0.4.8 lets a.[1] parse and lower

[LilithHafner]

This came up at JuliaLang/julia#53119

@LilithHafnerBot bisect()

using JuliaSyntax
JuliaSyntax.parse("a.[1]")

[savq]

Note that this was allowed in the flisp parser.

julia +lts -E ':(a.[1])'                                                                                                                                      
:(a.:([1]))

[LilithHafner]

There was a bug in the bisector backend. Should hopefully be fixed now.

@LilithHafnerBot bisect()

using JuliaSyntax
JuliaSyntax.parse(Expr, "a.[1]")

[LilithHafnerBot]

❌ Bisect failed

Commit	stdout
b1c6d54	a.:([1])
a6f2d15	a.:([1])

[LilithHafner]

@LilithHafnerBot bisect()

using JuliaSyntax
JuliaSyntax.enable_in_core!()
eval(Meta.parse("""
Meta.lower(Main, :(a.[1]))
"""))

[LilithHafnerBot]

✅ Bisect succeeded! The first new commit is 296cd5e

Commit	stdout
b1c6d54	$(Expr(:error, "invalid syntax "a.[1]""))
e3e447d	$(Expr(:error, "invalid syntax "a.[1]""))
8731bab	$(Expr(:error, "invalid syntax "a.[1]""))
6da0fc4	$(Expr(:error, "invalid syntax "a.[1]""))
5aad812	$(Expr(:error, "invalid syntax "a.[1]""))
296cd5e	$(Expr(:thunk, CodeInfo(⏎ @ none within top-level scope⏎1 ─ %1 = Base.getproperty(a, $(Quote...
df84e02	$(Expr(:thunk, CodeInfo(⏎ @ none within top-level scope⏎1 ─ %1 = Base.getproperty(a, $(Quote...
a6f2d15	$(Expr(:thunk, CodeInfo(⏎ @ none within top-level scope⏎1 ─ %1 = Base.getproperty(a, $(Quote...

[LilithHafner]

@LilithHafnerBot bisect()

using JuliaSyntax
dump(JuliaSyntax.parse(Expr, "a.[1]"))

[LilithHafnerBot]

✅ Bisect succeeded! The first new commit is 296cd5e

Commit	stdout
b1c6d54	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: Expr⏎ head: Symbol quo...
e3e447d	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: Expr⏎ head: Symbol quo...
8731bab	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: Expr⏎ head: Symbol quo...
6da0fc4	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: Expr⏎ head: Symbol quo...
5aad812	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: Expr⏎ head: Symbol quo...
296cd5e	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: QuoteNode⏎ value: Expr...
df84e02	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: QuoteNode⏎ value: Expr...
a6f2d15	Expr⏎ head: Symbol .⏎ args: Array{Any}((2,))⏎ 1: Symbol a⏎ 2: QuoteNode⏎ value: Expr...

[LilithHafner]

Alas, @savq, the old and new parsing results both print to :(a.:([1])), but they are not the same.

julia> old = Expr(:., :a, Expr(:quote, :([1])))
:(a.:([1]))

julia> new = Expr(:., :a, QuoteNode(:([1])))
:(a.:([1]))

julia> old == new
false

julia> Meta.lower(Main, old)
:($(Expr(:error, "invalid syntax \"a.[1]\"")))

julia> Meta.lower(Main, new)
:($(Expr(:thunk, CodeInfo(
    @ none within `top-level scope'
1 ─ %1 = Base.getproperty(a, $(QuoteNode(:([1]))))
└──      return %1
))))

From the commit message, this looks intentional; perhaps the appropriate fix is to prohibit this in lowering (and possibly gate the new parsing to new versions of Julia)

[pfitzseb]

Are Expr(:quote, ...) and QuoteNode(...) semantically identical?