QuoteNode, LineNumberNode leaking into macros

[TotalVerb]

julia> macro foo(ex)
           dump(ex)
       end
@foo (macro with 1 method)

julia> @foo :x
QuoteNode
  value: Symbol x

julia> @foo begin
           1
           2
       end
Expr
  head: Symbol block
  args: Array{Any}((4,))
    1: LineNumberNode
      line: Int64 2
      file: Symbol REPL[12]
    2: Int64 1
    3: LineNumberNode
      line: Int64 3
      file: Symbol REPL[12]
    4: Int64 2
  typ: Any

The behavior here is different than the previous behavior of passing these in as Expr(:quote) and Expr(:line). If this is an intended change (which would be unfortunate, in my opinion), then it should be documented in NEWS.

[TotalVerb]

Probably related to #23533, cc @vtjnash

[vtjnash]

essentially a dup of #15310

[kmsquire]

Except that, presumably, #15310 didn't cause breakage in DataStructures.jl?

[JeffBezanson]

I don't think it's a dup; that was about expressions returned from macros, while this is a change in what we pass to macros.

[JeffBezanson]

After exploring this, it seems we've been using QuoteNode and LineNumberNode quite a bit. Trying to eliminate them from macro arguments actually required more code changes, so we'll keep the new behavior. It's in the ast devdocs, but the summary is that QuoteNode is used for quoted atoms (e.g. symbols) and LineNumberNode is used for all line number info.