LLVM assertion hit when bootstrapping with a local rustc ("Invoking a function with bad signature")

[lucab]

I'm currently trying to bootstrap current rust from a system-installed copy of itself, by doing firstly a normal installation and then the second one using --enable-local-rust. However the build fails on libstd, triggering a LLVM assertion in rustc. Both local-stage0 and source tree are at 548b8ce.

Build failure:

lucab@galatea:~/rust$ which rustc
/usr/local/bin/rustc
lucab@galatea:~/rust$ rustc -v
rustc 0.10-pre (548b8ce 2014-02-08 15:31:32 +0100)
host: x86_64-unknown-linux-gnu
lucab@galatea:~/rust$ ./configure --enable-local-rust --prefix=/usr
...
lucab@galatea:~/rust$ make VERBOSE=1
cfg: build triple x86_64-unknown-linux-gnu
cfg: host triples x86_64-unknown-linux-gnu
cfg: target triples x86_64-unknown-linux-gnu
cfg: enabling more debugging (CFG_ENABLE_DEBUG)
cfg: host for x86_64-unknown-linux-gnu is x86_64
cfg: os for x86_64-unknown-linux-gnu is unknown-linux-gnu
cfg: using gcc
cfg: no pandoc found, omitting docs
cfg: no node found, omitting docs
cfg: no llnextgen found, omitting grammar-verification
MATCHES=""; if [ -n "$MATCHES" ] ; then echo "warning: removing previous" \'libstd-*.so\' "libraries:" $MATCHES; rm $MATCHES ; fi
MATCHES=""; if [ -n "$MATCHES" ] ; then echo "warning: removing previous" \'libstd-*.rlib\' "libraries:" $MATCHES; rm $MATCHES ; fi
x86_64-unknown-linux-gnu/stage0/bin/rustc --cfg stage0  -O --cfg rtopt --cfg debug -Z prefer-dynamic --target=x86_64-unknown-linux-gnu  -W warnings -L "x86_64-unknown-linux-gnu/rt" -L "/home/lucab/rust/x86_64-unknown-linux-gnu/llvm/Release+Asserts/lib" --out-dir x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib /home/lucab/rust/src/libstd/lib.rs
rustc: /home/lucab/rust/src/llvm/lib/IR/Instructions.cpp:544: void llvm::InvokeInst::init(llvm::Value*, llvm::BasicBlock*, llvm::BasicBlock*, llvm::ArrayRef<llvm::Value*>, const llvm::Twine&): Assertion `((Args.size() == FTy->getNumParams()) || (FTy->isVarArg() && Args.size() > FTy->getNumParams())) && "Invoking a function with bad signature"' failed.
Aborted

Assertion backtrace:

Starting program: /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/rustc --cfg stage0 -O --cfg rtopt --cfg debug -Z prefer-dynamic --target=x86_64-unknown-linux-gnu -W warnings -L x86_64-unknown-linux-gnu/rt -L /home/lucab/rust/x86_64-unknown-linux-gnu/llvm/Release+Asserts/lib --out-dir x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib /home/lucab/rust/src/libstd/lib.rs
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff7f82700 (LWP 30705)]
[New Thread 0x7ffff0598700 (LWP 30706)]
[New Thread 0x7ffff0497700 (LWP 30707)]
[New Thread 0x7ffff0396700 (LWP 30708)]
[New Thread 0x7fffeacec700 (LWP 30709)]
[New Thread 0x7fffea4eb700 (LWP 30710)]
[New Thread 0x7fffe9cea700 (LWP 30711)]
[New Thread 0x7fffe94e9700 (LWP 30712)]

