Formatter: try to format macros that don't interpolate content

[asterite]

Fixes #12164

[HertzDevil]

Here any \{{ or \{% MacroLiterals from source will be unescaped. Is there a situation where a macro's body is valid Crystal code if it has the escaped forms, but becomes invalid when they are unescaped? (This should only affect a very small number of macros though.)

[asterite]

It seems that this might be already handled. I tried formatting this:

macro foo
  puts(\{{@type}}         )
end

And it actually produced this:

macro foo
  puts(\{{@type}})
end

There's a write_macro_slashes method. I didn't take a look at how it works (I might have written that but now I can't remember.)

I'd say, let's first find a case where it fails.

[HertzDevil]

On further thought, this is probably fine because it just means the macro contents are invalid after any interpolation. This is what I got:

{\{{ 1 }}}   # a TupleLiteral wrapping an escaped MacroLiteral
# becomes:
{{{ 1 }}}    # a MacroExpression wrapping a TupleLiteral

{ \{{ 1 }} } # a TupleLiteral wrapping an escaped MacroLiteral
# becomes:
{ {{ 1 }} }  # a TupleLiteral wrapping a MacroExpression

{\{{ 1 }} }  # a TupleLiteral wrapping an escaped MacroLiteral
# becomes:
{{{ 1 }} }   # invalid code

[asterite]

Hm, I'm not understanding. Is there something to fix? Based on the comment above, it looks so but I'm not sure 😅

Even if the macro contents are invalid, I don't think we should format those to something else.

[HertzDevil]

I think we can leave this check as is.

[zw963]

Thanks for fix this issue, it works!