JuliaSyntax misparses @var"\""

[Keno]

1.9 and JULIA_USE_FLISP_PARSER=1:

julia> macro var"\""(args...)
       1
       end
@" (macro with 1 method)

julia> @var"\""
1

master:

julia> macro var"\""(args...)
       1
       end
@" (macro with 1 method)

julia> @var"\""
ERROR: LoadError: UndefVarError: `@\"` not defined in `Main`
Suggestion: check for spelling errors or missing imports.
Stacktrace:
 [1] fl_lower
   @ ./flfrontend.jl:24 [inlined]
 [2] fl_lower(ex::Expr, mod::Module, filename::Ptr{UInt8}, lineno::UInt64)
   @ Base ./flfrontend.jl:23
in expression starting at REPL[2]:1

Found by inspecting JuliaSyntax source code rather than encountering it in any real code.

[Keno]

(Obviously applies to any var"" with raw string escape sequences)

[Keno]

Potential fix in JuliaLang/JuliaSyntax.jl#572, though if we think this is important, there's a 1-line change we could do in 1.12 to also fix it without the whole refactor.