Add proper name mangling for pattern types

[oli-obk]

requires adding demangler support first rust-lang/rustc-demangle#81

needed for #136006 (comment) as otherwise we will have symbol collisions

[rustbot]

r? @petrochenkov

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[rust-log-analyzer]

The job aarch64-gnu-llvm-19-1 failed! Check out the build log: (web) (plain)

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---- [codegen] tests/codegen/pattern_type_symbols.rs stdout ----

error: compilation failed!
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/codegen/pattern_type_symbols.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--check-cfg" "cfg(test,FALSE)" "-O" "-Cdebug-assertions=no" "--emit" "llvm-ir" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/codegen/pattern_type_symbols/pattern_type_symbols.ll" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Csymbol-mangling-version=v0" "-Copt-level=0" "--crate-type=lib"
stdout: none
--- stderr -------------------------------

thread 'rustc' panicked at compiler/rustc_symbol_mangling/src/lib.rs:317:5:
compute_symbol_name: `_RINvCs3QvG2ESzx2Q_20pattern_type_symbols3fooWmRm0_m3b9ac9ff_EB2_` cannot be demangled
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: rustc_symbol_mangling::symbol_name_provider
      [... omitted 3 frames ...]
   3: <rustc_middle::mir::mono::MonoItem>::symbol_name
   4: <core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>, rustc_monomorphize::partitioning::assert_symbols_are_distinct<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>>::{closure#0}> as core::iter::traits::iterator::Iterator>::fold::<(), core::iter::traits::iterator::Iterator::for_each::call<(&rustc_middle::mir::mono::MonoItem, rustc_middle::ty::SymbolName), <alloc::vec::Vec<(&rustc_middle::mir::mono::MonoItem, rustc_middle::ty::SymbolName)>>::extend_trusted<core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>, rustc_monomorphize::partitioning::assert_symbols_are_distinct<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>>::{closure#0}>>::{closure#0}>::{closure#0}>
   5: <alloc::vec::Vec<(&rustc_middle::mir::mono::MonoItem, rustc_middle::ty::SymbolName)> as alloc::vec::spec_from_iter::SpecFromIter<(&rustc_middle::mir::mono::MonoItem, rustc_middle::ty::SymbolName), core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>, rustc_monomorphize::partitioning::assert_symbols_are_distinct<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>>::{closure#0}>>>::from_iter
   6: rustc_monomorphize::partitioning::assert_symbols_are_distinct::<core::slice::iter::Iter<rustc_middle::mir::mono::MonoItem>>
   7: <rustc_session::session::Session>::time::<(&[rustc_middle::mir::mono::CodegenUnit], ()), rustc_monomorphize::partitioning::collect_and_partition_mono_items::{closure#0}>
   8: rustc_monomorphize::partitioning::collect_and_partition_mono_items
      [... omitted 3 frames ...]
   9: rustc_codegen_ssa::back::symbol_export::exported_symbols_provider_local
      [... omitted 3 frames ...]
  10: <rustc_metadata::rmeta::encoder::EncodeContext>::encode_crate_root
  11: rustc_metadata::rmeta::encoder::encode_metadata
  12: rustc_metadata::fs::encode_and_write_metadata
  13: rustc_interface::passes::start_codegen
  14: <rustc_interface::queries::Linker>::codegen_and_build_linker
  15: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>
  16: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}>
  17: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  18: <alloc::boxed::Box<dyn for<'a> core::ops::function::FnOnce<(&'a rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &'a std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena<'a>>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}), Output = core::option::Option<rustc_interface::queries::Linker>>> as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once
  19: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>
  20: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  21: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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

note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly

note: rustc 1.89.0-nightly (84e9b789c 2025-06-12) running on aarch64-unknown-linux-gnu

note: compiler flags: -Z threads=1 -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/cargo -Z ignore-directory-in-diagnostics-source-blocks=/checkout/vendor -C debug-assertions=no -C prefer-dynamic -C rpath -C debuginfo=0 -C symbol-mangling-version=v0 -C opt-level=0 --crate-type lib

query stack during panic:
#0 [symbol_name] computing the symbol for `foo::<(u32) is ValTree(Leaf(0x00000000): u32)..=ValTree(Leaf(0x3b9ac9ff): u32)>`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
#2 [exported_symbols] collecting exported symbols for crate `0`
end of query stack
------------------------------------------

[wesleywiser]

Can you update the v0 mangling docs to incorporate the new manglings?