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7ffff7f82700 (LWP 30705)]
0x00007ffff1392475 in *__GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
64  ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
#0  0x00007ffff1392475 in *__GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
        pid = <optimized out>
        selftid = <optimized out>
#1  0x00007ffff13956f0 in *__GI_abort () at abort.c:92
        act = {__sigaction_handler = {sa_handler = 0x7ffff43902b0, sa_sigaction = 0x7ffff43902b0}, sa_mask = {__val = {140737241599019, 140737152774736, 544, 
              140737152774976, 140737240658758, 206158430232, 140737152774992, 140737152774768, 140737240557112, 206158430256, 140737152775016, 225349584, 
              225349568, 10, 7017206802398410528, 140737488349126}}, sa_flags = -246764431, sa_restorer = 0x7ffff438fdd8}
        sigs = {__val = {32, 0 <repeats 15 times>}}
#2  0x00007ffff138b621 in *__GI___assert_fail (
    assertion=0x7ffff43902b0 "((Args.size() == FTy->getNumParams()) || (FTy->isVarArg() && Args.size() > FTy->getNumParams())) && \"Invoking a function with bad signature\"", file=<optimized out>, line=544, 
    function=0x7ffff4398ea0 "void llvm::InvokeInst::init(llvm::Value*, llvm::BasicBlock*, llvm::BasicBlock*, llvm::ArrayRef<llvm::Value*>, const llvm::Twine&)")
    at assert.c:81
        buf = 0xd6e8fd0 "rustc: /home/lucab/rust/src/llvm/lib/IR/Instructions.cpp:544: void llvm::InvokeInst::init(llvm::Value*, llvm::BasicBlock*, llvm::BasicBlock*, llvm::ArrayRef<llvm::Value*>, const llvm::Twine&): Asserti"...
#3  0x00007ffff3a46b35 in llvm::InvokeInst::init (this=0xd6e8e00, Fn=0xd6db720, IfNormal=0xd6db860, IfException=0xd6db960, Args=..., NameStr=...)
    at /home/lucab/rust/src/llvm/lib/IR/Instructions.cpp:542
        __PRETTY_FUNCTION__ = "void llvm::InvokeInst::init(llvm::Value*, llvm::BasicBlock*, llvm::BasicBlock*, llvm::ArrayRef<llvm::Value*>, const llvm::Twine&)"
        FTy = 0x8487290
#4  0x00007ffff2bf3e15 in llvm::InvokeInst::InvokeInst (this=0xd6e8e00, Func=0xd6db720, IfNormal=0xd6db860, IfException=0xd6db960, Args=..., Values=6, 
    NameStr=..., InsertBefore=0x0) at /home/lucab/rust/src/llvm/include/llvm/IR/Instructions.h:3081
No locals.
#5  0x00007ffff2bf3c6d in llvm::InvokeInst::Create (Func=0xd6db720, IfNormal=0xd6db860, IfException=0xd6db960, Args=..., NameStr=..., InsertBefore=0x0)
    at /home/lucab/rust/src/llvm/include/llvm/IR/Instructions.h:2883
        Values = 6
#6  0x00007ffff2bfd7ad in llvm::IRBuilder<true, llvm::ConstantFolder, llvm::IRBuilderDefaultInserter<true> >::CreateInvoke (this=0x81e1430, Callee=0xd6db720, 
    NormalDest=0xd6db860, UnwindDest=0xd6db960, Args=..., Name=...) at /home/lucab/rust/src/llvm/include/llvm/IR/IRBuilder.h:579
No locals.
#7  0x00007ffff3998ff6 in LLVMBuildInvoke (B=0x81e1430, Fn=0xd6db720, Args=0xd6db5b0, NumArgs=3, Then=0xd6db860, Catch=0xd6db960, Name=0x7ffff3bcdc90 "")
    at /home/lucab/rust/src/llvm/lib/IR/Core.cpp:1976
No locals.
#8  0x00007ffff2087f64 in middle::trans::builder::Builder::invoke::h8b21487c25e1f39f6vaw::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#9  0x00007ffff208781e in middle::trans::build::Invoke::h33b75f77684e1c7caP::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#10 0x00007ffff1f75fd7 in middle::trans::base::invoke::h7b99a5d2ef6bce67aB::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#11 0x00007ffff1ff27b0 in middle::trans::callee::trans_call_inner::h65b762decf104040am::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#12 0x00007ffff1f65334 in middle::trans::callee::trans_lang_call::ha98dda63a8d04c9ca5::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#13 0x00007ffff202d0e0 in middle::trans::base::malloc_raw_dyn::h045498d24488489faN::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#14 0x00007ffff20a1993 in middle::trans::base::malloc_raw::h5a888fdf11d6a03aaT::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#15 0x00007ffff212008b in middle::trans::closure::allocate_cbox::hc22b01a365a948d1aB::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#16 0x00007ffff212051e in middle::trans::closure::store_environment::h80efec85b84d0169ad::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#17 0x00007ffff2121de9 in middle::trans::closure::build_closure::h92d3350bccfabdbfab::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#18 0x00007ffff20238a3 in middle::trans::closure::trans_expr_fn::he2ef742c7e1a5a71ad::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#19 0x00007ffff20027e1 in middle::trans::expr::trans_rvalue_dps_unadjusted::h71e2e1b92f9a2079aJ::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#20 0x00007ffff1f49df0 in middle::trans::expr::trans_into::h2bc8cbb134e2b361aA::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#21 0x00007ffff211a5fb in middle::trans::_match::store_local::anon::expr_fn::aF ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#22 0x00007ffff211a3ad in middle::trans::_match::mk_binding_alloca::h3196e78b09a11ce7aD::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#23 0x00007ffff20ad4a4 in middle::trans::_match::store_local::h536612f706bb496aaD::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#24 0x00007ffff1f4a1ef in middle::trans::base::init_local::hafbbd1d1a16c8c11al::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#25 0x00007ffff1f48aef