repr on expressions containing $ or a keyword as identifier is not re-evaluable

[lucaferranti]

The title wording is maybe a bit clumsy, but the following example should convey the meaning. calling repr on the expression adds an extra backslash, which leads to a different expression when parsed back.

julia> s = gensym(:$)
Symbol("##\$#1002508")

julia> ex = :($s = 1 + 1)
:(var"##\$#1002508" = 1 + 1)

julia> new_ex = eval(Meta.parse(repr(ex)))
:(var"##\\\$#1002508" = 1 + 1)

julia> ex == new_ex
false

[lucaferranti]

More generically, if my expression contains an identifier like var"some_keyword" or var"$" calling repr and parsing back leads to a different expression or error

julia> ex = :(var"$"())
:($())

julia> eval(Meta.parse(repr(ex)))
()

julia> ex = :(var"$$"())
:(var"\$\$"())

julia> eval(Meta.parse(repr(ex)))
:(var"\\\$\\\$"())

julia> ex = :(var"try"())
:(try())

julia> eval(Meta.parse(repr(ex)))
ERROR: ParseError:
# Error @ none:1:3
:(try())
# └───┘ ── try without catch or finally
Stacktrace:
 [1] #parse#3
   @ ./meta.jl:244 [inlined]
 [2] parse
   @ ./meta.jl:236 [inlined]
 [3] parse(str::String; filename::String, raise::Bool, depwarn::Bool)
   @ Base.Meta ./meta.jl:278
 [4] parse(str::String)
   @ Base.Meta ./meta.jl:276
 [5] top-level scope
   @ REPL[124]:1
 [6] top-level scope
   @ none:1