fix #476: isdefined with QuoteNode

[simeonschaub]

No description provided.

[codecov]

Codecov Report

Merging #477 (63dd5b3) into master (5e723d4) will increase coverage by 0.00%.
The diff coverage is 66.66%.

@@           Coverage Diff           @@
##           master     #477   +/-   ##
=======================================
  Coverage   89.28%   89.29%           
=======================================
  Files          12       12           
  Lines        2342     2344    +2     
=======================================
+ Hits         2091     2093    +2     
  Misses        251      251           

Impacted Files	Coverage Δ
src/interpret.jl	86.87% <66.66%> (+0.06%)	⬆️

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[pfitzseb]

This seems correct to me, although I'm a bit uncomfortable with removing the error fallback (mostly because I'm too unfamiliar with what else is valid in a @isdefined expression).

[simeonschaub]

Ok, I just had a look at what the base interpreter does and looks like it is buggy as well 😆 (it will error if asserts are enabled):

~ >>> julia-latest --compile=min                                                                              ✓ 506
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.7.0-DEV.945 (2021-04-18)
 _/ |\__'_|_|_|\__'_|  |  Commit 55dd2f4e92* (4 days old master)
|__/                   |

julia> @generated f() = Expr(:isdefined, :($(QuoteNode(Float64))))
f (generic function with 1 method)

julia> f()
false

Base has an additional case for Core.Argument, which I don't really think should occur in untyped IR, but I can add this here as well.