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Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_builtin_macros/src/type_ascribe.rs | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/compiler/rustc_builtin_macros/src/type_ascribe.rs b/compiler/rustc_builtin_macros/src/type_ascribe.rs new file mode 100644 index 000000000..72b85af14 --- /dev/null +++ b/compiler/rustc_builtin_macros/src/type_ascribe.rs @@ -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)) +} |