middle[608b18733af6f849]::thir::abstract_const::Node] as rustc_serialize[ec78526cf068bb80]::serialize::Decodable<rustc_query_impl[300e2971295ed741]::on_disk_cache::CacheDecoder>>::decode
  31:     0x7ffbf9f5dfd1 - <rustc_query_impl[300e2971295ed741]::Queries as rustc_middle[608b18733af6f849]::ty::query::QueryEngine>::try_mark_green
  32:     0x7ffbf6cbcff5 - <rustc_codegen_llvm[dab98a06ece5d8b2]::back::lto::ThinData as core[1b81ed6b3b69d0c3]::ops::drop::Drop>::drop
  33:     0x7ffbf6c582c5 - <rustc_codegen_llvm[dab98a06ece5d8b2]::LlvmCodegenBackend as rustc_codegen_ssa[cc51a84129a2d87c]::traits::backend::CodegenBackend>::codegen_crate       
  34:     0x7ffbf6b9a272 - <rustc_interface[713bcfa795747777]::queries::Linker>::link
  35:     0x7ffbf6b9497e - <rustc_interface[713bcfa795747777]::queries::Queries>::ongoing_codegen
  36:     0x7ffbf6a34ee4 - <&mut core[1b81ed6b3b69d0c3]::fmt::Formatter as serde[9162d223e4f5d80a]::ser::Serializer>::serialize_struct_variant
  37:     0x7ffbf6ab0ca5 - rustc_driver[5ae0ad532d132115]::pretty::print_after_hir_lowering
  38:     0x7ffbf6a549a0 - <&mut core[1b81ed6b3b69d0c3]::fmt::Formatter as serde[9162d223e4f5d80a]::ser::Serializer>::serialize_struct_variant
  39:     0x7ffbf6a2dd27 - <&mut core[1b81ed6b3b69d0c3]::fmt::Formatter as serde[9162d223e4f5d80a]::ser::Serializer>::serialize_struct_variant
  40:     0x7ffbf6a9aae6 - <rustc_metadata[f47eeeeabaa7db06]::rmeta::encoder::EncodeContext as rustc_serialize[ec78526cf068bb80]::serialize::Encoder>::emit_raw_bytes
  41:     0x7ffbf6a5d778 - <rustc_driver[5ae0ad532d132115]::args::Error as core[1b81ed6b3b69d0c3]::fmt::Debug>::fmt
  42:     0x7ffc1e6eedec - std::sys::windows::thread::Thread::new::h87bd3fa2cc7c7644
  43:     0x7ffc96367034 - BaseThreadInitThunk
  44:     0x7ffc97ba2651 - RtlUserThreadStart

[b-naber]

@rustbot claim

[wesleywiser]

I think this is only tangentially related to -Cinstrument-coverage in that using that flag enables -Csymbol-mangling-version=v0. The v0 mangling system doesn't currently implement support for floating point constants:

rust/compiler/rustc_symbol_mangling/src/v0.rs

Line 728 in 72f7e31

bug!("symbol_names: unsupported constant of type `{}` ({:?})", ct.ty(), ct);

The v0 mangling RFC describes how to define the floating point types:

https://github.com/rust-lang/rfcs/blob/9925276189646646beffbc4f84ca03b037ff7569/text/2603-rust-symbol-name-mangling-v0.md?plain=1#L695-L715

but does not define how to encode their values:

https://github.com/rust-lang/rfcs/blob/9925276189646646beffbc4f84ca03b037ff7569/text/2603-rust-symbol-name-mangling-v0.md?plain=1#L780-L783

So I think this will require design work and an amendment to that RFC to specify.

[tmiasko]

Floating point types are forbidden as const generic parameters. Since #98907 the appropriate error is emitted in this case.