[Pitch #2] Expression macros

[Douglas_Gregor]

@Jon_Shier

Is there any way to debug or get print output from the macro implementation right now? I'd like to explore what we get in there but these are libraries, not executables.

There's a debug dump. Pass -Xfrontend -dump-macro-expansions to the compiler and it'll emit something like this:

Macro expansion of #stringify(_:) in /path/to/MacroExamples/MacroExamples/main.swift:6:7-6:24 as (Int, String)
------------------------------
(x + y, "x + y")
------------------------------

Doug