in middle::trans::controlflow::trans_stmt::h9b036c36c2a4a8acaO::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#26 0x00007ffff1f4a8e7 in middle::trans::controlflow::trans_block::h6728809e1547fe5baP::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#27 0x00007ffff2000ff4 in middle::trans::expr::trans_rvalue_dps_unadjusted::h71e2e1b92f9a2079aJ::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#28 0x00007ffff1f49df0 in middle::trans::expr::trans_into::h2bc8cbb134e2b361aA::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#29 0x00007ffff211a5fb in middle::trans::_match::store_local::anon::expr_fn::aF ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#30 0x00007ffff211a3ad in middle::trans::_match::mk_binding_alloca::h3196e78b09a11ce7aD::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#31 0x00007ffff20ad4a4 in middle::trans::_match::store_local::h536612f706bb496aaD::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#32 0x00007ffff1f4a1ef in middle::trans::base::init_local::hafbbd1d1a16c8c11al::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#33 0x00007ffff1f48aef in middle::trans::controlflow::trans_stmt::h9b036c36c2a4a8acaO::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#34 0x00007ffff1f4a8e7 in middle::trans::controlflow::trans_block::h6728809e1547fe5baP::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#35 0x00007ffff20b6d0e in middle::trans::base::trans_closure::h1759f1814c6d2e76aP::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#36 0x00007ffff1ef869e in middle::trans::base::trans_fn::h6f0f174d360b610daK::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#37 0x00007ffff20bfb56 in middle::trans::meth::trans_impl::h730683530bb6e459ah::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#38 0x00007ffff1ef1b41 in middle::trans::base::trans_item::h4facb9b8ae69d25baJ::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#39 0x00007ffff20bfdd7 in middle::trans::base::trans_mod::h6e8f18b8ebac9ed9ak::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#40 0x00007ffff1ef12f0 in middle::trans::base::trans_item::h4facb9b8ae69d25baJ::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#41 0x00007ffff20bfdd7 in middle::trans::base::trans_mod::h6e8f18b8ebac9ed9ak::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#42 0x00007ffff20d683d in middle::trans::base::trans_crate::hfb08affed303adbfaH::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#43 0x00007ffff2b405b5 in driver::driver::phase_4_translate_to_llvm::anon::expr_fn::aW ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#44 0x00007ffff2b3fffd in util::common::time::h1fab99fadad0c8ffaQ::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#45 0x00007ffff2b3fe89 in driver::driver::phase_4_translate_to_llvm::h9d7a2f7f560a1fc8aj::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#46 0x00007ffff2b458a0 in driver::driver::compile_input::h9185223560d274d9a7::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#47 0x00007ffff2ba05e0 in run_compiler::h09797a414b183ccdaX::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#48 0x00007ffff2bb3425 in main_args::anon::expr_fn::aQ () from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#49 0x00007ffff2baf2e6 in monitor::anon::expr_fn::aF () from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#50 0x00007ffff2ba923d in task::TaskBuilder::try::anon::expr_fn::POaFab ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/librustc-0d83f02f-0.10-pre.so
No symbol table info available.
#51 0x00007ffff7305fe3 in task::__extensions__::build_start_wrapper::anon::anon::expr_fn::ap ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libgreen-80d9e76a-0.10-pre.so
No symbol table info available.
#52 0x00007ffff7639a2f in unstable::finally::Finally$$CLOSURE$::finally::ha36f8aa836360c9eQ2aO::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#53 0x00007ffff771accc in rt::task::__extensions__::run::anon::expr_fn::a5 ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#54 0x00007ffff772d338 in rt::unwind::Unwinder::try::try_fn::__rust_abi::mk ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#55 0x00007ffff772d202 in rt::unwind::Unwinder::try::try_fn::h9894487fcce78d78mkab::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#56 0x00007ffff77376ac in rust_try () from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#57 0x00007ffff771b680 in rt::unwind::Unwinder::try::hd640a244e2e9e8dbmkaj::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#58 0x00007ffff771ab96 in rt::task::Task::run::h4244ee88506b30cfUma2::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libstd-966edb7e-0.10-pre.so
No symbol table info available.
#59 0x00007ffff7305cbb in task::__extensions__::build_start_wrapper::anon::expr_fn::ah ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libgreen-80d9e76a-0.10-pre.so
No symbol table info available.
#60 0x00007ffff72e19c6 in context::Context::new::task_start_wrapper::__rust_abi::qv ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libgreen-80d9e76a-0.10-pre.so
No symbol table info available.
#61 0x00007ffff72e1963 in context::Context::new::task_start_wrapper::hd735b0bb41d8d6e5qvaz::v0.10.pre ()
   from /home/lucab/rust/x86_64-unknown-linux-gnu/stage0/bin/../lib/libgreen-80d9e76a-0.10-pre.so
No symbol table info available.
#62 0x0000000000000000 in ?? ()
No symbol table info available.

