String interpolation unaware of macro-local variables

[jacg]

This simple macro

macro foo ()
    quote
        a = 1
        println("a = ", a)
        println("a = $a")
    end
end

when expanded

println(macroexpand(:(@foo)))

gives

quote   #  line 3:
    #2 = 1  #  line 4:
    println("a = ", #2) #  line 5:
    println($(Base).sprint($(print), "a = ", a))
end

Consequently

@foo

gives

a = 1
a not defined

[JeffBezanson]

Oh how I hate string interpolation.

[StefanKarpinski]

Worst incredibly useful feature ever ;-)

[JeffBezanson]

Only fix I can really think of is to expand @str before the renaming pass as a special case.

[JeffBezanson]

By the way, imagine what it would be like to use string interpolation with gensyms. It would be so awkward that this issue wouldn't have even arisen :) It would be better to expand string interpolations at parse time maybe. Better still to get rid of them.

[StefanKarpinski]

I would be willing to expand @str before the renaming pass. Another option would be to make interpolation into normal strings more baked into the language and thereby possibly address #455, which probably shouldn't really be closed since it's resolution depends on triple-quotes, which we don't yet have.