Unexpected error in runtime when squaring static diagonal matrices

[mschauer]

Possibly caused by a bug in StaticArrays but it looks to me something deeper goes wrong.

   _       _ _(_)_     |  Documentation: https://docs.julialang.org
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   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.1.0-DEV.276 (2018-09-17)
 _/ |\__'_|_|_|\__'_|  |  Commit 1324ceb81b* (11 days old master)
|__/                   |

julia> using StaticArrays

julia> x = @SVector rand(2)
2-element SArray{Tuple{2},Float64,1,2}:
 0.6358630318698844 
 0.27836149277496847

julia> Diagonal(x)^2
ERROR: UndefVarError: Diagonal not defined
Stacktrace:
 [1] top-level scope at none:0

julia> using LinearAlgebra

julia> Diagonal(x)^2
Internal error: encountered unexpected error in runtime:
MethodError(f=typeof(Base.string)(), args=(Expr(:call, :<, Expr(:., :ssa, :(:id)), Expr(:., :compact, :(:result_idx))),), world=0x0000000000000e7c)
rec_backtrace at /Users/schauermr/julia/src/stackwalk.c:94
record_backtrace at /Users/schauermr/julia/src/task.c:249 [inlined]
jl_throw at /Users/schauermr/julia/src/task.c:580
jl_method_error_bare at /Users/schauermr/julia/src/gf.c:1628
jl_method_error at /Users/schauermr/julia/src/gf.c:1646
jl_lookup_generic_ at /Users/schauermr/julia/src/gf.c:2174
jl_apply_generic at /Users/schauermr/julia/src/gf.c:2194
getindex at ./compiler/ssair/ir.jl:555
simple_walk at ./compiler/ssair/passes.jl:127
simple_walk_constraint at ./compiler/ssair/passes.jl:157
getfield_elim_pass! at ./compiler/ssair/passes.jl:641
run_passes at ./compiler/ssair/driver.jl:123
optimize at ./compiler/optimize.jl:162
typeinf at ./compiler/typeinfer.jl:35
typeinf_edge at ./compiler/typeinfer.jl:492
abstract_call_method at ./compiler/abstractinterpretation.jl:342
abstract_call_gf_by_type at ./compiler/abstractinterpretation.jl:81
abstract_call at ./compiler/abstractinterpretation.jl:790
abstract_eval_call at ./compiler/abstractinterpretation.jl:819
abstract_eval at ./compiler/abstractinterpretation.jl:904
typeinf_local at ./compiler/abstractinterpretation.jl:1147
typeinf_nocycle at ./compiler/abstractinterpretation.jl:1203
typeinf at ./compiler/typeinfer.jl:15
typeinf_edge at ./compiler/typeinfer.jl:492
abstract_call_method at ./compiler/abstractinterpretation.jl:342
abstract_call_gf_by_type at ./compiler/abstractinterpretation.jl:81
abstract_call at ./compiler/abstractinterpretation.jl:790
abstract_eval_call at ./compiler/abstractinterpretation.jl:819
abstract_eval at ./compiler/abstractinterpretation.jl:904
typeinf_local at ./compiler/abstractinterpretation.jl:1147
typeinf_nocycle at ./compiler/abstractinterpretation.jl:1203
typeinf at ./compiler/typeinfer.jl:15
typeinf_ext at ./compiler/typeinfer.jl:567
typeinf_ext at ./compiler/typeinfer.jl:604
jfptr_typeinf_ext_1 at /Users/schauermr/julia/usr/lib/julia/sys.dylib (unknown line)
jl_apply at /Users/schauermr/julia/src/./julia.h:1559 [inlined]
jl_apply_with_saved_exception_state at /Users/schauermr/julia/src/rtutils.c:252
jl_type_infer at /Users/schauermr/julia/src/gf.c:275
jl_compile_method_internal at /Users/schauermr/julia/src/gf.c:1798
jl_fptr_trampoline at /Users/schauermr/julia/src/gf.c:1842
do_call at /Users/schauermr/julia/src/interpreter.c:324
eval_stmt_value at /Users/schauermr/julia/src/interpreter.c:363 [inlined]
eval_body at /Users/schauermr/julia/src/interpreter.c:697
jl_interpret_toplevel_thunk_callback at /Users/schauermr/julia/src/interpreter.c:797
unknown function (ip: 0xfffffffffffffffe)
unknown function (ip: 0x1196f85af)
unknown function (ip: 0x2)
jl_interpret_toplevel_thunk at /Users/schauermr/julia/src/interpreter.c:806
jl_toplevel_eval_flex at /Users/schauermr/julia/src/toplevel.c:818
jl_toplevel_eval_in at /Users/schauermr/julia/src/builtins.c:622
eval at ./boot.jl:319
eval_user_input at /Users/schauermr/julia/usr/share/julia/stdlib/v1.1/REPL/src/REPL.jl:85
macro expansion at /Users/schauermr/julia/usr/share/julia/stdlib/v1.1/REPL/src/REPL.jl:117 [inlined]
#28 at ./task.jl:259
jl_apply at /Users/schauermr/julia/src/./julia.h:1559 [inlined]
start_task at /Users/schauermr/julia/src/task.c:271
2×2 Diagonal{Float64,SArray{Tuple{2},Float64,1,2}}:
 0.404322   ⋅       
  ⋅        0.0774851

[dpsanders]

Works fine for me with 1.1.0-DEV.308 (5 days old)

[mschauer]

Works on master for me as well. -11 days to -5 days is a short interval, is there something which might have fixed this or does it take a different code path by chance?

[mschauer]

Bisected to #29265 so perhaps not fixed yet

[mschauer]

Additional ref to #29107 which keeps track of perhaps related bugs

[mschauer]

Fixed by #29140