System is an amd64 debian wheezy (stable 7.1), using gcc-4.7 and rust embedded LLVM copy. Is there any way to get more debug info on rust side?

[huonw]

This is probably because the signatures of lang items have changed between the stage0 snapshot and the current commit and we don't type check them (#9307), so the local-rust compiler is generating calls to the stage0 functions which differ from the stage1/stage2 functions.

Running with RUST_LOG=rustc::middle::trans set will give some debugging output, but it'll probably be far too much.

[lucab]

I think that you may have got this right, and this could be related to different arity of closure_exchange_malloc between stages (2-ary in stage0, 3-ary elsewhere).

I managed to get some output from middle::trans. A lot, actually (~65MB), so I'm just pasting the last relevant lines of it here.

From what I can understand, this is getting stuck in the middle of std::task::TaskBuilder::addr_wrapper(), when trying to invoke a 2-ary std::rt::global_heap::closure_exchange_malloc() while passing it 3 arguments.
At that point, Args.size() is 3 while FTy->getNumParams() is 2 and assertion is hit.

[lucab]

So, this is happening due to the recently landed #12059. I'll wait for the next snapshot to happen and the legacy removed before trying again.

[alexcrichton]

Closing, this is just a relic of the local rust root not being the exact snapshot that we currently need.

We could verify that enable-local-rust has a specific SHA in the range that the snapshot compiler is in (ABI-wise), but at this point I don't think it's worth it that much.