1
Fork 0

Add unstable type_ascribe macro

This macro serves as a placeholder for future type ascription syntax to
make sure that the semantic implementation keeps working.
This commit is contained in:
Nilstrieb 2022-11-19 21:27:57 +01:00
parent 2a434286a9
commit 6ee0dd97e3
No known key found for this signature in database
6 changed files with 76 additions and 0 deletions

View file

@ -45,6 +45,7 @@ mod log_syntax;
mod source_util;
mod test;
mod trace_macros;
mod type_ascribe;
mod util;
pub mod asm;
@ -92,6 +93,7 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
unreachable: edition_panic::expand_unreachable,
stringify: source_util::expand_stringify,
trace_macros: trace_macros::expand_trace_macros,
type_ascribe: type_ascribe::expand_type_ascribe,
}
register_attr! {

View file

@ -0,0 +1,35 @@
use rustc_ast::ptr::P;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::{token, Expr, ExprKind, Ty};
use rustc_errors::PResult;
use rustc_expand::base::{self, DummyResult, ExtCtxt, MacEager};
use rustc_span::Span;
pub fn expand_type_ascribe(
cx: &mut ExtCtxt<'_>,
span: Span,
tts: TokenStream,
) -> Box<dyn base::MacResult + 'static> {
let (expr, ty) = match parse_ascribe(cx, tts) {
Ok(parsed) => parsed,
Err(mut err) => {
err.emit();
return DummyResult::any(span);
}
};
let asc_expr = cx.expr(span, ExprKind::Type(expr, ty));
return MacEager::expr(asc_expr);
}
fn parse_ascribe<'a>(cx: &mut ExtCtxt<'a>, stream: TokenStream) -> PResult<'a, (P<Expr>, P<Ty>)> {
let mut parser = cx.new_parser_from_tts(stream);
let expr = parser.parse_expr()?;
parser.expect(&token::Comma)?;
let ty = parser.parse_ty()?;
Ok((expr, ty))
}