I should be clearer about terminology. We have in the past used “compiler plugin” (and “syntax extension”) to refer to procedural macros. Macros (whether macros-by-example, currently using macro_rules!) or procedural are purely syntactic, they only interact with the parser, not the rest of the compiler. Type information is not available until much later in the compiler, by which time all macros have been expanded and have disappeared. So, a compiler plugin (in my sense of the concept) with access to type information is a very different beast from a macro (even a procedural macro) which only has access to the syntax.
I’d like for whitespace, comments and newline tokens (and other things hidden) to be in the token trees passed to procedural macros. The lexer will produce these tokens and they are trivial to ignore. Trying to recover this after is a lot more (ugly) work and I’m not sure if it possible in all cases (macros in macros aren’t too easy to reason about).
I have written some code to see if there’s whitespace to the left or right in tokens: https://github.com/AveryOS/avery/blob/daae05f04b24b1224b7381c9a416041c3186d1fd/vendor/asm/assembly.rs#L249
It is not pretty and I’d rather not see this duplicated in any procedural macros.
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