Internal BoundsError: encountered unexpected error in runtime (1.5.3 and 1.6.0-beta1)

[yurivish]

This issue can be reproduced with a single line:

julia> (() -> ===(IOBuffer))()
Internal error: encountered unexpected error in runtime:
BoundsError(a=Array{Any, (2,)}[
  Main.:(===),
  Main.IOBuffer], i=(3,))
jl_bounds_error_ints at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
getindex at ./array.jl:801 [inlined]
getfield_elim_pass! at ./compiler/ssair/passes.jl:576
run_passes at ./compiler/ssair/driver.jl:132
optimize at ./compiler/optimize.jl:277 [inlined]
_typeinf at ./compiler/typeinfer.jl:239
typeinf at ./compiler/typeinfer.jl:211
typeinf_ext at ./compiler/typeinfer.jl:835
typeinf_ext_toplevel at ./compiler/typeinfer.jl:868
typeinf_ext_toplevel at ./compiler/typeinfer.jl:864
jfptr_typeinf_ext_toplevel_10828.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_type_infer at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_generate_fptr at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_compile_method_internal at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
do_call at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
eval_body at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_interpret_toplevel_thunk at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
top-level scope at REPL[1]:1
jl_toplevel_eval_flex at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_toplevel_eval_flex at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_toplevel_eval_in at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
eval at ./boot.jl:360
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
eval_user_input at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:139
repl_backend_loop at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:200
start_repl_backend at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:185
#run_repl#42 at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:317
run_repl at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:305
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#875 at ./client.jl:387
jfptr_YY.875_35832.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
do_apply at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_f__apply_latest at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#invokelatest#2 at ./essentials.jl:707 [inlined]
invokelatest at ./essentials.jl:706 [inlined]
run_main_repl at ./client.jl:372
exec_options at ./client.jl:302
_start at ./client.jl:485
jfptr__start_29117.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
true_main at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
repl_entrypoint at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
ERROR: ArgumentError: ===: too few arguments (expected 2)
Stacktrace:
 [1] (::var"#1#2")()
   @ Main ./REPL[1]:1
 [2] top-level scope
   @ REPL[1]:1

I saw other issues with the same symptom but they seem to have mostly been closed as fixed and it wasn't obvious to me that this issue is the same as any other open issue.

julia> versioninfo()
Julia Version 1.6.0-beta1
Commit b84990e1ac (2021-01-08 12:42 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin19.6.0)
  CPU: Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.0 (ORCJIT, skylake)

[JeffBezanson]

Duplicate of #40804; fixed.